Increased intensity of a single exercise bout stimulates subsequent fat intake

Abstract

BACKGROUND: The physical activity pattern in society has in recent years changed from necessary occupational activity to voluntary activities during leisure-time. How this change in lifestyle affects the selection of dietary intakes is presently unknown.

OBJECTIVES: The aim of the present study was to investigate the different effects of high vs low-intensity exercise on the following day's dietary energy intake and macronutrient selection.

DESIGN: The study was designed as a controlled randomized cross-over study which compared food selection and energy intake the day following a low-intensity vs a high-intensity exercise bout. We included 32 healthy normal-weight subjects of four subgroups (young males, young females, old males and old females). On two different occasions they performed either 60 min low-intensity (30% of V˙O²_max) or 30 min high-intensity (60% of V˙O²_max) exercise during 24 h measurements of energy expenditure. The energy intake and macronutrient selection of the subsequent day was assessed by offering them an ad libitum buffet at breakfast and at lunch.

RESULTS: Following the low-intensity exercise the subjects chose a diet with an energy percentage from fat similar to that of their habitual diet—36.7% (95% CI: 34.3, 39.0) vs 35.6% (95% CI: 33.0, 38.2; NS). Following the high-intensity exercise they chose a diet with 39.9% (95% CI: 37.2, 42.6) fat, which was 3.2% (95% CI: 0.6, 5.9) higher than following the low-intensity exercise (P0.05) and 4.2% (95% CI: 1.1, 7.4) more than their habitual diet (P<0.01).

CONCLUSIONS: The present study shows that changing the type of activity of a single exercise bout from 30% of maximal aerobic capacity for 60 min to 60% for only 30 min resulted in consumption of a diet the following day with a higher fat energy percentage compared with the diet selected after the low-intensity exercise. However, the higher fat content diet did not result in a higher energy intake.