Obesity and Psychological Distress in Young Adults

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Co-supervision thesis

For the degree of Doctor

Université Libre de Buxelles

School of Public Health

And

Lebanese University

Doctoral School of Sciences and Technology

Speciality: Public Health, Epidemiology

Presented by

ABOU ABBAS Linda

Obesity and Psychological Distress in Young Adults

Thesis Director (Belgium) : Prof. GODIN Isabelle Thesis Director (Lebanon): Prof. SALAMEH Pascale

Defensed on December 22, 2015

Jury Members

Mr. Donnen Philippe, Professor - Université Libre de Bruxelles President

Mrs. Godin Isabelle, Professor - Université Libre de Bruxelles Director

Mrs. Salameh Pascale, Professor - Lebanese University Director

Mr. Dimassi Hani, Associate Professor - Lebanese American University Reviewer

Mrs. Robert Annie, Professor- Université Catholique de Louvain Reviewer

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LIST OF FIGURES

Figure 5.1.1 Flow chart of study selection strategy ... 39

Figure 5.1.2 Forest plot illustrating the results of a random-effects meta-analysis of the epidemiological studies investigating the association between obesity and depression among adult populations in selected countries of the Middle East. ... 42

Figure 5.1.3 Funnel plot for studies investigating the association between obesity and depression. ... 44

Figure 5.2.1 Histogram of BDS-22 ... 45

Figure 5.3.1 Scatterplot Graph between BDS-22 and BSQ-16 by gender ... 53

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LIST OF TABLES

Table 5.1.1 Characteristics and main findings of studies included in the meta-analysis... 40 Table 5.1.2 Quality assessment of included studies (Newcastle- Ottawa scale) ... 41 Table 5.1.3 Results of overall and subgroups analysis for the association between obesity and depression ... 43

Table 5.2.1 Baseline characteristics of the Lebanese university students by gender ... 47 Table 5.2.2 Bivariate analysis of BDS-22 score among Lebanese university students ... 48 Table 5.2.3 Mean and frequency distribution of BDS-22 score and BMI among all Lebanese university students and by gender ... 49 Table 5.2.4 Logistic regression of BDS-22 score with BMI categories for the study sample, overall and stratified by gender... 49

Table 5.3.1 Baseline characteristics of the participants by gender ... 50 Table 5.3.2 Descriptive Statistics and reliabilities of the study measures ... 51 Table 5.3.3 Correlation between study measurements in the overall sample and stratified by gender ... 52 Table 5.3.4 Linear regression analysis of the association between BMI, Body Shape

Dissatisfaction and BDS-22 ... 54

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DEDICATION

This thesis is dedicated to the soul of my mother who encouraged me to be the best I can be, to have high expectations and to fight hard for what I believe. She always provided me with best opportunities in life. I feel that she is always with me supporting and guiding. Thank you for your selfless and endless love and may God grant you his highest paradise.

To my husband Hazar and the two lovely roses, my daughters Nour and Sara, who have decorated my life and made it full of happiness and joy. To you, I owe where I stand today.

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ACKNOWLEDGEMENTS

In the name of Allah the most gracious and merciful, first and foremost, I praise God, the almighty for providing me this opportunity and granting me the capability to proceed successfully.

This thesis appears in its current form due to the assistance and guidance of several persons. I would therefore like to offer my sincere thanks to all of them.

To begin with, I would like to express my cordial thanks to my esteemed promoter, Professor Isabelle Godin, for accepting me as a PhD student. I greatly appreciate your excellent assistance, warm encouragement, thoughtful guidance, and critical comments.

I am also especially grateful for my co-promoter, Professor Pascale Salameh, for encouraging my research and for allowing me to grow as a research scientist. Your advices on my project have been priceless. I appreciate all your contributions of time, ideas, and assist to make my PhD experience productive and stimulating.

Furthermore, my sincerest gratitude is extended to the committee members of my thesis Dr. Philippe Donnen, Dr. Analysa Casini and Dr. France Kittel who have contributed immensely by their insightful comments and encouragement during the last three years.

Special thanks to Dr Nadine Saleh for her valuable feedback and statistical advices on my review paper.

I would also like to acknowledge and sincerely thank Proffesor Annie Robert and Dr. Hani Dimassi who accepted to take part of my defense jury. Your feedback and comments on my thesis manuscript are highly appreciated.

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am to all of you. Your prayers for me were what sustained me thus far. I would also like to thank my sisters and brother for their spiritual support in all aspects of my life. And most of all for my loving husband Hazar, I would like to express my deepest appreciation to him. Without your understanding, never-ending encouragement, and unconditional love, I would have never been able to complete my PhD.

Last but not the least, I would like to express my sincere gratitude and appreciation to my dearest friend Zeina with whom I walked the whole road. She was always beside me to incent me to strive towards my goal. I will never forget the hard moments we spent together.

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ABSTRACT

Background: Obesity has been identified as a global epidemic and is associated with

significant morbidity and mortality. Although obesity has been widely recognized for its consequences on physical health, its psychological burden in the adult populations remains unclear.

Objectives: Our purpose was to address the relationship between Obesity status and

psychological health within the adult young population in the Middle East and particularly in Lebanon (first aim). In addition, we intended to develop and validate a screening tool for the assessment of psychological distress (PD) in the obese young adult populations (second aim).

Methods: To achieve the first aim, three studies were conducted. The first study was a

systematic review and meta-analysis of observational studies that investigate the association between obesity and depression among adult populations in Middle Eastern countries. The second study was a cross sectional that aimed to explore the relationship between obesity and PD among the Lebanese University Students. The third study was conducted to examine the effects of actual body weight and body image on PD using a convenient sample of obese Lebanese young adults. The second aim was accomplished by conducting a fourth study to develop and validate a measure of PD related to obesity using three different samples of obese young adults.

Results: The systematic review identified eight observational studies from six countries of

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Lebanese university students, no evidence of a positive association was found between obesity and PD for both genders (Study 2). This result was confirmed in our third study in which body image dissatisfaction rather than obesity per se was associated with greater risk for PD. Finally, the “Obesity Specific Distress scale” (OSD) developed to measure distress in the obese young adult population demonstrated good psychometric properties regarding

internal consistency, test-retest reliability, and construct validity (Study 4).

Conclusions: Our meta-analysis suggests a positive association between obesity and

depression among adult population in the Middle East which appeared to be more marked among women. This is of public health significance and provides a framework for establishing policy interventions to diagnose and treat depression in obese adults. In Lebanon, young obese adults who suffer from body image dissatisfaction are at increased risk of PD. Public health interventions targeting PD at the population level may need to promote healthy attitudes towards body weight, body shape and self-acceptance, regardless of weight status. Finally, the developed instrument used to assess young obese persons with high risk of PD can help promote a better understanding of the association between PD and obesity. This might improve the outcome and provide the patients with more efficient treatment.

