Obesity is a medical condition, in which the fatty tissue stored in the body in the form of a natural energy reserve, exceeds healthy limits. Clinically, obesity is defined as an excess accumulation of adipose tissue resulting in a Body Mass Index (BMI) of greater than 30 Kg/m2. Obesity can be classified into three different types, based on the BMI; Class I (BMI: 30-34.9), Class II (BMI: 35-39.9), and Class III (BMI: >40). The prevalence of obesity has sharply increased over the past few decades. Among adults, the prevalence has increased from 15% in the 1970s to over 32% in 2003-2004. Additionally, more and more kids are affected with this condition each year. Studies estimate that anywhere between 5 to 25% of kids in developed countries are obese. A lot of this increase in prevalence rates is due to changes in lifestyle, most notably, dietary changes and decrease in activity. Obesity, in turn, leads to increased susceptibility to many other disorders. These include disabilities arising from the increased body mass, such as osteoarthritis, sleep apnea, and psychological disorders, as well as disorders resulting from the metabolic changes associated with the excess fat, such as hypertension, diabetes mellitus, cardiovascular diseases, and certain cancers. Morbidity due to obesity is fairly high.
Treatment of obesity is aimed at achieving and maintaining a healthy and optimum weight. Strategies to help reach this target include lowering the total calorie intake, exercising for about 30 minutes at least 3-4 times a week, and undertaking a behavior modification program under a psychologist or a therapist. In extreme cases, where it is difficult to control obesity with these measures, surgery may be required. A gastric bypass surgery is the most favored choice for extreme obesity. This surgery involves making the stomach and the intestine physically smaller, so that the individual feels full more quickly. However, a program involving a healthy diet and exercise needs to be strictly followed post-surgery.
There is strong evidence supporting the theory that obesity develops as a result of an interplay among various environmental and genetic factors. Individuals with a family history of obesity are more susceptible to gaining weight. In fact, risk of obesity is double, triple, or five times greater if a first degree relative is overweight, moderately obese, or severely obese, respectively.
Linkage studies have identified several different loci that are associated with obesity. The most important of these include the POMC (Proopiomelanocortin) locus (chromosome 2) identified in a Mexican American study, loci on chromosomes 1, 3, 6, 11, 18, and 20, identified in the Pima Indian community, GLUT2 (Glucose Transporter 2) and Adinopectin on chromosome 3, GLUT4 (Glucose Transporter 4) and PPAR Alpha (Peroxisome Proliferator-Activated Receptor-Alpha) on chromosome 17, and the GAD2 (Glutamic Acid Decarboxylase 2) gene on chromosome 10p11-12. In some Finnish families, obesity was found linked to a locus on chromosome XQ24. Suspected candidate genes at this locus include the genes AGTR2 (Angiotensin II Receptor, Type 2), SLC6A14, and SLC25A5. In addition, certain rare forms of obesity have been found to be caused by mutations in single genes. Six such genes have been identified, which include Leptin, Leptin Receptor, and the Melanocortin 4 Receptor (MC4R) genes.
Obesity may also be a clinical feature in many syndromes, genetic in nature. Examples of such syndromes include Prader-Willi syndrome, Bardet-Biedl syndrome, Alstrom syndrome, Cohen syndrome, and Albright Hereditary Osteodystrophy.
Clement et al. (1998) reported a mutation in the human leptin receptor gene, a G>A transition at the +1 position of intron 16, that causes obesity and pituitary dysfunction. The splice site mutation results in skipping of exon 16, which leads to a truncated protein of 831 amino acids lacking both the transmembrane and intracellular domains. The mutation was discovered in homozygosity in a consanguineous Kabylian Berber family from northern Algeria in which 3 of 9 sibs had morbid obesity with onset in early childhood. The affected sisters had normal birth weights, but developed severe obesity in the first months of life. They showed abnormal eating behaviors resembling those seen in Prader-Willi syndrome and in individuals with anatomic damage of the hypothalamic area; behavior included fighting with other children for food, impulsivity, and stubbornness. Psychologic testing showed emotional lability and social disability, but no mental retardation. Core temperature and glucose metabolism were normal, as were ACTH and cortisol, but growth hormone and thyrotropin levels were low. The girls did not spontaneously develop puberty and had low estradiol, LH, and FSH levels consistent with central hypogonadism. Clement et al. (1998) considered their results to indicate that leptin is an important physiologic regulator of several endocrine functions in humans.
