Effects of short-term exercise on appetite responses in unrestrained females

To examine the short-term effects of exercise and diet composition on appetite in unrestrained females.

A 2 x 2 repeated measures design study was conducted, with exercise and lunch type as the repeated factors.

The Human Appetite Research Unit at Leeds University Psychology department.

13 unrestrained, normal weight females were recruited from the student and staff population of Leeds University.

Subjects were assigned to four experimental treatments in a counterbalanced order. These were a control (no-exercise) session and an intense (70% VO2 max) exercise session followed by a free-selection test lunch consisting of high-fat/low-carbohydrate or low-fat/high-carbohydrate foods. The effects of exercise and lunch type were measured by monitoring energy intake and macronutrient intake during the test lunches only. Visual analogue scales were used to monitor profiles of motivation to eat during the treatments.

Subjects did not experience the marked suppression of hunger induced by exercise, which is a striking and robust finding in men. Moreover, unlike men, females rated a range of foods to be more palatable after exercise (F(1,12) = 8.0, P < 0.05). Similar to male subjects, exercise in females had no significant short-term effect on energy or macronutrient intake. Energy intake was significantly influenced by the fat:carbohydrate composition of the foods available (F(1,12) = 64.7, P < 0.001), and the short-term energy deficit induced by exercise when followed by low-fat lunch was completely wiped out when exercise was followed by a high-fat lunch (F(1,12) = 66.2, P < 0.001).

These results show that there are similarities and differences between males and females in the appetite response to foods varying in macronutrient composition following vigorous exercise. The differences may help to explain why exercise so often produces a disappointing effect on weight control in females.