BACKGROUND: Weight gain following cessation is a frequent reasonargued by smokers to continue to smoke or to relapse. Some metabolic parameters might mediate or modulate weight gain. Our objective was to explore the evolution of three metabolic parameters such as leptin, insulin and glucose among sedentary adults smokers who participated to a randomized controlled trial assessing moderate-intensity physical activity (PA) as an aid for smoking cessation. Whereas the primary outcome, i.e. continuous smoking abstinence, was similar in both groups at one-year follow-up, we performed secondary analyses to estimate impact of smoking and quitting on adipose tissue metabolism in smokers.