Relationship between basal metabolic rate, thermogenic response to caffeine, and body weight loss following combined low calorie and exercise treatment in obese women.

To clarify whether there were any differences in basal metabolic rate (BMR) and thermogenic response to caffeine in individual obese women, and if so, whether such differences affected weight loss, the basal and resting metabolic rates at 30 min after a caffeine loading test (4 mg/kg ideal body weight, per os) were measured in 136 obese women and ten lean age-matched controls. The obese subjects were then asked to follow a combined low calorie diet and exercise regimen. There were no differences in the BMR and thermogenic responses to caffeine between the obese and lean groups. However, the BMR and the thermogenic responses to caffeine varied widely in obese subjects. After two months of treatment, body weight and percentage body fat in obese women were significantly (P < 0.001) reduced. There were significant correlations between the BMR and body weight loss (r = 0.3621, P < 0.001), between BMR/lean body mass and body weight loss (r = 0.3196, P < 0.001) and between the thermogenic response to caffeine and body weight loss (r = 0.6943, P < 0.001). When the criterion of a BMR less than 3.10 kJ/min (less than two standard deviations below the mean of the age-matched lean control) was used to define an obese group with reduced BMR, there were 30 obese subjects in this group, and their body weight was significantly decreased by treatment.(ABSTRACT TRUNCATED AT 250 WORDS)