Jackson et al. (2007) used three different BMI-for-age references to compare between adolescent overweight and obesity among girls in Egypt, Kuwait, and Lebanon. Egyptian adolescents were found to have an intermediate percent of obesity (11.2%, 11.2%, and 13.5%), lower than that of Kuwaiti girls, but higher than the Lebanese, in all three references. [See also: Kuwait, Lebanon > Jackson et al., 2007].
Lafta and Hayyawi (2006) conducted a cross-sectional study on four medical centers in the city of Baghdad between 2002 and 2003, to understand the social aspects of obesity. The total study sample consisted of 400 adult Iraqi subjects (209 males, 191 females), and was selected from among people attending the clinics with BMI > 30 Kg/m2. A questionnaire regarding lifestyle, history, and social behavior was used to obtain data from the subjects. The most common form of obesity was Class I type (59%), followed by Class II (24%), and Class III (17%). Among all classes, the peak age of obesity was seen at 40-49 years. A significant relation was noticed between BMI and gender. Males constituted more of Class I obesity cases (59%), while females numbered more in the Class II (57%) and III groups (58%). Other factors significantly associated with obesity were marital age in the case of females, and a feeling of social acceptance. The social acceptance could be linked to the belief that obesity increases attractiveness. Major barriers to physical exercise in these patients were found to be a dislike for exercise (76%), lack of time (47%), laziness (26%), and embarrassment (25%). The obese were found to have ordinary social relationship and normal sexual relationship with their partners.
Halalsheh and Tarawneh (2000) tried to assess the association between osteoarthritis and obesity using a case control study. A total of 282 (female:male-1.7:1; mean age: 52.2 years) patients diagnosed with osteoarthritis (OA) of the knee were assessed for their body weight, height, and BMI. The results were compared with those of 282 age- and sex-matched controls. The patients with OA were found to have mean BMI in the Obese Class I category, while the controls fell into the pre-obese class. BMI was found to be significantly higher in the OA patients than in the controls. Although this difference was statistically significant in both sexes, it was more so in the females. Halalsheh and Tarawneh (2000) stressed the importance of patients with OA being encouraged to lose weight in order to decelerate disease progression.
Prevalence of overweight and obesity: Numerous studies were conducted to determine the prevalence of overweight and obesity in the Kuwaiti population. Al-Isa and Moussa (1998) studied the level of obesity among 7,419 Kuwaiti pre-school children aged 0-5 years. About 8% of this population was found to be obese, while about 4% were underweight. The Kuwaiti children were found to be heavier than their American counterparts, and heavier than a decade ago. Two years later, Al-Mousa and Parkash (2000) published highly valuable epidemiological data about overweight and obesity in 15,149 preschoolers, 10,130 six to nine-year-olds, 10,893 ten to thirteen-year-olds and 10,512 adolescents in Kuwait. Only in preschool children and adolescents obesity was higher in females and higher rates of overweight (and obesity) were observed in children aged (10-14) and (14-17). In the former group over 35% were overweight while in the latter 28% of boys and 31% of girls were overweight. This study also confirmed that obesity is on the rise in Kuwait. In a separate study, Sorkhou et al. (2003) surveyed 2,910 Kuwaiti children between the ages of 5 and 13-years and calculated the overall prevalence of obesity as 19.9%. In this study, obesity was more prevalent in the 9 to 13-year group (36.6%), compared to the 5 to 9-year group (9.1%). Badr et al. (2004) pointed towards an obesity epidemic in Kuwait. They studied a random sample of 504 male Kuwaiti first grade highschool students from urban, semi-urban, and rural settings. The subjects were administered a pre-tested questionnaire, and underwent the Eyzenck Personality Questionnaire. The overall prevalence of obesity and overweight was calculated at an alarmingly high rate of 