Obesity is among the leading risk factors for the development of osteoarthritis (OA). Obesity leads to chronic pain, joint damage, decreased mobility, muscle atrophy, poor balance and eventually physical disability. It was found in a study that weight loss in patients with OA may improve their OA symptoms. The Framingham OA study demonstrated that a 5 kg loss decreases the risk for developing OA my more than 50% in women with BMI > 25. Bariatric surgery helps in gradual weight loss in obese people by about 60-70%, hence is considered a boon.
Source: Rishi L, Bhandari M, Kumar R. Can bariatric surgery delay the need for knee replacement in morbidly obese osteoarthritis patients. Journal of minimal access surgery. 2018 Jan;14(1):13.