The Difference between the Basal Metabolic Rate and the Sleeping Metabolic Rate in Japanese

Previous studies have demonstrated the difference between the basal metabolic rate (BMR) and the sleeping metabolic rate (SMR) ; however, the difference in the Japanese population has not yet been explored. This study examined the relationship between the BMR and SMR in ninety-four healthy Japanese subjects (37 males and 57 females, 39±12 y of age and 22.0±7.4% body fat) in a respiratory chamber. The SMR was significantly lower than the BMR (1,416±245 vs. 1,492±256 kcal/d) ; however, there was a highly significant correlation between the two (r=0.867 : p<0.001). The ratio of SMR/BMR largely varied among individuals (0.95±0.08, 8.4% of the coefficient of variation). The ratio was significantly lower in males than in females (0.93±0.10 vs. 0.97±0.06, p<0.05). None of the anthropometric measures (age, weight, body mass index, body surface area or percent body fat) correlated with the ratio. These results showed that SMR was 95% of BMR on average in a healthy Japanese group. However, when applied over a longer time period (24 h or more), the difference tends to become negligible for most analyses in a group. Although the difference between SMR and BMR will induce a 5% gap of physical activity level defined as the total energy expenditure divided by the BMR or SMR, this factor seems to have little practical importance in epidemiological research.