Appetite and Energy Intake Responses to Acute Energy Deficits in Females versus Males

Abstract

Purpose: To explore whether compensatory responses to acute energy deficits induced by exercise or diet differ by sex.

Methods: In experiment one, 12 healthy women completed three 9-h trials (control, exercise-induced (Ex-Def) and food restriction-induced energy deficit (Food-Def)) with identical energy deficits being imposed in the Ex-Def (90-min run, ∼70% of V˙O2max) and Food-Def trials. In experiment two, 10 men and 10 women completed two 7-h trials (control and exercise). Sixty minutes of running (∼70% of V˙O2max) was performed at the beginning of the exercise trial. The participants rested throughout the remainder of the exercise trial and during the control trial. Appetite ratings, plasma concentrations of gut hormones, and ad libitum energy intake were assessed during main trials.

Results: In experiment one, an energy deficit of approximately 3500 kJ induced via food restriction increased appetite and food intake. These changes corresponded with heightened concentrations of plasma acylated ghrelin and lower peptide YY3-36. None of these compensatory responses were apparent when an equivalent energy deficit was induced by exercise. In experiment two, appetite ratings and plasma acylated ghrelin concentrations were lower in exercise than in control, but energy intake did not differ between trials. The appetite, acylated ghrelin, and energy intake response to exercise did not differ between men and women.

Conclusions: Women exhibit compensatory appetite, gut hormone, and food intake responses to acute energy restriction but not in response to an acute bout of exercise. Additionally, men and women seem to exhibit similar acylated ghrelin and PYY3-36 responses to exercise-induced energy deficits. These findings advance understanding regarding the interaction between exercise and energy homeostasis in women.

FIGURE 1

Time-averaged appetite (A), circulating acylated ghrelin (B), and peptide YY_3–36 (C) AUC for each 9-h trial. *Food-Def significantly different from Ex-Def and control; †Ex-Def significantly different from Food-Def and control (experiment one: female participants only). Values are mean (SEM), n = 12 for appetite and n = 11 for acylated ghrelin and peptide YY_3–36..

FIGURE 2

Appetite (A), circulating acylated ghrelin (B), and peptide YY_3–36 (C) concentrations across the Con (▾), Ex-Def (•), and Food-Def (○) trials (experiment one: female participants only). Hatched shaded rectangles indicate standardized test meals, lightly shaded rectangle indicates exercise, black rectangle indicates ad libitum meal. Values are mean (SEM), n = 12 for appetite and n = 11 for acylated ghrelin and peptide YY_3–36.

FIGURE 3

A, Appetite ratings in Male Con (○), Male Ex (•), Female Con (▽), and Female Ex (▾) (experiment two: male and female participants). Hatched shaded rectangles indicate standardized test meal, lightly shaded rectangle indicates exercise, black rectangle indicates ad libitum meal. B, Time-averaged appetite AUC for each 7-h trial. ‡Males significant different than females. §Control significantly different than exercise. Values are mean (SEM). Females, n = 10; males, n = 10.

FIGURE 4

A, Plasma acylated ghrelin concentrations in Male Con (○), Male Ex (•), Female Con (▽), and Female Ex (▾) (experiment two: male and female participants). Hatched shaded rectangles indicate standardized test meal, lightly shaded rectangle indicates exercise, black rectangle indicates ad libitum meal. B, Time-averaged acylated ghrelin AUC for each 7-h trial. ¶Females significantly different than males. §Control significantly different than exercise. Values are mean (SEM). Females, n = 8; males, n = 8.