44.4% for this population. Multivariate analysis found high neuroticism, large number of siblings, lack of exercise, and very low family income to be significant predictors of obesity and overweight. In 2004 also, Al-Isa published a study of 14,659 randomly sampled Kuwaiti school children between 10 and 14-years of age, and calculated the overall prevalence of overweight and obesity to be 30% and 14.7% among males, and 31.8% and 13.1% among females. The study also found that the BMI of Kuwaiti adolescents exceeded that of the Americans in each centile category. A later study by El-Bayoumy et al. (2009) among 5,402 children in the same age group (10-14 years) calculated the overall prevalence of overweight and obesity to be 30.7% and 14.6%, respectively. In this study also, the prevalence of overweight was slightly higher among females, while obesity prevalence was slightly higher among the males. Jackson et al. (2007) used three different BMI-for-age references to compare between adolescent overweight and obesity among girls in Kuwait, Egypt, and Lebanon. Kuwait adolescents were found to have the highest percent of obesity (12.2%, 13.5%, and 14.3%) in all three references. [See also: Egypt, Lebanon > Jackson et al., 2007].
Al-Isa (1997a, 1997b, and 2003) compared two independent cross-sectional samples of adult Kuwaiti nationals in 1980-81 (size=2,067) and 1993-84 (size=3,435). The results indicated a significant temporal increase in BMI (by 10 and 6.2% among men and women, respectively), prevalence of overweight (by 20.6 and 15.4% among men and women, respectively), and prevalence of obesity (by 13.7 and 8.4% among men and women, respectively). This increase was attributed to the effects of modernization, affluence, increased food consumption, and a sedentary lifestyle.
Factors associated with obesity: Several studies have also been performed on factors associated with obesity in Kuwait. In their study on Kuwaiti children aged 3-5 years, Al-Isa and Moussa (1999) found that male gender, age, region, parental education, birth order, dental status, eating regular meals, and socioeconomic status were factors associated with overweight and obesity. Another study, specifically on Kuwaiti college women by Al-Isa (1998), identified parental obesity, dieting, and the countries preferred to visit as being significant factors in determining obesity. Moussa et al. (1999) also found that family history of obesity, and diabetes mellitus, respiratory, and bone diseases in childhood were factors significantly associated with obesity.
Jackson et al. (2007) used three different BMI-for-age references to compare between adolescent overweight and obesity among girls in Lebanon, Kuwait, and Egypt. Lebanese adolescents were found to have the lowest percent of obesity (2.1%, 2.7%, and 2.7%) in all three references. [See also Egypt, Kuwait > Jackson et al., 2007].
Bener (2006) undertook a cross-sectional study among urban and semi-urban Qatari schoolchildren (aged 12-17 years) to determine the prevalence of obesity, underweight, and overweight in the country. A total of 1,968 boys and 1,955 girls (all Qataris) were enrolled in the study as the result of a multistage, stratified, random sampling process, and their BMI was calculated. Overweight and obesity were defined as over the 85th and 95th percentiles of BMI (International Obesity Task Force values), whereas underweight was defined as less than 5th percentile of BMI (CDC values). Data were processed using the SPSS package. Among the boys, the prevalence of underweight, overweight, and obesity was found to be 8.6%, 28.6%, and 7.9%, respectively, whereas among the girls, the values were 5.8%, 18.9%, and 4.7%. Age-wise split showed that the highest prevalence of obesity was at 12-years for boys (11.7%) and 13-years for girls (6.4%). Interestingly, among girls, obesity was found to be significantly higher among daughters of fathers who were at least university graduates. Mothers' education significantly affected the weight of sons. Considering the high prevalence of overweight and obesity among Qatari adolescents, Bener (2006) stressed the need for the establishment of a national program for the prevention and treatment of complications related to the condition.
