Body fatness and smoking history predict the thermic effect of smoking in fasted men.

Epidemiological studies suggest that body composition and smoking history are related to degree of weight gain following smoking cessation. We hypothesized that body composition and smoking history affect the thermic effect of smoking (TES), which in turn would influence weight gain. Forty males ranging in age from 20 to 70 years smoked two cigarettes (0.8 mg nicotine yield) in 20 minutes, after which resting energy expenditure (REE) was measured during the next hour. The average change in REE (delta REE) was 4.97% (P < 0.0001), with a range of -2% to +14%. delta REE was greater than 1% in 35 subjects, less than 1% in three subjects, and reduced in two subjects. Body fatness was negatively correlated with delta REE (r = -0.68, r2 = 0.46). Multiple regression analysis indicated that body fatness (%) and pack-year history of smoking strongly predict delta REE (R = 0.82, R2 = 0.68; delta REE = 11.090-0.296 x %FAT-0.037 x pack-year). It was concluded that body fatness and smoking history substantially influence the thermic effect of smoking. In addition, this finding helps explain the wide range in TES which has been reported among subjects in many previous studies.