BLOOD-GLUCOSE AND HORMONAL RESPONSES TO SMALL AND LARGE MEALS IN HEALTHY-YOUNG AND OLDER WOMEN

Blood glucose regulation in the fasting and fed states has important i mplications for health. In addition, the ability to maintain normal bl ood glucose homeostasis may be an important determinant of an individu al's capacity to regulate food intake. We tested the hypothesis that a ging is associated with an impairment in the ability to maintain norma l blood glucose homeostasis following the consumption of large meals b ut not small ones, a factor that could help to explain age-related imp airments in the control of food intake and energy regulation. The subj ects were Eight healthy younger women (25 +/- 2 years, SD) and eight h ealthy older women (72 +/- 2 years), with normal body weight and gluco se tolerance. Following a 36-h period when diet and physical activity were controlled, subjects consumed test meals containing 0, 1046, 2095 and 4184 kJ (simulating extended fasting, and consumption of a snack, a small meal, and a moderately large meal), with 35% of energy from f at, 48% from carbohydrate, and 17% from protein. Each subject consumed each of the test meals on a separate occasion. Serial Blood samples w ere collected at baseline and during 5 h after consumption of the meal s. Measurements were made of circulating glucose, insulin, glucagon, f ree fatty acids, and triglycerides. There was no significant differenc e between young and older women in their hormone and metabolite respon ses to fasting and consumption of the 1046-kJ meal. However, following consumption of 2092 and 4148 kJ, older individuals showed exaggerated responses and a delayed return to premeal values for glucose (p =.023 ), insulin (p =.010), triglycerides (p =.023), and the ratio of insuli n to glucagon (p =.026). In conclusion, these results suggest an impai rment in the hormonal and metabolite responses to large meals in older women.