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No evidence for a chronic effect of smoking on energy expenditure
P M Warwick1, H M Edmundson, E S Thomson
1Department of Biochemistry, Microbiology and Nutrition, University of New England, Armidale, NSW, Australia.
Objective:
To investigate whether effects of smoking on energy expenditure (EE) extend chronically beyond smoking the last cigarette.
Design:
Eight subjects (5M,3F) were studied over three consecutive months, after smoking as normal (S) on 1-3 occasions, and after not smoking for 4-8 weeks (NS) on 1-2 occasions. On each occasion subjects underwent one 32-h measurement of EE in a respiration chamber (8-h overnight plus a 24-h day, with no smoking in the chamber) and one measure of basal metabolic rate (BMR) on exit from the chamber. Statistical differences were determined using paired t-tests.
Results:
There were no differences between S and NS for any of the EE measures, either including (n = 8) or excluding (n = 5) three subjects whose urinary cotinine excretions suggested failure to stop smoking during NS. For S and NS (N = 5) respectively, overnight EEs during the first night in the respiration chamber were 2.08 +/- 0.38 and 2.10 +/- 0.42 MJ/8-h; 24-h EEs during 12-36 hours after the last cigarette were 8.38 +/- 1.6 and 8.24 +/- 1.34 MJ/day, and BMRs were 6.51 +/- 1.21 and 6.50 +/- 1.07 MJ/day.
Conclusion:
We found no evidence for a chronic effect of smoking on EE.