THE EFFECTS OF AGE ON POSTPRANDIAL THERMOGENESIS AT 4-GRADED ENERGETIC CHALLENGES - FINDINGS IN YOUNG AND OLDER WOMEN

There remains controversy over the effect of age on postprandial therm ogenesis, with some studies observing decreased postprandial thermogen esis in older subjects and other studies finding no effect of age. We investigated this issue in 8 young (25.2 +/- 1.8 years) and 8 older (7 2.2 +/- 2.1 years) healthy glucose-tolerant women with normal thyroid hormone status. Repeated measures of the thermic effect of feeding (TE F) were obtained following consumption of test meals containing 0, 104 6, 2092, and 4184 kilojoules (kJ) by using indirect calorimetry. TEF a t each meal size was determined once in the older subjects and twice i n the younger subjects (during follicular and luteal phases of the men strual cycle) for a total of 96 measurements. There was a positive dos e-response between meal size and TEF (p < .001) that was not significa ntly affected by age group. The best single predictor of TEF expressed as a percentage of meal energy content,vas waist-to-hip ratio (R-2 = .416, p < .02). These results indicate that aging is not associated wi th decreased TEF in the absence of factors such as a hypothyroid state or glucose intolerance.