Objective: To stop smoking is commonly associated with significant weight gain, but the mechanisms for this are poorly understood. We assessed the effects of smoking cessation on body weight, insulin sensitivity, β-cell function, and appetite.
Subjects and methods: Twenty-seven long-term smokers (n=27; nine females/18 males, 28±1 years, 22.9±0.6 kg/m(2)) attending an ambulatory smoking cessation program in a community hospital in Vienna, Austria were examined at baseline (Visit A; still smoking) and after a minimum of 3 months of smoking abstinence (Visit B; n=14); relapsed smokers were not followed up. Participants underwent 3-h oral glucose tolerance tests and body composition measurements at each study visit. Fasting (QUICKI) and dynamic (oral glucose insulin sensitivity (OGIS)) insulin sensitivity and β-cell secretion (insulinogenic index 140 (IGI40)) were calculated. Food intake was quantified with a free choice buffet. Fasting plasma concentrations of neuropeptide-Y (NPY), peptide-YY (PYY), glucagon-like peptide 1 (GLP1), leptin, ghrelin, and visfatin were measured.
Results: AFTER 3 MONTHS' SMOKING ABSTINENCE, BODY WEIGHT, AND FAT MASS WERE INCREASED (+4 AND +22% RESPECTIVELY, P0.05) AND FASTING INSULIN SENSITIVITY DETERIORATED (QUICKI: post, 0.37±0.02 vs baseline, 0.41±0.2; P<0.05), while OGIS remained unchanged throughout. IGI40 increased by 31% after >3 months' smoking abstinence (P<0.01). Carbohydrate ingestion increased after stopping smoking (P<0.05). NPY fasting levels were increased after >3 months (P<0.05), PYY, GLP1, leptin, ghrelin, and visfatin were unchanged.
Conclusion: Smoking cessation is associated with transient metabolic changes including increased β-cell secretion in response to glucose and fasting insulin resistance. These alterations may be associated with or contribute to the body weight gain after smoking cessation.