The effect of cigarette smoking on the thermic response to feeding.

Resting energy expenditures, the thermic responses to a standard meal (2.09 MJ 'Ensure') and energy intakes were measured in eight age/weight matched pairs of female smokers and non-smokers. The mean thermic response to the standard meal (including the thermic effects of smoking) was 35 percent greater for the smokers when compared with the mean thermic response to the standard meal alone shown by the non-smoker controls (P less than 0.05). There was a tendency for the smokers' energy intakes and resting metabolic rates to be higher then those of the non-smokers (5 percent and 9 percent respectively), but neither of these differences achieved statistical significance. Eleven smokers (three male and eight female) were studied after a 7-day period of abstention from smoking. Total energy expenditure following the meal did not change and the absence of a significant fall in metabolic rate (i.e. to the level of non-smokers) was thought to be partly a consequence of concomitantly increased energy intakes observed (11 percent, P less than 0.05) during this abstention period. Cigarette smoking and feeding appear to have additive rather than synergistic thermogenic effects on metabolic rate.