['Telomere shortening is physiologically associated with ageing but it may be influenced by oxidative stress and chronic inflammation, linked to obesity. Thus, obesity might represent an additional cause of telomere attrition. We aim to study relative telomere length (RTL) in obese subjects with and without metabolic syndrome and to assess the effect of weight loss induced by bariatric surgery.', 'We evaluated RTL in 107 obese subjects (62 with metabolic syndrome and 45 without metabolic syndrome), compared to 130 age-matched non-obese subjects. We also measured RTL in a subgroup of 93 obese patients prior to and 3, 6, 9 and 12 months after surgery.', 'RTL of obese subjects was significantly shorter (p<0.0001) than non-obese subjects but without differences between patients with and without metabolic syndrome (p=0.19). RTL was significantly shorter than baseline at 3, 6, 9 and 12 months after bariatric surgery.'] Does weight loss associated with bariatric surgery restore short telomere length of severe obese patients after 1 year?