5 Clinical Trials for Various Conditions
The investigators previous studies have shown that obese and non-obese individuals respond differently to daily intake of snack food. The purpose of this study was to determine whether these differences are specific to high energy density snack foods. The investigators hypothesized that obese individuals would show an increase in motivation to obtain high energy density snack foods after two weeks of daily consumption, but that non-obese women and obese women consuming low energy density foods would have reduced motivation to consume snack foods after two weeks of daily consumption.
The obesity epidemic continues to be a major public health concern, with 38% of US adults and 17% of children obese. One factor that has been highlighted as a robust predictor of weight outcomes is the relative reinforcing value (RRV) of food, or how rewarding one finds eating compared to alternative activities. An emerging body of literature has built upon the observed relationship between the RRV of food and weight by hypothesizing that the promotion of alternative reinforcers, or rewarding activities that could take the place of eating, offers a novel approach to decreasing excess energy intake and combatting obesity. We aim to integrate distinct bodies of literature and fill a gap in the evidence by testing whether parenting intervention messages delivered and practiced in the context of shared activities can decrease the RRV of food by making parent-child interactions more rewarding. The ultimate goal of this research is to demonstrate that such an intervention can increase children's motivation to interact with their parent instead of eating a favorite food, demonstrating the potential for positive parent-child interactions to become an alternative source of pleasure.
The goal of this project is to identify predictors of success in the treatment of obesity after bariatric surgery. The specific aims of this proposal are to: 1. Employ behavioral tests of mechanisms that control food intake in normal weight individuals, to determine which intake control mechanisms lead to changes after Roux-en-y gastric bypass (RYGB) or sleeve gastrectomy (SG); and 2. Measure behavioral and psycho-social predictors of weight loss and food intake reduction, so as to determine which are most predictive of successful weight loss and food intake reduction. 3. Account for success in reduction of food intake brought about by the pattern of hormone release, particularly glucagon-like peptide-1 (GLP-1), Peptide YY (PYY) and gastric distention, known to underlie satiation, coupled with post-ingestive changes in reinforcing value of food and motivation to consume. Tests of the hypothesis will be done by measuring responses to tasting, working for, and consuming, foods on sensory, motivational, cognitive, and physiological variables, including amount consumed and rate of eating under standardized conditions, before surgery and at a two year follow up visit. In addition, the inhibitor sitagliptin will be administered the night before and day of test meal and exendin-9-39 (EX9) will be infused before and during the meal to determine whether blockade of GLP-1 / PYY receptors after surgery reverses intake reduction. Investigators predict that successful patients will show changes that favor reduction in food intake, rate of eating, motivation to consume, reward value of foods, and a hormone profile that has been shown to generate satiation and maintain reduction in intake (e.g. increased Cholecystokinin (CCK), GLP-1, PYY, reduced ghrelin). To the extent that psycho-social and cognitive factors may override physiological brakes to eating behavior, the subjects may fail to achieve success, and consequently the failure may be predicted from over-impulsiveness or inability to suppress working for rewarding food stimuli. To test these hypotheses, a total of 83 patients will be enrolled prior to RYGB/SG and restudied 2 years after the surgery. The sitagliptin / EX9 studies will be done in a subset of 32 completers. To test this aim, patients will be divided into 4 groups of 19. The 4 patients from each group with the most weight loss (% weight loss ≥35 at 2 years post-surgery, 16 patients in total) and least weight loss (% weight loss of ≤25 at two years 16 patients in total) will be recruited for these two additional post-operative visits within one year of completing Visit #3 after the RYGB/SG surgery. A total of 32 patients will be recruited for visits 4 and 5.
This study aims to determine the relationships among loss of control eating, restriction, relative reinforcing value of high energy-dense food, and obesity risk. In order to achieve this aim, the investigators will follow children over the course of a year, obtaining behavioral and observational measurements, in addition to a two-week restricted access and two week non-restricted access period.
The purpose of this study is to research the effects of exercise on calories eaten and expended. The investigator expects to find out whether subjects change their eating and activity behaviors when starting an exercise program.