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RESUME

Contexte : L'obésité a été identifiée comme une épidémie mondiale et elle est associée à un

risque accru de morbidité et de mortalité. Bien que l'obésité soit largement connue pour ses conséquences sur la santé physique, son effet psychologique dans les populations adultes reste incertain.

Objectives: notre but était d'aborder la relation entre l’obésité et la santé mentale chez la

population adulte jeune du Moyen-Orient, en particulier au Liban (premier objectif). En plus, nous avons l'intention de développer et valider un outil de dépistage pour l'évaluation de la détresse psychologique chez les jeunes adultes obèses (deuxième objectif).

Méthodes: Pour réaliser le premier objectif, trois études ont été menées. La première a été

une revue systématique et une méta-analyse des études observationnelles qui examinent l'association entre l'obésité et la dépression chez les populations adultes dans les pays du Moyen-Orient. La deuxième a été une étude transversale qui vise à explorer la relation entre l’obésité et la détresse psychologique chez les étudiants de l'Université libanaise. La troisième étude a été menée pour examiner l’effet du poids actuel et l'image du corps sur la détresse psychologique en utilisant un échantillon de convenance de jeunes adultes libanais obèses. Le deuxième objectif de développement et validation d’une échelle de mesure de la détresse psychologique associée à l’obésité a été réalisé en utilisant trois échantillons différents d’adultes jeunes obèses.

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et la dépression (Rapport de cote =1,27; intervalle de confiance à 95% 1,11 à 1,44) qui semble être plus marquée chez les femmes que chez les hommes (étude1). Chez les étudiants des universités libanaises, aucune évidence d’une association positive n’a été trouvée entre l’obésité et la détresse psychologique pour les deux sexes (étude 2). Ce résultat a été confirmé dans notre troisième étude dans laquelle l'image de l'insatisfaction corporelle plutôt que le poids excessif en soi a été associée à un risque accru de détresse psychologique. Enfin, l'échelle “Obesity Specific Distress” développée pour mesurer la détresse de la population adulte jeune obèse a démontré de bonnes propriétés psychométriques concernant la cohérence interne, la reproductibilité et la validité conceptuelle (étude 4).

Conclusions : Notre méta-analyse suggère une association positive entre l'obésité et la

dépression parmi la population adulte dans le Moyen-Orient qui semblait être plus marquée chez les femmes. Ceci est d'une importance pour la santé publique et fournit un cadre pour l'établissement des interventions politiques pour diagnostiquer et traiter la dépression chez les adultes obèses. Au Liban, les adultes jeunes obèses qui souffrent de l'insatisfaction de l’image du corps sont à risque accru de détresse psychologique. Les interventions de santé publique ciblant les détresses psychologiques au niveau de la population peuvent avoir besoin de promouvoir des attitudes saines à l'égard du poids corporel, la forme du corps et de l'acceptation de soi, indépendamment du statut de poids. Enfin, l'instrument développé utilisé pour évaluer les personnes jeunes obèses avec un risque élevé de détresse psychologique peut aider à promouvoir une meilleure compréhension de l'association entre détresse psychologique et l'obésité. Cela pourrait améliorer les résultats et fournir aux patients un traitement plus efficace.

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LIST OF ORIGINAL PAPERS

Studies of this thesis have been published in the following journal:

1) Obesity and Depression among Adults in the Middle East: A Systematic Review and

Meta–analysis. Linda Abou Abbas, Pascale Salameh, Wissam Nasser, Zeina Nasser,

Elias Elias, Isabelle Godin. Clinical obesity journal 5(1), 2-11.

doi:10.1111/cob.12082.

2) Body Mass Index and Psychological Distress among Lebanese University students:

Examining the moderating effect of gender. Linda Abou Abbas, Pascale Salameh,

Wissam Nasser, Zeina Nasser, Isabelle Godin. International Journal of Adolescence and Youth, 2015: p. 1-9.

3) Development and Initial Validation of a Brief Scale for Assessing Psychological

Distress in Obese Adults. Linda Abou Abbas, Pascale Salameh, Zeinab Mansour,

Zeina Nasser, Elias Elias, Isabelle Godin. Clinical Epidemiology and Global Health. doi: http://dx.doi.org/10.1016/j.cegh.2015.08.001.

4) Body Image and Psychological Distress among Obese Adults: A Cross- Sectional

Study. Linda Abou Abbas, Pascale Salameh, Zeinab Mansour, Zeina Nasser, Elias

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LIST OF ABBREVIATIONS

AGFI Adjusted Goodness of Fit Index

ANOVA Analysis of variance

BDS-22 Beirut Distress Scale

BMI Body Mass Index

BSQ Body Shape Questionnaire

CFA Confirmatory Factor Analysis

CFI comparative Fit Index

CI Confidence Interval

CINAHL Cumulative Index to Nursing and allied health literature

CMA Comprehensive Meta-analysis

CVI Content validity for item

Df Degree of freedom

DSMIV Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition

EAT Eating attitude test

EFA Exploratory Factor Analysis

GFI Goodness of Fit Index

HPA Hypothalamic pituitary adrenal axis

I2 Inconsistency index

ICC Intra class coefficient

IPFM Income-per-family-member

IQR Interquartile range

IRB Institutional Review Board

IWQOL-Lite Impact of weight on quality of life

Kg Kilogram

KMO Kaiser-Meyler-Olkin

KSA Kingdom Saudi Arabia

MET Metabolic Equivalent Total

Min Minute

NOS Newcastle-Ottawa scale

OR Odds Ratio

OSD Obesity Specific Distress Scale

PD Psychological Distress

RMSEA Root-mean-square error of approximation

SD Standard deviation

SPSS Statistical Package for Social Sciences

UAE United Arab Emirates

USA United states of America

WC Waist circumference

WHO World Health Organization

WHR Waist to hip ratio

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THESIS STRUCTURE

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CHAPTER 1 INTRODUCTION

In the past few decades, obesity has become a major public health concern worldwide [1]. The World Health Organization (WHO) has labeled obesity as the “new epidemic” of the 21st century. According to a global estimate by the WHO, in 2014, more than 1.9 billion adults were overweight with 600 million meeting the criteria for obesity and by 2015, the numbers would be approximately 2.3 billion and 700 million respectively [2].

