Obesity is associated with an increased risk of cardiovascular disease (CVD) and other adverse health outcomes. In patients with pre-existing heart failure or coronary heart disease, obese individuals have a more favourable prognosis compared to individuals who are of normal weight. This paradoxical relationship between obesity and CVD has been termed the ‘obesity paradox’. This phenomenon has also been observed in patients with other cardiovascular conditions and diseases of the respiratory and renal systems. Taking into consideration the well-established relationship between osteoarthritis (OA) and CVD, emerging evidence shows that overweight and obese individuals undergoing total hip or knee replacement for OA have lower mortality risk compared with normal weight individuals, suggesting an obesity paradox. Factors proposed to explain the obesity paradox include the role of cardiorespiratory fitness (“fat but fit”), the increased amount of lean mass in obese people, additional adipose tissue serving as a metabolic reserve, biases such as reverse causation and confounding by smoking, and the co-existence of older age and specific comorbidities such as CVD. A wealth of evidence suggests that higher levels of fitness are accompanied by prolonged life expectancy across all levels of adiposity and that the increased mortality risk attributed to obesity can be attenuated with increased fitness. For patients about to have joint replacement, improving fitness levels through physical activities or exercises that are attractive and feasible, should be a priority if intentional weight loss is unlikely to be achieved.

肥胖与心血管疾病 (CVD) 和其他不良健康结果的风险增加有关。在患有心力衰竭或冠心病的患者中，与体重正常的人相比，肥胖者的预后更好。肥胖与心血管疾病之间的这种矛盾关系被称为“肥胖悖论”。在患有其他心血管疾病以及呼吸系统和肾脏系统疾病的患者中也观察到了这种现象。考虑到骨关节炎 (OA) 和 CVD 之间既定的关系，新出现的证据表明，与正常体重的个体相比，接受全髋关节或膝关节置换术治疗 OA 的超重和肥胖个体的死亡风险较低，这表明存在肥胖悖论。提出解释肥胖悖论的因素包括心肺健康（“肥胖但健康”）的作用、肥胖者瘦体重的增加、作为代谢储备的额外脂肪组织、诸如反向因果关系和吸烟混淆等偏见，以及老年和特定合并症（如心血管疾病）的共存。大量证据表明，较高的健康水平会伴随着各种肥胖水平的预期寿命的延长，并且随着健康水平的提高，肥胖导致的死亡风险增加可以减弱。对于即将进行关节置换的患者，如果不可能实现有意的减肥，则应优先考虑通过有吸引力且可行的体育活动或锻炼来提高健康水平。