Overweight is defined as a 15 % excess body weight (BW) relative to ideal BW. This nutritional disorder could result from dysregulated metabolism orientation toward anabolism. The aim of the study was to investigate the endocrine profile of naturally-acquired obesity in cats. One hundred and ninety four client-owned cats (males= 2 intact and 80 castrated, females= 13 intact and 99 neutered; mean age = 6.8 ± 3.1 y; mean BW = 8.0 ± 1.0 kg) were enrolled. The overweight had been estimated (蠅15 % ideal BW) by veterinarians. Blood samples were collected before and 1h30 after IM tetracosactide injection used as stimulant of adrenal glands secretion. Plasma cortisol, insulin-like growth factor (IGF1), insulin, leptin and prolactin concentrations have been determined. ANOVA and Pearson's correlation analysis was performed to assess the effect of BW, gender and age on hormonal concentration. Plasma IGF1, leptin and prolactin concentrations were higher than the reference range in 60 %, 38 % and 51 % of the cats, respectively. According to insulin and glycemia values, 23 % of cats were insulin resistant and 2 % diabetic. The BW, IGF1 and insulin concentration was significantly higher in male than in female cats. The BW and insulin concentration significantly changed with age. The BW was positively correlated with plasma IGF1, leptin and insulin concentrations. The results show that overweight in cats is an endocrinopathy. These hormonal disorders could increase the risk of pathological conditions onset and also shorten life span. Management of feline obesity should then include an endocrine evaluation that could be useful for the prescription of nutritional and medical treatment.