El-Hazmi & Warsy, (2003) conducted a study which included 199 Saudi males and 258 Saudi females, to investigate the insertion/deletion (I/D) polymorphisms of the ACE gene in normal, overweight, and obese individuals. Of the 457 total individuals, 117 were categorized as obese, 185 as overweight, and 155 as normal, based on their BMI values. The frequency of DD genotype was 76.9%, 73.5% and 58.7% in the obese, overweight and normal groups, respectively. The frequency of ID genotype was 19.66%, 24.86% and 40% in the obese, overweight and normal groups, respectively. The frequencies of the D and I alleles in the obese individuals were 0.867 and 0.133, respectively. In the overweight individuals, the frequencies of these alleles were 0.859 and 0.141, respectively, while the frequencies were 0.787 and 0.213 in the normal weight individuals. The frequencies of the D allele were significantly higher in the obese and overweight individuals compared to normal individuals, suggesting that this allele may have a role in fat accumulation.
Daghestani et al. 2012 studied the association of the Arginine 16 Glycine (Arg16Gly) polymorphism in the beta2-Adrenergic Receptor gene with obesity in a Saudi population. 329 Saudi individuals (109 male and 220 female) participated in this case-control study. Obesity-related variables under measurement included glucose, lipid, insulin, and leptin levels, as well as body mass index (BMI), and waist/hip circumference and ratio; insulin resistance was measured using the homeostatic model assessment (HOMA-IR) method. Subjects exhibiting homozygosity for the polymorphism had significantly higher BMI, waist/hip circumference and ratio, cholesterol, triglyceride, LDL-C, HOMA-IR, and plasma leptin levels, than subjects containing the wild type allele. For all individuals, BMI as well as waist/hip circumference and ratio, had a significant correlation with cholesterol, triglyceride, and leptin levels. Glucose levels correlated significantly with all parameters for individuals exhibiting the homozygous wild type genotype; glucose levels correlated significantly with insulin resistance (HOMA-IR) for all genotypes. This study further supports the influence of the Arg16Gly polymorphism in the pathogenesis of obesity.
Chouchane et al. (2001) designed a case-controlled study to investigate the potential association of stress protein (hsp70-2) and TNF-alpha gene polymorphisms with obesity. A polymerase chain reaction followed by digestion with the endonuclease Pst I was used to detect a polymorphic Pst I site at position 1267 of the Hsp70-2 gene in 343 unrelated Tunisian patients with obesity and 174 healthy control subjects. Results revealed highly significant differences in genotypic distribution of this bi-allelic locus compared to the control subject group. Homozygosity for one hsp70-2 allele was highly associated with obesity. Chouchane et al. (2001) concluded that Tunisian individuals carrying the P2/P2 genotype of the hsp70-2 gene may have an increased risk of obesity.
Al-Safar et al. (2015) aimed to evaluate the association between TCF7L2 and PPAR-𝛾2 SNPs with Type 2 Diabetes Mellitus (T2DM) in the Emirati population and its relationship with obesity. The authors recruited 272 Emirati T2DM patients along with 216 healthy controls to the case-control study and carried out genotyping for the SNPs rs10885409 (TCF7L2) and rs1801282 (PPAR-𝛾2 Pro12Ala). No association was found between these two SNPs and T2DM in this cohort. The patients were then stratified based on obesity status wherein individuals with a BMI greater than 30 were considered obese. It was found that patients in the non-obese group with the TCF7L2 rs10885409 CC genotypes were at an approximately two-fold higher risk of T2DM than those with CT or TT genotypes [OR 1.975 (95% CI 1.127-3.461), p=0.017]. No such association was found in the obese group. The authors thus identified the rs10885409 C allele as a T2DM risk factor which is modulated by obesity status in the Emirati population.
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