Age-Related Differences in the Appetite-Regulating Hormone Response to Exercise

Acute exercise alters appetite-regulating hormones like peptide tyrosine tyrosine (PYY), glucagon-like peptide-1 (GLP-1), and ghrelin, suppressing appetite and reducing food intake. The effect of exercise on hunger and satiety has been shown to vary by body composition, sex, and habitual physical activity, but the influence of aging is less understood.

We aimed to examine age-related differences in the effect of acute exercise on appetite-regulating hormones.

Participants from 2 age cohorts (younger adults, 19-29 y, n = 39; older adults, 65-75 y, n = 29) completed 2 45-min study conditions on separate days in randomized order: 1) an exercise bout (60% $\dot{V}$ O_2peak) on a bicycle ergometer (Exercise), and 2) a seated rest period (Rest). Plasma concentrations of PYY 3-36 (PYY3-36), GLP-1, and acylated ghrelin, as well as subjective perceptions of hunger, fullness, thirst, and nausea (via visual analog scales), were measured before a standardized snack (fasted) and before and after a subsequent exercise/rest condition.

Exercise induced a greater increase in PYY3-36 relative to Rest in younger adults compared to older adults (difference: 26.6 pg/mL; 95% confidence interval (CI): 3.4, 49.8 pg/mL; P = 0.025). GLP-1 concentrations were consistently greater in older adults independent of the study condition (Exercise/Rest; all P < 0.001), but the GLP-1 response to exercise did not differ by age group (P = 0.456). Similarly, exercise responses in acylated ghrelin (P = 0.114) and subjective appetite perceptions (all P ≥ 0.288) did not differ between younger adults and older adults.

The present study showed age-related differences in the appetite-regulating hormone response to 45 min of nonfasted, moderate-intensity exercise in PYY3-36 but not GLP-1 or acylated ghrelin. The age-related variations did not translate into differences in subjective hunger or fullness.