Obesity is defined as “a condition of abnormal or excessive fat accumulation in adipose tissue, to the extent that health may be impaired”[3]. A variety of methods have been developed for assessing body fat. The use of the most reliable techniques such as Magnetic

Resonance Imaging, Computerized Tomography, or Dual‐energy X‐Ray Absorptiometry are

restricted by their expense and unfeasibility in large epidemiological studies [4]. Therefore, practical methods, based on measurements or ratios of different body parts, have been developed to estimate the body fat. Of these, Body mass index (BMI) and waist circumference (WC) are the most common surrogate methods used in epidemiological research and clinical settings to assess body fat [5]. BMI calculated as body weight in

kilograms divided by the square of body height in meters (kg/m2), is recommended as a

practical and reliable approach for assessing body fat as compared to the Dual‐energy X‐Ray Absorptiometry method [6, 7]. The WHO has classified overweight and obesity in adults based on various BMI cutoffs. For adults 18 years or older, overweight is defined as BMI

between 25 and 29.9 kg/m2, and obesity as BMI of 30 kg/m2 or higher [3]. These

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several chronic diseases [9]. The way it is calculated is by drawing the circumference at the middle way between the iliac crest (hip bone) and the costal margin (lower rib). According to the National Cholesterol Education Program’s Adult Treatment Panel Standard (NCEP-ATPIII), abdominal obesity is reached when WC measures more than 102 cm in males and 88 cm in females [10].

Although obesity is assumed to affect mostly modern western societies characterized by sedentary lifestyles and excessive food consumption, obesity epidemic is not restricted to developed countries. The Middle East, a region that includes western Asia and some parts of North Africa, appears to be no exception with its overall obesity prevalence among adults reaching alarming levels (24.5%) [11] similar to those reported from European countries such as the United Kingdom (22.9%) and Germany (26.3%) [12]. The major behavioral transitions emphasized by the replacement of traditional diet into westernized food pattern, the increasingly sedentary lifestyle as well as other social and cultural factors have been identified as main contributors to the high prevalence of obesity and its comorbidities in Middle Eastern countries [11].

Lebanon, a small Arab country lying on the cross roads of the Eastern Mediterranean basin and the Arab hinterland, has particularly faced a rapid increase in obesity in the last two decades. Studies on adult population in Lebanon showed that obesity prevalence rates have increased during the past decade from 17% in 1997 to 28.2% in 2009 [13] approaching those reported from developed countries such as the USA where 32.2% of the adult population are reported as obese ( BMI ≥ 30 kg/m2

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prevalence of obesity among Lebanese adults is expected to approach 40% by the year 2020 [17].

Obesity has been linked to a significantly greater incidence of chronic diseases including type II diabetes, cardiovascular disease, hypertension, dyslipidemia, stroke, respiratory problems, osteoarthritis, and certain forms of cancer (endometrial, breast, and colon) [18]. The aftereffect of this obesity related association is premature mortality. Every 5 kg/m2 increase in BMI above the optimal range of 22.5-25 kg/m2 was associated with a 30% increase in all-cause mortality (40% for vascular; 60-120% for diabetic, renal, and hepatic; 10% for neoplastic; and 20% for respiratory and for all other mortality) according to a study conducted by Whitlock et al [19]. In addition, a recent study conducted in nine selected countries of the Middle East has reported that the increase in obesity epidemic has paralleled the rise in the prevalence of many non-communicable diseases such as diabetes, cardiovascular diseases and cancer [20].

Besides its tremendous effect on physical health, the economic cost of obesity is staggering. By 2006, spending on obesity-related medical costs accounted for an estimated 86 billion dollar a year in the USA [21]. Given this backdrop, it is not surprising that the physical impact of obesity has received a great deal of attention, but important questions arise about the psychological impact of obesity. More recently, the emphasis has shifted to looking at the relationships between obesity and psychological distress (PD).

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and behavioral problems (e.g., increased substance abuse, sleep disruption, poor work perform) [24]. These subjective states can reduce the emotional resilience of individuals and impact their social functioning [25] and ability to cope with a particular set of circumstances [26].

PD is perceived as harmful and covers a wide range of health related phenomena [27, 28] leading to biological dysfunction [29], and social suffering [25]. PD may even lead to higher premature mortality rates [30]. On the other hand, PD is associated with higher risk of developing clinically diagnosable mental disorders [31]. Thus, PD is considered an important indicator of mental health status as it causes psychological, social and functional impairments and satisfies the diagnostic criteria for a psychiatric disorder.

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difficult to draw generalized conclusions. Recent studies have reported that obesity is associated with detrimental mental health consequences only in subgroups of obese individuals such as those suffering from body image dissatisfaction [38].

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2510 obese patients aged 37 to 57 years seeking professional treatment [46]. The second “Obesity-Related Problems scale” (OP scale) was developed in the Swedish Subject Study (SOS) specifically to assess psychosocial problems related to obesity [47]. Unfortunately, no valid measure of PD related to obesity was founded and adapted to the sociocultural characteristics of the obese general adult population in the Middle East.

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CHAPTER 2 LITERATURE REVIEW

In this dissertation, a review of literature investigating the psychological correlates of obesity particularly depression, anxiety and PD is presented. Body image concept definition, methods used for the assessment of body image dissatisfaction, identification of factors which may contribute to the development of a negative body image in western societies as well as findings of available research on body image in Middle Eastern countries are presented. Finally, the possible mechanisms explaining the relationship between obesity and PD were elucidated.

2.1 The psychological impact of obesity

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attributions toward life events) and eating/dieting behaviors such as dietary restraint and binge eating. Stratifying individuals according to these moderating or mediating factors may help to explain some of the inconsistent findings arising from previous literature. The last generation of their studies proposed to explore the causes of obesity by incorporating different scientific fields such as genetic, physiological and psychological components, and to assess their interaction and the underlying relations between the diverse risk factors [32].

Despite the bulk of support indicating a lack of relationship between obesity and mental health, several systematic reviews and meta-analysis have demonstrated the opposite, suggesting the presence of significantly higher levels of depression and anxiety in the obese adult population. All reviews that have investigated the association between obesity and both depression and anxiety will be addressed in the following section.

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analysis showed higher odds of anxiety disorders in obese compared with non-obese individuals (OR=1.40, 95% CI: 1.23-1.57), with no differences between women and men [52].

These aforementioned systematic reviews were based mainly on studies with cross sectional design and illustrate first and second generation studies of the psychological impact of obesity. In the last two decades, a substantial number of longitudinal studies have examined the association between obesity and depression. Although these studies cannot establish causal relationship between obesity and depression, but they can provide a better understanding of this association over time. Luppino et al. performed a meta-analysis with 15 prospective studies that assessed the bidirectional association between obesity and depression. A reciprocal link between obesity and depression was found: Obese persons had a 55% increased risk of developing depression over time, whereas depressed persons had a

58% increased risk of becoming obese. Studies from the United States produced stronger

associations than studies from European countries (OR=2.12 versus OR=1.33; P-value 0.05). There was no significant sex difference in these associations (OR=1.31 in men and OR=1.67 in women; P-value 0.81) [53].

