Differences of energy expenditure and physical activity patterns in subjects with various degrees of obesity

An imbalance of energy intake and energy expenditure leads to obesity. However, little detailed information of energy expenditure and physical activity patterns in obese subjects is available. Therefore, we assessed total energy expenditure (TEE) with its components resting energy expenditure (REE) and activity thermogenesis (AT) and the patterns of physical activity in non-obese and in subjects with different degrees of obesity.

TEE and activity pattern were assessed with the SenseWear™ armband in 78 subjects (46 ± 12 years; 28 with normal weight/overweight, 13 each with obesity I° and II°, and 24 with obesity III°). In addition, REE was measured by indirect calorimetry and AT was calculated.

Although TEE (and REE) increased with increasing weight category from 2567 (1437) kcal/d in non-obese subjects to 3033 (1931) kcal/d in subjects with obesity III° (p=0.016, p<0.001, respectively) body weight adjusted TEE decreased from 33.1 to 22.1 kcal/kg/d (p<0.001). This was mainly due to decreased body weight adjusted AT (11.3-5.8 kcal/kg/d, p<0.001). AT consisted almost completely of non-exercise AT. In particular, for obese subjects exercise-related AT was negligible.

Higher degrees of obesity are associated with decreased body weight adjusted AT. These differences have to be considered for therapeutic strategies.