Losing weight can definitely improve most arthritic conditions, especially the common osteo-arthritis. Think of the benefit to someone who has arthritic pain in their weight-bearing joints like their knees and hips. When you walk around with an extra 10, 20 or 50 lb, your joints will feel every step you take, so any loss of weight will mean an improvement. When you lose weight properly, even the small joints in your hands become less inflamed and less swollen, resulting in diminished pain and greater movement from issues such as rheumatoid arthritis.