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reported in others [55]. A closer review of the published literature on the association between obesity and PD underscores the fact that divergent findings were often the result of methodological inconsistencies. For instance, covariates used for adjustment in statistical models varied immensely, and few studies have controlled for the most known confounding factors such as age, gender, presence of chronic disease, smoking status and physical activity. Another possibility is that other factors rather than the obesity status per se may be causally related to PD or mediates the association between these two concepts. Identification of such factors is crucial and may partly explain why pervasiveness inconsistencies exist in the published literature. One of these factors is body image particularly body shape dissatisfaction and weight perception [32]. Research has revealed that the risk of PD might rise due to weight perception rather than the actual body weight [54], other suggest that body image mediates the association between obesity and PD [38].

An extensive review of published literature on the association between obesity and psychological functioning in the adult population of Middle Eastern countries revealed that depression accounted for the majority of research, followed by anxiety. Thus far, no studies have been conducted in Middle East countries to investigate the association between obesity and PD.

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2.2 Body image

2.2.1 Definition of Body image concept

Body image is a multidisciplinary approach projecting subject’ own perceptions and feelings toward their physical appearances [59]. There are two types of body image disturbances: Perceptual and Attitudinal. The first involves over or underestimation of body size while the second entangles dissatisfaction with body shape or size. Perceptual disturbance can occur when a persons’ self-perception deviates too far from the ideal standard. Thus, negative body image perception might reflect the conflict between perception and reality. The difference between an individual’s perception of his/her current body size and ideal body shape is related to body satisfaction. Therefore, the wider the inconsistency between an apparent and a desired body shape is, the greater the body dissatisfaction [33].

2.2.2 Body image assessment in obese adults

Various methods for body image assessment exist, including computer morphing [60], video projection [61], and static figure or figural drawing scales[62]. However, perceptual and attitudinal aspects of body image are often assessed via well validated self-reported questionnaires [62]. This review will cover instruments most relevant for the particular appearance concerns of obese individuals (i.e, body weight and shape). These include the Body Shape Questionnaire and the Multidimensional Body-Self Relations Questionnaire.

Body Shape Questionnaire (BSQ) is a self-report measure of body shape dissatisfaction

valuing the obsession with body form (size and shape) and its generated distress. It can be applied among different clinical populations of obese subjects [63].

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Multidimensional Body-Self Relations Questionnaire (MBSRQ) appraises subjects’ manner

toward their own weight, their gratification and affect regarding their body image and their general health and fitness level [44].

2.2.3 Body image dissatisfaction and its associated factors

In the last few decades, body image dissatisfaction has become widespread among the western hemisphere even doubling in figures among females (25 to 56%) between 1972 and 1997 and tripling for men during the same period (15 to 43%) [64]. Major dissatisfactory factors were waist to abdomen ratio and body weight [65]. Moreover, body image dissatisfaction seriousness has been associated more to therapy inquirers obese subjects than among non-obese population. A range of factors including sex, age and BMI were the most prominent factors to affect body image among the western cultures [65]. In Sarwer et al. paper, it was revealed that waist/abdomen ratio was the most displeasing factor for body image dissatisfaction [66].

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Provided that ideals of both genders are a long way from overweight, it is reasonable to state that body weight plays a major role in body image satisfaction. Both females and males expressed dissatisfaction when overweight compared to their non-overweight. Moreover, overweight female uttered more dissatisfaction than their equivalent overweight males [70].

The bulk of research regarding body image pivoted around young females since it peaks as a self- awareness issue during the early teenage years. A study led by Tiggeman and Lynch (2001) revealed a decrease in appearance concerns and body dissatisfaction [71]. On the other hand, comparable to women, men showed decline in body appearance preoccupation as they get older [72].

In general, three main motives characterized by family, media and friends affect subjects’ approach and insight to body image [73]. In fact, media influence has a prevailing effect on female body appearance. Indeed, several studies exposed an association between the amount of audiovisual media and commercial magazine exposure and level of body discontent [74]. Males look have been less enquired in the media compared to women, nevertheless, masculine oriented magazines are crammed with well-dressed muscular men [75] along with sparsely covered thin figure females with considerable breasts [66]. This reflects the desire of the western societies towards their own body shape.

On the other hand, Middle Eastern studies regarding the body image subjects are scant. Studies reveal a healthier body image compared to their western counterpart [76, 77] and are more likely to consent their real body shape with no wish to change [78]. This could be explained by the Middle Eastern societal belief of a relation between a full-figured body shape and fecundity [79].

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females who strive to have an unrealistic slim figure. While a bulky part (66.1%) anticipated weight shedding, most of the participants fell within the overweight or obese category. Moreover, a small percentage (12.7%) of the obese and overweight subjects preferred weight gain [78].

Another study comparing a population of college students in Jordan and the United States showed that the first group was healthier in terms of body image compared to the American group [80]. Other Middle Eastern cultures reported healthy body attitudes. For example, Iranian women had greater body esteem than American women in a study by Akiba due to lack of contact and exposure with western civilization and the thin ideal [76]. Nonetheless, investigations revealed that influence of western culture exposure on Middle Eastern feminine population having damaging effects. Westernized Arab college females were more likely to be affected by eating disorders than their native Egyptian based counterpart [81]. Soh et al. found that Saudi women subjected to western values had more body image disturbance than girls less exposed to Western culture [82].

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Despite lack of research investigating body image among Middle Eastern feminine populace, less is explored regarding male image. Akiba et al. published a study concluding a less preoccupation of Iranian man with their body image compared to their American counterpart [76]. In addition, Ford et al. deduced that Egyptians males are satisfied with their figure and desire no change [84].

Possible explanations for the ambiguity in Middle Eastern body image include the increasing Westernization and also the nutrition transition in the developing world [85]. Many younger Middle Easterners are internalizing Western media and beauty ideals, and beginning to eat more like Westerners along with the increasingly sedentary lifestyle, leading to a greater prevalence of overweight and obese individuals who are aware that their bodies do not match the thin ideal, causing them distress [85]. Nevertheless, older generations and some individuals from the younger generations are hanging on to traditional Arab values, creating conflict and uncertainty regarding body image among some Middle Eastern samples.

2.3 Plausible mechanisms for the association between obesity and PD

Several potential biological and psychosocial mechanisms influencing the course of the association between obesity and PD has been addressed in the published literature [86, 87].

