Habitual physical activity differentially affects acute and short-term energy intake regulation in young and older adults

Background: Energy intake (EI) regulation is impaired in older adults, but it is not known if habitual physical activity affects accuracy of EI regulation in older compared with young adults. Objective: We hypothesized that the ability to compensate for a high-energy yogurt preload beverage at a subsequent ad libitum meal (i.e. acute compensation) and over the course of the testing day (i.e. short-term compensation) would decrease with age, but the magnitude of the decline would be smaller in physically active compared with sedentary older adults. Design: On two occasions, young active (n = 15), young sedentary (n = 14), older active (n = 14) and older sedentary (n = 11) subjects consumed either a high-energy yogurt preload beverage (YP: 500 ml, 1988 kJ, men; 375 ml, 1507 kJ, women), or no preload (NP), 30 min before an ad libitum test meal. EI at both ad libitum meals was measured, and total daily EI was determined on both testing days. Percent EI compensation for the YP was calculated for the test meal and testing day to determine acute and short-term compensation. Results: Percent EI compensation at the test meal was significantly lower in the older compared with the young subjects (65 +/- 4 vs 81 +/- 4%, P = 0.005). There was no effect of habitual physical activity level on acute compensation, and no age by physical activity level interaction (P = 0.60). In contrast, short-term compensation was not different with age (87 +/- 5 vs 93 +/- 6%, older vs young, P = 0.45), but was more accurate in active vs sedentary subjects (100 +/- 5 vs 79 +/- 6%, P = 0.01). As with acute compensation, there was no age by physical activity interaction (P = 0.39). Conclusion: Acute EI regulation is impaired in older adults, which is not attenuated by physical activity status. However, EI regulation over the course of a day is more accurate in active vs sedentary adults, which may facilitate long-term energy balance. Future work is needed to determine if higher energy expenditure in older active vs older sedentary adults improves long-term EI regulation.