Objectives
Metabolic rate is affected not solely by diet but also by environmental characteristics such as climate and seasonal changes
in day length. In the present study, we conducted a controlled study in which we observed metabolic response to short-term
energy restriction (ER).
Materials and Methods
Thirty-two subjects were divided randomly into a slight ER group and a moderate ER group. The energy intake per day for slight
ER vs moderate ER was 1462 kcal vs 1114 kcal. During the 4-day study periods, the same daily timetable, which consists of
nutrition, exercise, sleeping and others, was imposed on both groups. The same environment was also provided to both groups.
Results
After the 4-day ER, significant decreases in body weight and basal metabolic rate (BMR) were shown in both groups. The decrease
in body weight was 2% of the baseline level in both groups, and the decreases in the BMR were 6% of baseline levels in the
slight ER group and 13% in the moderate ER group. The decrease in BMR in the moderate ER group was significantly larger than
that in the slight ER group.
Conclusions
In a controlled study of short-term ER, we observed a significant decrease in BMR. There was a positive association between
the degree of ER and the reduction in BMR. Reductions in BMR were greater than those in body weight. It, thus, appears that
the minimization of weight loss is due to dramatic decreases in BMR. This suggests the existence of metabolic resistance against
ER.
Key words calorie restriction - controlled study - energy expenditure - human - nutrition