Potentiating effects of cigarette smoking and moderate exercise on the thermic effect of a meal.

The purposes of this study were: (i) to determine the relative thermic effects of smoking and exercise in fasted and postprandial states, and (ii) to determine whether there is a weight-controlling caloric advantage of moderate exercise in the postprandial state which might be used upon smoking cessation. The subjects were ten physically fit, young, male smokers. Twenty minutes of smoking (two cigarettes) while fasted resulted in a 6.0% (12.5 kcals/3h) increase in resting metabolic rate (RMR), and 20 minutes of walking (5.8 km/h) while fasted increased post-exercise RMR by 5.8% (11.7 kcals/3h). The thermic effect of a meal (TEM) (740 ml, 874 kcals) increased RMR 21.0% (42.3 kcals/3h), which was increased to 22.1% by smoking (45.0 kcals/3h). Exercise after a meal increased RMR 29.1% (58.1 kcals/3h). Post-prandial exercise potentiated the TEM, as the energy cost was 4.0 kcals/3h greater than the sum of the thermic effect of the meal plus the thermic effect of exercise in the fasted state. Postprandial exercise expended 112.2 kcals/20 min vs. 101.6 kcals/20 min for fasted exercise, a difference of 10.4%. The difference increased to 14.6% when the post-exercise thermic effect was included. It was concluded that the thermic effect of smoking and exercise were similar in the fasted state, but were substantially different postprandially. Moderate postprandial exercise appears to offer a substantial weight-controlling advantage when compared with fasted exercise.