2.3.1 Biological mechanisms

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marked by the hormone cortisol and endogenous opioids hypersecretion, can motivate those individuals to increase their food consumption, particularly high-calorie meals, as a way to cope with their stress [92-94]. Consequently, this may contribute to body fat accumulation.

2.3.2 Psychosocial mechanisms

Psychological mechanisms that link obesity to PD are also likely to be involved. Several studies have reported that obese individuals experience stigma and discrimination from their personal body appearance [95] as a result of the continuous exposure to negative messages across media that promote the more acceptable and unattainable slender ideal body shape [35]. For instance, an analysis of obese and non-obese characters in popular television programs have shown that the obese television characters are more often the object of jokes and less likely to be portrayed as leaders and in romantic relationships [96]. Consequently, obese individuals may react to weight stigma by internalizing negative messages about themselves which make them feel psychologically distressed [37, 97]. Obese subjects are also ostensibly to be bullied compared to non-obese. When applying to job opportunities, obese subjects are prone for discriminatory and have a diminished chance for a position compared to non-obese individual. All in all, daily life on obese people can be a potential struggle, dealing with a constellation of stigmatization and discrimination, which can accumulate in a sort of bad experiences leading to a rise of mental health troubles, offering a justification of the reason for PD behind obesity [36, 98].

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Research has revealed that the risk of PD might rise due to body shape dissatisfaction rather than the actual body weight. These findings provide striking evidence to the powerful nature of the body image dissatisfaction that can accompany obesity. Internalizations of messages regarding slender ideal body shape, specified and elucidated by mass media, cultural traditions and stances of close members, can lead to intense feelings of body dissatisfaction and the development of PD among obese individuals. In addition, some researchers have argued that the recent obesity media coverage may perpetuate an assumption that being obese is risky and harmful in many respects. Internalization of such beliefs may not necessarily encouraged to better weight control, but can negatively affect obese people's self-image and thereby increase the risk of PD.

2.4 Summary of Findings

A literature review was undertaken to explore and stipulate what the impact of obesity might be on the psychological health of adults particularly depression, anxiety and PD, be it positive, negative or null. The findings of previous research studies contradict each other. In addition, the available literature is marked with methodological problems. On the other hand, a complex association between obesity and psychological health particularly depression, anxiety and PD appears to exist, and importantly, obese individuals constitute a heterogeneous population, making it very difficult to draw generalized conclusions.

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In the last few decades, a growing body of literature has begun to focus on the experience of body image among obese populations in western societies. Research has revealed that the risk of PD might rise due to body shape dissatisfaction rather than the actual body weight, other suggest that body image mediates the association between obesity and PD. In Middle Eastern countries, no studies have been conducted to investigate the association between obesity and PD taking into account the effect of body image. In our thesis, we intend to focus on the effect of body image on the obesity-PD relationship among adult population.

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CHAPTER 3 STUDY AIMS AND HYPOTHESES

3.1 General aims

Given the increasingly alarming rates of obesity in the Middle East and particularly in Lebanon, investigating the relationship between obesity and psychological health is crucial. In addition, identification of obese individual experiencing distress is of particular interest for public health and clinical practice. A critical step in the development of this area is to establish psychometrically sound measures that assess PD relevant to obesity status. Accordingly, the overarching aim of the thesis was to broaden our knowledge regarding the association between obesity and psychological functioning in the Middle East and particularly in Lebanon. We also sought to develop a brief self-reported measure of distress related to obesity in the Arabic language suitable for screening and validated for use in the Lebanese obese young adult population.

3.2 Specific aims and hypotheses

3.2.1 Exploring the association between obesity and psychological health in the Middle East and particularly Lebanon

Aim1: As depression accounted for the majority of studies that investigate the association

between obesity and psychological functioning in the Middle East, we conducted a systematic review and meta-analysis of observational studies that examined the relationship between obesity and depression among the adult population in Middle Eastern countries.

Hypothesis 1: It is hypothesized that obesity is associated with depression among the adults

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In Lebanon, as in most Middle Eastern studies, studies investigating the association between obesity and PD are scarce. This led us to believe that it would be of value to study this phenomenon in depth. Accordingly, we explored the association between these two constructs using two different samples of Lebanese young adults.

Aim2: We examined the relationship between obesity and PD among Lebanese University

students and test the moderating effect of gender on this association.

Hypothesis 2: It is hypothesized that obesity is associated with PD.

Hypothesis 3: It is hypothesized that the association between obesity and PD would differ by

gender such that relationships would be stronger for women than men.

Aim3: In the second data set of community based sample of obese young adults, we

reexamined the association between BMI and PD taking into account the effect of body image particularly body shape dissatisfaction.

Hypothesis 4: Negative body image rather than obesity per se is associated with PD.

3.2.2 Development and validation of a scale for PD assessment in the obese adult population

This broad aim was achieved in two steps.

Aim 4: The first step consisted of the development of a questionnaire for PD measures

adapted to the socio-cultural characteristics of the Lebanese obese young adult population. We also sought to validate the content validity of the developed tool.

Hypothesis 5: The developed tool will show appropriate content validity as a measure of PD

in the obese adult population.

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addition to confirming its reproducibility and clinical validity. Secondary aims included examination of obesity class differences on the developed scale. In line with these aims, we tested five main hypotheses.

Hypothesis 6: predicted that the developed scale will be internally reliable.

Hypothesis 7: The developed scale is correlated with other similar generic instruments. Hypothesis 8: Scores of the developed scale will be higher among obese patients suffering

from depression compared to functioning individuals.

Hypothesis 9: We expected that scores of the scale will increase across obesity classes.

3.3 Significance of the Research

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CHAPTER 4 METHODS

4.1 Overview

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4.2 Obesity and depression among Adults in the Middle East

A systematic review and meta-analysis were performed in accordance with the Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA 2009) guidelines [99]. A statement of ethics was not required.

4.2.1 Search strategy

A systematic literature search of PubMed, Ovid Medline, Cochrane, Embase and Cumulative Index to Nursing & Allied Health Literature (CINAHL) was performed for studies published in peer-reviewed journals up to April 2014. The databases were searched using the keywords of 'obesity', 'overweight', 'metabolic syndrome', 'adiposity', 'body weight', 'body mass index', 'BMI', 'waist-hip-ratio', 'waist circumference', 'intra-abdominal fat', 'abdominal obesity', 'excess weight', 'depression', 'depressive symptoms', 'mood disorder', 'depressed mood', 'major depressive disorder', 'MDD', 'psychological disorder', 'psychological distress', 'psychiatric disorder', 'mental disorder', 'Middle East', 'Bahrain', 'Egypt', 'Iran', 'Iraq', 'Jordan', 'Kuwait', 'Lebanon', 'Oman', 'Palestine', 'Qatar', 'Saudi Arabia', 'Syria' , 'Turkey', 'United Arab Emirates', and 'Yemen'. Keywords were combined using the Boolean operators “OR” and “AND”. The search was conducted with no language restrictions and was limited to human studies. Bibliography lists from all eligible articles were also hand searched to identify additional papers potentially relevant for inclusion.

