Obesity is one of the risk factors for hip or knee osteoarthritis (OA), since mechanical overload on weight-bearing joints activates chondrocytes and accelerates cartilage degeneration. Surprisingly, obesity and overweight also contribute to hand OA due to a systemic effect involving the pro-inflammatory and -degenerative role of some adipokines, secreted by adipose tissue, as well as some joint cells. Obesity-induced OA is now included in a larger phenotype termed "metabolic GA", since OA is associated with various parameters of the metabolic Ssyndrome (including type-2 diabetes) and excess cardiovascular mortality related to this disease. Early-onset OA should lead to suspect a potential metabolic syndrome. Weight loss strategies remain a valuable therapeutic approach to prevent OA and reduce its symptoms, and must be associated with physical activity to allow for optimal outcomes.