THE EFFECTS OF SHORT-TERM OVERFEEDING ON INTAKE

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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. The goal of the proposed research project is to gain a better understanding of the effects of short-term overfeeding on intake and feeding behavior in individuals who are prone to obesity as compared to individuals who appear to be resistant to obesity in our current environment of excessive intake and reduced activity. Obesity is a serious and growing public health problem in the United States. The biological processes that underlie this increasing prevalence of obesity have not been clearly defined but likely involve faulty interactions between environmental factors (excess food intake and reduced physical activity) and biological systems of weight regulation in individuals who are genetically "at risk." Individuals who are genetically predisposed to being lean in our current environment may be able to sense and respond to excess caloric intake more rapidly and accurately than those predisposed to obesity. As compared to obese prone individuals, obese resistant individuals will sense the positive energy balance associated with 3 days of overfeeding more effectively as manifested by higher ratings of satiety, lower ratings of hunger and desire to eat and reduced spontaneous food intake following overfeeding. It is hypothesized that obese resistant individuals will respond to 3 days of overfeeding by sensing the excess calories more effectively than obese prone individuals, as manifested by higher ratings of satiety, lower ratings of hunger and desire to eat and reduced spontaneous food intake following overfeeding. The end result is that these mechanisms will protect lean individuals from excessive weight gain. To test these ideas, intake studies on obese resistant and obese prone individuals after a control diet and after a 3-day period of overfeeding (50% excess caloric intake per day) are proposed. Specifically, studies on the effects of overfeeding on the ad-libitum energy intake and measures of hunger and satiety will be performed. These studies will provide insight into the biology that predisposes to weight gain and regain and will lay the groundwork for future studies of the abnormalities that exist in obese and pre-obese individuals.