4.2.2 Selection criteria

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literature scope revealed that there is substantial methodological heterogeneity between studies for defining depression, therefore no pre-specified restriction criteria for the assessment of depression on psychometrics or via clinical diagnoses were adopted for study inclusion. Studies on children, adolescents, women during pregnancy or postpartum, patients with somatic diseases (such as diabetes, hypertension, polycystic ovary syndrome) were excluded from the review. Moreover, studies where odds ratio (OR), as an estimate measure for the association between obesity and depression, was not available and could not be calculated were not included.

4.2.3 Data extraction and synthesis

Search, identification of studies eligible for inclusion and extraction of data were performed by three independent reviewers. Any disagreements were resolved by discussion and cross checking the papers. For each paper, detailed information was collected on: basic study information (last author’s name, publication year, and country), basic sample characteristics (sample size, age and gender), study design, obesity and depression assessment, covariates adjusted for in the analysis and the association estimates. Where more than one adjusted OR was reported, we chose the OR with the highest number of adjusted variables.

4.2.4 Methodological quality assessment

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maximum of one star was awarded for each item within the selection and exposure/outcome assessment category. A maximum of two stars was allocated for the comparability of groups on the basis of the design or analysis. For case-control studies, stars were distributed within the selection category over the adequacy of the case definition, representativeness of the cases, selection of controls, and definition of controls. Within the exposure category, stars were given for the ascertainment of exposure, similar method of ascertainment for cases and controls and non-response rate. For cross-sectional studies, stars were distributed within the selection category over the representativeness of the sample, selection of the non-exposed participants and ascertainment of exposure. According to the adapted NOS scale, a maximum of nine stars can be allocated for high quality case-control studies, and a maximum of 6 stars can be obtained for high quality cross-sectional studies. The NOS scale has not yet established a definite cut-off point for assessing the quality of the studies that used this scale. It is commonly considered that a study is of “high quality” when it scores 60% or above of the maximum allowed score [53, 102, 103]. Accordingly, case-control studies of 6 or more stars and cross sectional studies of 4 or more stars are considered “high quality” studies.

4.2.5 Statistical analysis

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of heterogeneity, respectively [107]. Stratified analysis by study design was performed in order to assess whether results differed across designs. P-values less than 0.05 were considered statistically significant. Subgroup analyses were carried out to identify possible sources of heterogeneity between studies and to check for the potential effect of gender, assessment of obesity and of depression, control of confounding, and quality of study on the association between obesity and depression. The fixed effect model was used to determine any significant differences in the effect sizes between subgroups. To evaluate the undue influence of individual studies on the pooled estimate, we performed sensitivity analysis by omitting one study at a time from the meta-analysis. Additional sensitivity analysis was undertaken by excluding studies that included underweight individuals in the obesity reference group from the analysis to evaluate their impact on the pooled estimate. The possibility of publication bias was visually inspected by a funnel plot in which the log ORs were plotted against their standard errors [108] and was further tested by Egger’s test for funnel plot asymmetry (significance level at P-value < 0.05) [109]. Publication bias occurs whenever the research that appears in the published literature is systematically unrepresentative of the population of completed studies. Funnel plot is a scatterplot of the component studies in a meta-analysis. An asymmetric funnel plot or a hole around the null hypothesis value in funnel plot suggests missing effects, so the existence of publication bias. The statistical software Comprehensive Meta-analysis (CMA) version 2.0 was used to perform all data analyses [110].

4.3 Body Mass Index and Psychological Distress among Lebanese University students

4.3.1 Study design and participants

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is observational and respects participants’ anonymity and confidentiality, the Internal Review Board (IRB) of the Lebanese university waived the need for an official approval. Students were informed through a written and oral consent form that their participation was voluntary and they had the right to refuse to participate. Pregnant female students were not included in the study sample. Out of 4900 distributed questionnaires, 3384 (69.1%) were returned to the field worker. Students with missing information about BDS-22, weight or height were excluded from the analysis (566 of 3384 eligible students). A total sample of 2818 students was used. Additional study details have been previously described [111].

4.3.2 Data collection

The questionnaire used for data collection was composed of several parts:

- Socio-demographic characteristics include: age, gender, place of residence (Beirut, Mount Lebanon, North, South and Bekaa), type of University (private or public university), marital status (single, married, divorced or widowed), and income-per-family-member (IPFM). IPFM, a measure defined as the household monthly income of a family divided by number of its members. Subsequently, the IPFM was classified into 4 categories (low, medium low, medium high and highest income).

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- Questions about health indicators: Students were asked to rate their health ('How would you describe your current health status') on a ten point scale. Students were also questioned about the presence or absence of chronic diseases.

- PD measurement: PD was assessed using the Beirut Distress Scale (BDS-22) [114] which is a validated tool designated to measure PD for the Lebanese young population. Respondents were asked to rate how often, in the past few weeks, they experienced several PD symptoms. The 22 items are answerable on a Likert scale from 0 indicating no experience of the symptoms to 3 indicating that the experience of the symptoms are severe (0- never, 1- sometimes, 2- often, and 3- always) with possible score from 0 to 66. The BDS-22, a measure created by adding all the items of the score, ranged from 0 to 66 with higher scores indicating greater risk of PD. The BDS-22 has been found to be a valid and reliable tool among Lebanese young adults [114]. In the present study, Cronbach’s alpha was 0.93 indicating high internal consistency. Provided that the lifetime prevalence of any DSM-IV (Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition) disorder was

29.1% of the young adult population [115], the BDS-22 was dichotomized at the 75th

percentile, with a score of 25 or more being indicative for high risk of PD.

- Anthropometric measures: The weight and height measures of the total students were self-reported. For a randomly selected subsample of 507 students, the weight and height were measured by interviewers using a calibrated balance and a stadiometer (without shoes). These subsample anthropometric measurements were used to validate and correct the self-reported height and weight of the total sample. Accordingly, BMI, calculated as weight in kilograms divided by height in meters squared, was used as categorical variable. Consistent with the definitions set forth by the WHO, students were grouped into four categories: 'underweight' (BMI <18.5 kg/m2), 'normal weight' (BMI 18.5–24.9 kg/m2) as a reference

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4.3.3 Statistical analyses

Data entry and analyses were performed using the statistical software SPSS version 20.0. All analyses were conducted on a weighted sample using the distribution of students in private and public Lebanese universities, provided by the Centre for Educational Research & Development. Simple regression equations were generated to validate the self-reported height and weight values by the measured ones in the subsample of students (n=507); correlation

coefficients along with paired t-test were performed in that case. The predicted values were

then used as corrected weight and height. As the validity of self-reported height and weight may differ among men and women, separate analyses were made for each sex.

