[Tobacco and weight]

The weight increase which immediately follows the cessation of smoking is often dissuasive. All things being equal otherwise, the weight and adiposity of smokers are lower than those of non-smokers. The calorie intake of smokers is equal to that of non-smokers, but the nicotine absorbed with each cigarette smoked temporarily increases the basal metabolism and in particular the energy expended in all physical activities. The lack of compensatory increase of food intake in response to the increase of energy expenditure explains why smokers are underweight. Food consumption might be reduced by an increase of circulating fatty acids and by a nicotine-induced inhibition of insulin secretion. The weight increase observed after tobacco withdrawal is caused by the normalization of expenditures and by release of the brake on food consumption. Weight increase is usually important in heavy smokers, women and subjects with low physical activity. Fifty per cent of smokers who have given up smoking put on less than 3 kg. The effort required to mitigate this disadvantage is modest and it can be delayed and separated from the acute weaning period with a medicinal treatment.