PurposeTo explore whether compensatory responses to acute energy deficits induced by exercise or diet differ by sex.MethodsIn 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.ResultsIn 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.ConclusionsWomen 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.

The purpose of this study was to examine the effect of oral contraceptive (OC) use on salivary secretory immunoglobulin A (SIgA) levels at rest and in response to an acute bout of moderate–vigorous exercise during 2 phases of the 4-week OC cycle corresponding to different phases of the synthetic menstrual cycle. Ten healthy active females completed a cycling at 70% peak oxygen uptake for 45 min at 2 time points of an OC cycle: during the equivalent in time to the mid-follicular phase (day 8 ± 2) and the mid-luteal phase (day 20 ± 2). Timed unstimulated saliva samples were obtained before, immediately postexercise, and 1 h postexercise and analyzed for salivary SIgA. Salivary SIgA secretion rate was 26% (95% confidence limits (CI) 6–46) lower at postexercise compared with pre-exercise during the synthetic follicular phase (p = 0.019) but no differences were observed during the synthetic luteal trial. Saliva flow rate was 11% (95% CI, 8–30) lower at postexercise compared with pre-exercise (main effect for time; p = 0.025). In conclusion, the pattern of salivary SIgA secretion rate response to moderate–vigorous exercise varies across the early and late phases of a monophasic OC cycle, with a transient reduction in salivary SIgA responses during the synthetic follicular phase. These findings indicate that monophasic OC use should be considered when assessing mucosal immune responses to acute exercise.