For males:

Measured Weight = 1.001* self-reported weight – 0,782 (r = 0.969; p < 0.001). Measured Height = 0.825* self-reported height + 30.651 (r = 0.855; p < 0.001). For females:

Measured Weight = 0.962* self-reported weight + 2.391 (r = 0.958; p < 0.001). Measured Height = 0.938*self-reported height + 10.043 (r = 0.937; p < 0.001).

There were strong correlations between measured and self-reported values in weight and height for both men and women (Spearman's correlation for men and women respectively: 0.969 and 0.958 for weight and 0.855 and 0.937 for height). Men statistically significantly over-reported their weight and height by 0.71 kg and 0.66 cm respectively. While, women under-reported their weights by 0.2 kg and over-reported their heights by 0.2 cm.

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percentages. Statistical bivariate analysis was performed. Spearman test was used to correlate between continuous variables. The Pearson chi-square (χ2) test was used for categorical variables. Group differences were compared using student T test and Kruskal-Wallis tests. A p-value<0.05 was considered statistically significant. A multivariate analysis using logistic regression was carried out with the higher risk for PD as the dependent variable. Adjusted odds ratios and their 95% CIs were reported. The final logistic regression model was reached after ensuring the adequacy of our data using the Hosmer and Lemeshow test. The generated final model was tested for the effect modification by gender as it is believed that women and men may express PD differently [118] and have different BMI levels [119].

4.4 Body image dissatisfaction and Psychological Distress among Obese Young Adults in Lebanon

This was a cross sectional study conducted in a convenience sample of obese adults selected over the period June to September 2014. The participants were university students and subjects working at different type of institutions in Beirut. Subjects eligible for the study had to be of either gender, 18 years of age or older, and had a BMI ≥ 30 kg/m2. Pregnant women as well as individuals with psychiatric illnesses were excluded from the study. Since the study was observational and respected participants’ anonymity and confidentiality, the Internal Review Board (IRB) of the Lebanese university waived the need for an official approval; however, researchers and field worker conducted the study according to the research ethics guidelines laid down in the Declaration of Helsinki.

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questionnaire including information about socio-demographic characteristics (age, gender, marital status, level of education, and income per family member), health-related lifestyle factors (cigarette smoking status), weight and height measurements, and three standardized questionnaires namely the Beirut Distress Scale (BDS-22), the Body Shape Questionnaire (BSQ-16), and the Eating Attitude Test (EAT-26).

4.4.2 Study measurements

1) PD was assessed using the BDS-22 (described previously).

2) BMI Based on participants’ self-reported height and weight, BMI was calculated as

weight in kilograms divided by height in meters squared.

3) Body image dissatisfaction: Body image dissatisfaction was assessed using the

BSQ-16 questionnaire that measures dissatisfaction with body size and shape [120]. The 16 items are answerable on a 6 point Likert scale ranging from “never” to “always” with possible score ranging from 16 to 96. Higher scores indicate greater risk of body shape dissatisfaction.

3) Eating attitude disorder test (EAT-26) which consists of 26 items that measure a broad range of symptoms characteristic of abnormal attitude towards food and eating. The test is scored using a six Likert scale with a choice of six answers ranging from `always’ to `never’ with possible score from 6 to 156. Higher scores are generally considered as indicative of increased risk for disordered eating behavior.

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analysis was performed. The student T-test was used for the continuous variables to compare their means. The Pearson chi-square (χ2) test was used for categorical variables. We explored the internal consistency of each test and the correlations between them. Multiple linear regression analyses were performed to evaluate whether BMI and BSQ-16 significantly predicted PD in the overall sample and stratified by gender. Two models were evaluated: the association between BMI and PD was first examined (Model 1). Next, a second model, including the main effects of BMI and BSQ-16, was tested (Model 2). The two models were adjusted for age, gender, current cigarette smoking status and eating test attitude (EAT-26). Finally, the moderating effect of gender on the association between BDS-22 and both BMI and BSQ-16 was tested in the adjusted model using interaction terms. A p-value<0.05 was considered statistically significant. Linearity of the relationship, the normality of distribution of residuals, and the non-colinearity of retained variables were insured before the models were accepted.

4.5 Development and initial Validation of a Brief Scale for Assessing Psychological Distress in Obese Young Adults

4.5.1 Item generation and development of the OSD questionnaire

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responses to be weight-specific. Items of the scale were translated and adapted to the Arabic language by three independent professional translators. Backward translation procedures were applied to all items of the scale. Translators were asked to avoid literal translation and to use a simple and acceptable language for the Lebanese adults. Translation inconsistencies were resolved by consensus in collaboration with the investigators. The initially proposed version of the OSD questionnaire was designed to be self-completed with a 5-point Likert-type response format ranging initially from “never” to “always”.

4.5.2 Content validity

Content validity of the resulting version was assessed by a panel of three experts who were not involved in the initial item development (two researchers with experience in development and validation of instruments and one psychiatrist). Experts were asked to rate the relevance of each item on a 4-point Likert scale from 1 “not relevant” to 4 “very relevant”. Content validity for each item (CVI) was calculated as the number of experts rating either three or four (quite relevant and very relevant, respectively), divided by the total number of experts. All items with a CVI rating of 0.8 or above are considered to indicate good content validity [123]. Six items on the draft were deemed to be invalid because they yielded CVI less than 0.8 and were removed from the questionnaire.

4.5.3 Pilot study

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The factor structure of the OSD scale was initially tested using a convenience sample of adult obese individuals (Sample1 N=180) visiting fitness centers and obesity private clinics in Beirut between January and August 2013. Following the scale set up, the OSD structure was further tested using another convenience sample of obese individual (sample2 N=200) between June and August 2014. The participants were students recruited from public and private Lebanese universities, and subjects with diverse professions recruited in different public and private institutions. In both samples, eligible subjects were at least 18 years of age, could speak and read the Arabic language fluently, and had a BMI ≥ 30 kg/m2. Pregnant or lactating women as well as individuals with chronic diseases such as hypertension, diabetes mellitus, adrenal glands disorders and thyroid diseases were excluded from the study. There were no significant differences in terms of age and gender between the two samples (P-value>0.05). The scale was also administered to a third sample of obese patients for clinical validation. Since the study was observational and respected participants’ anonymity and confidentiality, the Internal Review Board (IRB) of the Lebanese university waived the need for an official approval; however, researchers and field worker conducted the study according to the research ethics guidelines laid down in the Declaration of Helsinki.

