Human aging is often associated with compromised regulation of energy balance and inappropriate body weight and body composition. Among adults older than 60 years, about 38% are overweight, 15% are obese, 20% are underweight, and 20-50% have sarcopenia. Safe and effective therapies to help elderly people maintain a healthy body weight and composition are sought. Liquid foods elicit weaker appetitive and dietary responses than solid foods. Thus, the ingestion of energy-yielding liquids might help underweight elderly people increase energy intake and body weight, while the ingestion of solids should be more satiating and help overweight elderly people maintain or lower body weight. Research also shows that resistive exercise and training influence the regulation of energy balance and help prevent or treat sarcopenia. Limited data indicate that resistive training influences the dietary response to nutrient supplementation in elderly people, and that these responses might be different when the supplement is consumed in liquid vs. solid form. This proposal entails three studies designed to more fully document the differential dietary responsiveness to energy-yielding liquids vs. solids in 65-90 year-old men and women who are sedentary or perform resistive exercise, to examine potential contributory mechanisms, and to test the therapeutic application of this knowledge. Study 1 will contrast the acute effects of liquid and solid food ingestion, coupled with resistive exercise, on satiation, satiety, and feeding. Study 2 will document potential mechanisms to explain findings from Study 1 through exploration of gastrointestinal influences of liquid and solid loads on certain physiological regulators of satiety (i.e., insulin, leptin, cholecystokinin, glucagon-like peptide, apolipoprotein A-IV, ghrelin, glucose, and gastrointestinal transit time). Study 3 will assess the clinical implications of the chronic intake of liquid vs. solid nutritional supplements on appetite, dietary intake, energy expenditure, body weight, body composition, and selected metabolic and endocrine regulators of feeding and energy balance. The testing of these novel hypotheses regarding differential responses to energy-yielding liquid and solid foods in sedentary and resistive-exercised elderly people will provide a strong foundation for integrative recommendations to promote safe and effective weight changes in elderly people. ? ?
