Smoking, body weight, and CHD mortality in diverse populations

Background. It is well documented that smokers tend to be leaner than nonsmokers. It is also clearly established that smoking is detrimental to health. The question that immediately comes to mind, therefore, is whether the possible weight-controlling aspects of the smoking habit offset the harm induced by smoking. Methods. In this report, we present an analysis of 21 observational studies that examine the relationship between smoking status and BMI. With few exceptions, smokers are leaner than nonsmokers. Results. The average differences between smokers and nonsmokers are 0.97 kg/m2 for men (95% CI = 0.82–1.13) and 1.38 kg/m2 for women (95% CI = 1.19–1.58). However, considering the relationship of both BMI and smoking to coronary heart disease (CHD) mortality, adjusting for age, we find that 15.9 kg/m2 BMI units is required for men and 15.8 kg/m2 is required for women to offset the detrimental effect of smoking. This weight differential is 42 kg (93 lb) for a woman 163 cm (64 in.) tall. Conclusion. Our results demonstrate that the risk of CHD death among smokers is not reduced sufficiently by the lower BMIs to justify the habit. It is unquestionably better to quit smoking and gain weight than to continue to smoke.