Whole-body calorimetry studies in adult men. 2. The interaction of exercise and over-feeding on the thermic effect of a meal.

Studies have claimed that an enhancement of the thermic effect of a meal (TEM) is an important adaptive mechanism to account for energy wastage during over-feeding. Eight healthy normal-weight young men were studied during 1 week on a weight-maintenance diet and again during 1 week when they were over-fed by 50% with fat. During each experimental week, the subject occupied a whole-body indirect calorimeter at 26 degrees for two separate periods of 36 h. The periods differed in the amount of exercise they contained. The thermic responses to the identical meals were measured during rest on one occasion and during exercise on a bicycle ergometer on the other. On the maintenance diet the absolute TEM (kJ/min) was 1.51 (SD 0.42) at rest and 1.31 (SD 0.75) during exercise (no significant difference). The equivalent values (kJ/min) on the over-feeding diet were 2.2 (SD 0.48) and 1.97 (SD 0.64) (no significant difference). The absence of a significant interaction between TEM and exercise was also demonstrated by the fact that the effect of over-feeding on total 24 h energy expenditure was unaffected by the subject's level of physical activity while in the calorimeter. In conclusion, the present study has provided no evidence to support the hypothesis that TEM is enhanced during exercise.