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

Abstract

Background: 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.

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

Methods: 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.

Results: 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.

Conclusions: 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.

Keywords: aerobic exercise; aging; appetite; hormones; satiety.

FIGURE 1

Schematic overview of study design, illustrating the time points of blood collection. BL, baseline.

FIGURE 2

Concentrations of PYY3–36 (A), GLP-1 (C), and ghrelin (E) before (pre) and after (post) the study condition (Exercise compared with Rest) in younger adults and older adults. Panels (B), (D), and (F) show the change in PYY3–36 (B), GLP-1 (D), and ghrelin (F) from pre-to-post (isolated exercise effect) during Exercise relative to Rest in younger and older adults. Values are means ± SE of the mean. Differences in hormone concentrations between younger adults and older adults and between conditions (Exercise compared with Rest) at each time point were analyzed by analysis of variance. ∗Significant difference between younger and older adults during Exercise (P < 0.05). #Significant difference between younger and older adults during Rest (P < 0.05). †Significant difference in the pre-post change during Exercise relative to Rest between younger and older adults (P < 0.05). Exercise, exercise condition (60% $\dot{\mathrm{V}}$ O2peak) on a bicycle ergometer; GLP-1, glucagon-like peptide-1; PYY3–36, peptide tyrosine tyrosine 3–36; Rest, control condition (seated rest period).

FIGURE 3

Subjective perceptions of hunger (A), fullness (B), thirst (C), and nausea (D) before (pre) and after (post) the study condition (Exercise compared with Rest) in younger adults and older adults. Items were rated on a visual analog scale (VAS) from 0 (not at all) to 10 (very). Values are means ± SE of the mean. Differences in subjective ratings between younger adults and older adults and between conditions (Exercise compared with Rest) at each time point were analyzed by analysis of variance. ∗Significant difference between younger and older adults during Exercise (P < 0.05). #Significant difference between younger and older adults during Rest (P < 0.05). Exercise, exercise condition (60% $\dot{\mathrm{V}}$ O2peak) on a bicycle ergometer; Rest, control condition (seated rest period); SE, standard error.