EFFECT OF DIET-INDUCED WEIGHT LOSS ON PYY LEVELS: A PILOT STUDY

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This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Obesity is becoming a major health issue in the United States. In a few years obesity is predicted to surpass smoking as the primary cause of preventable death. Investigators have recently discovered that the peptide PYY3-36 (PYY) regulates food intake by reducing appetite and increasing a sense of fullness after meals. Obese individuals have substantially lower baseline levels of endogenous PYY than lean individuals. Because PYY reduces appetite, it is hypothesized that postprandial PYY concentrations will be higher in subjects who successfully lose weight compared with those who do not lose weight. Some studies have reported greater weight loss on a low carbohydrate as compared with a low-fat diet in overweight and obese individuals. It is also proposed that dietary composition will influence PYY levels, both acutely and after weight loss. Some studies have suggested that attrition rates in weight loss programs are lower in subjects who ingest low carbohydrate diets compared with subjects who ingest low fat diets. This lower attrition rate may be due to fewer hunger signals. Therefore, it is also hypothesized that subjects who lose weight on a low carbohydrate diet will have higher levels of PYY than subjects who lose weight on a low fat diet. This study will be conducted in two phases. Phase 1 will evaluate whether the macronutrient composition of meals affects postprandial PYY concentrations in obese individuals acutely. Phase 2 of the study will evaluate whether successful diet-induced weight loss affects postprandial PYY concentrations in obese individuals.