Role of physiology and environmental factors on food intake control in boys

Abstract

To examine the hypothesis that physiologic regulation of short-term food intake (FI) in boys is affected by the interaction between physiological and environmental factors, four studies were conducted. The primary objectives were as follows: (i) to compare the effect of glucose and whey-protein (50 g) preloads on satiety and FI as affected by time to the next meal and body composition in normal weight (NW) and obese (OB) boys; (ii) to examine the role of short-duration physical activity on subjective appetite and to identify the role of and associations between fitness and FI at a pizza lunch 30 min after glucose and whey-protein drinks in NW boys; (iii) to determine the effect of television viewing (TVV) on FI of boys at a meal and its effect on caloric compensation at the test meal after a premeal glucose drink; and (iv) to determine the reproducibility of short-term FI and subjective appetite after a glucose preload, ventilation threshold (VT), and body composition assessed by bioelectrical impedance analysis (BIA). Obese boys responded less than NW boys to whey protein, with time (30 vs. 60 min) to the next meal the response decreasing to glucose but increasing to protein. Subjective appetite was increased by short-duration physical activity and FI following glucose and whey-protein preloads was positively associated with VT in boys. TVV while eating a meal contributed to increased energy intake by delaying normal mealtime satiation and reducing satiety signals from previously consumed foods. Short-term FI after a glucose preload, subjective appetite after glucose and physical activity, VT, and body composition assessed by BIA were reproducible in boys. In conclusion, physiologic regulation of short-term FI in boys was affected by the interaction between physiological and environmental factors. Macronutrient source, body weight and composition, time to the next meal, short-duration physical activity and fitness, and TVV at mealtime impacted on FI regulation in boys.