Obesity, which is rapidly increasing worldwide, is a key factor in osteoarthritis due to mechanical overload of weight-bearing joints and systemic inflammation driven by pro-inflammatory mediators secreted by adipose tissue. This association has led to an increase in total hip and knee arthroplasties. Surgery significantly improves pain and function, but obese patients face higher risks of postoperative complications, especially in those with severe obesity, and often have poorer functional outcomes. Although preoperative weight loss is recommended, it is not consistently linked to reduced complications. A multidisciplinary approach focusing on nutritional status, weight stabilization, and rehabilitation is essential to optimize patient care.