Effect of exercise on spontaneous calorie intake in obesity

The effect of increased physical activity on energy intake and balance was investigated in six obese women (mean 167% above ideal body weight) voluntarily hospitalized for metabolic balance studies. Three 19-day treatments-one sedentary and two with treadmill exercise which increased daily expenditure to 110% (mild) and 125% (moderate) of sedentary expenditure-were imposed on each subject. Individual daily expenditure and ad libitum intake were determined by activity diaries and covert monitoring, respectively. Subjects selected and did not not change an intake level which allowed for energy balance during the sedentary period only. Therefore, the difference between intake and expenditure between treatments was significantly different (sedentary 11, mild -114, and moderate -369 kcal/day). The negative balance observed with mild and moderate exercise was obtained because while expenditure was raised with exercise, no compensatory increase in intake occurred. Moderate, realistic levels of activity did not regulate intake.