4.5.4 Sample size calculation

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4.5.5 Procedure

Participants were informed in writing and orally that participation was voluntary and they had the right to refuse to participate. In the exploratory phase, participants (N=180) were asked to complete a standardized questionnaire that included questions regarding demographic characteristics (age, gender), body weight and height, and the 18-item OSD draft questionnaire.

In the confirmatory phase, participants (N=200) completed another questionnaire including information regarding demographic characteristics (age, gender), body weight and height, the constructed scale and a battery of self-report questionnaires that assess impact of weight on quality of life (IWQOL-Lite) [127], Body image dissatisfaction (BSQ-34) [63], and PD (Beirut Distress Scale, BDS-22) [43] for convergent validation.

For clinical validation, two psychotherapists orally administered the scale to their patients (N=50) suffering from depressive disorders due to their obesity status.

To assess test-retest reliability of the scale, 54 obese individuals of the first sample answered the questionnaire twice. The time between test and re-test reproducibility examination averaged approximately 14 days.

4.5.6 Assessment Measures

Impact of weight on quality of life (IWQOL-lite): The IWQOL-lite is a 31-item self-report

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Body Shape Questionnaire (BSQ-34): The BSQ-34 is a self-report questionnaire measuring

body shape dissatisfaction. It is a useful measure for assessing preoccupation and distress with body shape and size in clinical samples of obese individuals. The 34 items are answerable on a 6 point Likert scale ranging from “never” to “always” with possible score ranging from 16 to 204. The score is obtained by adding the 34 items. Higher scores indicate greater degree of body shape dissatisfaction. The questionnaire has demonstrated good validity and reliability [63].

Beirut Distress Scale (BDS-22) [129]: described previously.

Anthropometric measurements: Weight and height were self-reported. BMI was calculated

using weight (in kilograms) divided by the square of height (in meters). BMI was categorized as follows: obesity class I (BMI 30−34.9 kg/m2

), obesity class II or severe obesity (BMI 35-39.9 kg/m2) and obesity class III or morbid obesity (BMI ≥ 40 kg/m2) [116].

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factor loadings (<0.40), low communalities (h2<0.5), or high cross-loadings were considered for elimination [132].

A Confirmatory Factor Analysis (CFA) was further conducted to test hypotheses about the factorial structure of observed variables using the maximum likelihood method. Goodness of fit was determined by commonly used fit indices, including the relative χ2

/df <5, root-mean-square error of approximation (RMSEA) < 0.06, comparative Fit Index (CFI) > 0.90, the Goodness of Fit Index (GFI) > 0.90 and the Adjusted Goodness of Fit Index (AGFI) > 0.90 [133]. Cronbach’s alphas were calculated to assess internal consistency. A coefficient of above 0.7 indicated a good internal consistency [134].

The total OSD scale was obtained by adding up the scores of individual items. Higher OSD score reflects greater level of distress. Scores for each dimension of the scale were also calculated by adding their constituent items.

Test-retest reliability was assessed through the intra-class correlation coefficient (ICC; average measure) for the global scale and its subscales. A good reproducibility was noted when ICC > 0.7 [135].

Convergent validity using Spearman correlation was assessed to evaluate whether total OSD scale and its subscales were associated with BSQ-34, IWQOL-Lite, and BDS-22 scores.

Clinical validity was also tested by comparing the means of the clinical sample (N=50) to those of functioning individuals (Sample 1), using the Student test for means comparison.

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CHAPTER 5 RESULTS

The results of research hypotheses are displayed in this Chapter.

5.1 Obesity and Depression among Adults in the Middle East

5.1.1 Study selection strategy

Figure 5.1.1 illustrates the flowchart of study selection process. The literature search identified a total of 806 records. After exclusion of duplicate records and non-relevant abstracts, 23 published studies were retained. Of these, 15 studies did not meet our eligibility criteria for study inclusion and were excluded after reviewing their full text. Consequently, a total of eight full-text studies were included in quantitative synthesis and meta-analysis [136-143].

5.1.2 Study characteristics

The characteristics and results of the eight included study papers in our review are described in Table 5.1.1. Papers were published on five different countries of the Middle East namely, Iran, Turkey, Jordan, Lebanon and Syria between the years 2007 and 2013. A total sample of 12641 adults aged 17 and over was included in the meta-analysis. Six studies recruited both men and women participants, while two studies included only women. Five studies had a cross-sectional design and the others were case-control. Obesity was assessed in terms of BMI (≥30 Kg/m2

) or measured WHR (cut-off for women ≥ 0.84). BMI was either

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5.1.3 Quality assessment

The results of the quality assessment of the included studies using the NOS scale are summarized in Table 5.1.2. The cross-sectional studies received three to five stars out of a maximum score of six. The case-control studies were awarded one to 5 stars out of nine. According to our quality criteria on the NOS scale, four cross sectional studies were found to be of high quality, whereas the case-control studies were of low quality.

Literature identified through database search

(n = 793)

Records after duplicates removed (n = 761)

Tittle & abstracts screened (n =761)

Additional records identified from other sources

(n =13)

Full-text articles assessed for eligibility (n =23)

Studies excluded for non-relevance (n=738)

Full-text articles excluded when (n=15):

• Obesity measures treated as continuous variables (n=5) • Overweight and obese participants pooled in the analysis (n=3) • Samples included adolescents (n=3)

• Obese patients suffered co-morbid conditions (n=1)

• Sample included participants pooled from ineligible countries (n=1) • Letter to the editor (n=1)

• Odds ratio not available and could not be calculated (n=1)

Final selected studies for quantitative synthesis and meta-analysis (n=8) (5 cross-sectional and 3 case-control studies)

Obesity and Psychological Distress in Young Adults

Co-supervision thesis

For the degree of Doctor

Université Libre de Buxelles

School of Public Health

And

Lebanese University

Doctoral School of Sciences and Technology

Speciality: Public Health, Epidemiology

Obesity and Psychological Distress in Young Adults

Jury Members

TABLE OF CONTENTS

LIST OF FIGURES

LIST OF TABLES

DEDICATION

ACKNOWLEDGEMENTS

ABSTRACT

RESUME

LIST OF ORIGINAL PAPERS

LIST OF ABBREVIATIONS

THESIS STRUCTURE

CHAPTER 1 INTRODUCTION

CHAPTER 2 LITERATURE REVIEW

CHAPTER 3 STUDY AIMS AND HYPOTHESES

CHAPTER 4 METHODS

CHAPTER 5 RESULTS