by Cassie Story, RD, Nutrition Subject Matter Expert
If you have heard that excess body weight can contribute to osteoarthritis, you may assume the reason is simple: more body weight puts more pressure on the joints.
That is part of the story, especially for weight-bearing joints such as the knees and hips. But researchers now understand that the relationship between obesity and osteoarthritis is more complex. Inflammation and other metabolic changes associated with obesity may also affect joint health, including joints that do not bear body weight.
What Is Osteoarthritis?
Osteoarthritis, or OA, is the most common type of arthritis. It develops as tissues within a joint change and break down over time. It can affect cartilage, bone, ligaments and other structures around the joint.
Common symptoms include pain, stiffness, swelling and reduced range of motion. OA frequently affects the knees, hips, hands, neck and lower back.
Importantly, the National Institute of Arthritis and Musculoskeletal and Skin Diseases notes that OA is not simply a result of “wear and tear.” Changes within joint tissues contribute to the disease, and several factors can increase risk, including aging, previous joint injury, genetics and obesity.
Body Weight Changes the Load on Your Joints
Every time you walk, your knees absorb forces greater than your body weight. Johns Hopkins Arthritis Center estimates that the force across the knee while walking can be approximately three to six times a person’s body weight. This means changes in body weight can significantly change the amount of force the knee experiences with each step.
Over time, greater mechanical loading may contribute to changes in cartilage and other structures within weight-bearing joints. But mechanical stress does not explain everything.
Inflammation Is Part of the Picture
Researchers have also found a relationship between obesity and osteoarthritis in joints such as the hands, which are not carrying body weight. That helped scientists recognize that biological factors must also be involved.
Adipose tissue, or body fat, is biologically active. It releases hormones and signaling proteins called adipokines that can influence inflammation throughout the body. Research suggests these inflammatory and metabolic signals may affect cartilage, bone and other joint tissues involved in osteoarthritis.
In other words, obesity-related osteoarthritis may involve a combination of mechanical stress and systemic inflammation, rather than pressure on the joints alone.
The Obesity Action Coalition’s Obesity and Osteoarthritis Fact Sheet also explains this connection and offers more information about how obesity may affect joint pain and OA risk.
Movement Still Matters When Your Joints Hurt
Joint pain can make physical activity difficult. Unfortunately, becoming less active can contribute to muscle weakness, which may place even more stress on affected joints.
That does not mean you need to push through significant pain. Activities can often be adapted. NIAMS recommends options such as walking, cycling, swimming, water aerobics and other low-impact activities as part of osteoarthritis management. Strengthening the muscles around a joint may also help support function and mobility.
Your healthcare provider or a physical therapist can help determine which types of movement are appropriate for your symptoms and physical abilities.
For a deeper explanation of how obesity, inflammation, muscle strength and movement interact with osteoarthritis, watch OAC’s Health Talk Understanding the Connection Between Obesity and Osteoarthritis with Kristine Godziuk, PhD.
Talk With Your Healthcare Provider
Osteoarthritis treatment is not one-size-fits-all. Depending on your symptoms and overall health, treatment may include physical activity, physical therapy, pain management, weight-management treatment, medications or other approaches.
If joint pain is affecting your movement or quality of life, it may be worth discussing both your joint health and your weight with your healthcare provider.
The Your Weight Matters Take the Challenge provides tools to help you prepare for that conversation, including questions to ask your healthcare provider and information about weight-management options.
Understanding why obesity and osteoarthritis are connected can help shift the conversation away from simply “putting less weight on your knees” and toward the bigger picture: supporting joint health, mobility and overall health in ways that work for you.
References:
Jamal, Naadir et al. Unravelling the ties that bind: The intersection of obesity, osteoarthritis, and inflammatory pathways with emphasis on glucagon-like peptide-1 agonists. Clinical obesity. 2025;15(1):e12700.
Nedunchezhiyan, U. et al. Obesity, inflammation, and immune system in osteoarthritis. Frontiers in Immunology. 2022;13:907750.
