March 13, 2010
Exploring Diabetes’ Link To Eating Disorders
July 20, 2009
The presence of friends increases food intake in youth [Obesity and eating disorders]
Background: Friendship may be uniquely relevant and influential to youths' eating behavior.
Objective: This study examined how overweight and nonoverweight youths adjust their level of eating as a function of their familiarity with their eating partner.
Design: Twenty-three overweight and 42 nonoverweight youths had the opportunity to play and eat with a friend (n = 26) or with an unfamiliar peer (n = 39). The dependent variables of interest were the amount of nutrient-dense and energy-dense foods children consumed and their total energy intake.
Results: Participants eating with a friend ate substantially more than did participants eating with an unfamiliar peer. Furthermore, overweight youth, but not nonoverweight youth, who ate with an overweight partner (friend or unfamiliar peer) consumed more food than did overweight participants who ate with a nonoverweight eating partner. Matching of intake was greater between friends than between unfamiliar peers.
Conclusions: These results extend previous research by suggesting that the effect of the partners' weight statuses may add to the facilitative effect of familiarity and result in greater energy intake in overweight youth and their friends. Behavioral similarity among overweight youth may increase the difficulty of promoting long-term changes because the youths' social network is likely to reinforce overeating. This trial was registered at clinicaltrials.gov as NCT00874055.
Severe obesity is associated with novel single nucleotide polymorphisms of the ESR1 and PPAR{gamma} locus in Han Chinese [Obesity and eating disorders]
Background: A large number of potential obesity loci have been reported. At least 18 genes have been replicated in a minimum of 5 studies on obesity-related phenotypes. Fourteen additional genes have been associated with obesity in Asians.
Objectives: Our objectives were to examine how many common variants of these candidate genes are associated with severe obesity in Han Chinese and how they are combined to exert their effects.
Design: In total, 304 severely obese patients [body mass index (BMI; in kg/m2) ≥39] and 304 control subjects (BMI ≤ 24) participated in a 2-staged association study. Subsequently, 220 additional severely obese patients (BMI ≥ 35) and 338 controls (BMI ≤ 24) were recruited to replicate the results. All of the controls were age-, sex-, education- and residence-matched. Finally, a pooled analysis was carried out based on all 514 cases and 606 controls with complete information.
Results: The first-stage association analysis in 94 cases and 94 controls found 18 potentially associated single nucleotide polymorphisms (SNPs) (P = 0.01–0.1). The significance of 3 novel common SNPs, 1 on ESR1 and 2 on PPAR, were confirmed in the second stage and replicated further with odds ratios ranging from 1.89 to 2.24. The combined effect of these 3 genes was stronger (odds ratio: 5.27; 95% CI: 2.25, 12.32) than that from any individual gene.
Conclusions: Severe obesity in Han Chinese was associated with 3 novel common SNPs for ESR1 and PPAR. These 2 genes collectively result in a >5-fold risk of severe obesity. This information may contribute to the assessment of risk of severe obesity.
The relative reinforcing value of food predicts weight gain in a longitudinal study of 7-10-y-old children [Obesity and eating disorders]
Background: The relative reinforcing value (RRV) of food, defined as how hard an individual is prepared to work to gain access to food rather than a nonfood alternative, has been shown to be higher in obese adults and children than in their normal-weight counterparts. However, these cross-sectional studies are unable to determine whether a high RRV of food is predictive of adiposity change or whether it is a consequence of being obese.
Objective: The objective was to examine the association between the RRV of food and 1-y weight gain in children aged 7–10 y.
Design: An observational longitudinal study design was used. The RRV of food was determined by using a questionnaire method at baseline when the children (n = 316) were aged 7–9 y. Adiposity [body mass index (BMI), BMI SD score, fat mass index, waist circumference, and waist circumference SD score] was assessed at baseline and after 1 y.
Results: Regression analyses indicated that the RRV of food was not associated with any measure of adiposity at baseline or at the 1-y follow-up (all P > 0.58). Changes in BMI (B = 0.06, P < 0.001), BMI SD score (B = 0.03, P = 0.001), and fat mass index (B = 0.09, P = 0.001) after 1 y were significantly predicted by the RRV of food at baseline.
Conclusions: The RRV of food predicted the change in adiposity over a relatively short-term period of 1 y and thus may be associated with the development of obesity. The lack of association in cross-sectional analyses indicates that this behavior is a risk factor for weight gain, although weight differences may not emerge until later childhood.