Smokers weigh less than nonsmokers, and typically gain 5-10 lbs. upon quitting smoking, yet the mechanisms by which nicotine influences body weight remain unclear. The chief aims of this research are to (1) characterize the short- and long-term metabolic and weight changes resulting from smoking cessation, (2) assess the effect of various levels of non-orosensory nicotine replacement on these effects, (3) test two specific models (regulatory vs. effector) of nicotine's role in human weight regulation, (4) determining the degree to which hypometabolism contributes to tobacco withdrawal syndrome severity, and (5) testing whether a restrained eating style places persons at risk for increased weight gain and withdrawal severity. 75 smokers will be randomly assigned to one of three groups (stratified on the basis of a restrained eating score): 44mg nicotine replacement, 22 mg nicotine replacement, or Placebo. Subjects will receive nicotine patch therapy for 6 weeks and intensive group counseling for 16 wks. Resting metabolic rate (RMR), thermic response to food, withdrawal ratings, 3 day dietary records, nicotine/cotinine levels, and activity will be assessed in an overnight (12 hr) calorimetry session prior to smoking cessation, and in 24 hr calorimetry sessions 1, 4, 8 & 16 wks post-cessation. If the 44 mg nicotine dose is sufficient to maintain pre-smoking cessation set-point, at 1 and 4 wks post-quit the 44 mg group should have a higher RMR and lower caloric intake than the other groups. The 22 mg group should weigh more than the 44 mg group by wk 16. Decline in RMR should be strongly associated with increased withdrawal severity, and those subjects with restrained eating styles should show the greatest increases in caloric intake, weight, and decline in RMR. In addition to providing a powerful test of two theories, this research also has great clinical significance. It may help to identify those smokers at greatest risk for weight gain, and suggest optimal strategies for managing weight gain related to smoking cessation. As fear of weight gain deters many smokers from attempting to quit, this information could provide significant health benefits.
