How losing weight can help with knee pain

How losing weight can help with knee pain

It is no secret that weight increases pressure on the knee joint. The knee is the largest joint in the body and is affected by extra load. As a person’s BMI increases, evidence shows that the pressure on their joints also increases, and this isn’t limited to the knee joint (1). This can lead to an earlier onset of osteoarthritis. This may not necessarily be due to the increased pressure, but rather the way overweight people may move differently, have reduced strength, functional limitations, and reduced healing effects, causing increased stress on the joint (2).

The knee bears 80% of your body weight when standing still and 150% more when you walk. That’s 264 pounds of force in an 80-kilo person. Overweight females are 4x more at risk of suffering from knee osteoarthritis (OA), and overweight males are 5x more likely (3). Being overweight is a clear factor for putting increased stress on the cartilage of the knee joint, leading to OA. Studies that have performed multiple X-rays over time have shown that people with a higher body weight are at increased risk of knee OA (4).

I know we are focusing on cartilage stress due to being overweight, but with the increased force on the knee, it will also cause the force to be controlled by other tissues, such as tendons and musculature. This can then lead to strains of muscles and tendinopathy. In patients with obesity, high levels of pro-inflammatory cytokines and high mechanical demand promote chronic low-grade inflammation (5). Obviously, there are many other tissues of the knee that can also become affected by increased weight, such as fat pads, bursae, and ligaments, so these are other complications of increased force through the joint.

Will losing weight have the reverse effects? A study suggests that it does, explaining that women with a baseline BMI of 25 or above, weight loss was significantly linked to reducing the risk of knee OA (6). For every 11 lb weight loss, the risk of knee OA dropped by more than 50%, which is a huge decrease in the risk factor for knee OA. If you’re overweight, experts suggest that losing 10% of your body weight helps. Research backs that up. In one study, people who lost at least 10% of their weight had more relief in pain and inflammation than people who lost less than that (7). Try to set a 10% goal if you are overweight; this is a great place to start and shows it can significantly help.

The key is to gradually and sustainably do this until the optimum weight is achieved. BMI is a common tool that measures a person’s weight in relation to their height. A BMI calculation provides a single number, which falls into the following categories:

• A BMI of less than 18.5 means a person is underweight.
• A BMI of between 18.5 and 24.9 is ideal.
• A BMI of between 25 and 29.9 is overweight.
• A BMI over 30 indicates obesity.

This can be found here: https://www.nhlbi.nih.gov/health/educational/lose_wt/BMI/bmi_tbl.pdf

1. Cicuttini FM, Baker JR, Spector TD: The association of obesity with osteoarthritis of the hand and knee in women: a twin study.
2. Tomlinson DJ, Erskine RM, Morse CI, Winwood K, Onambélé-Pearson G. The impact of obesity on skeletal muscle strength and structure through adolescence to old age. Biogerontology. 2016
3. Felson DT, Anderson JJ, Naimark A, Walker AM, Meenan RF: Obesity and knee osteoarthritis: The Framingham study. Ann.Int.Med. 1988;109:18-24.
4. Schouten JS, van den Ouweland FA, Valkenburg HA: A 12 year follow up study in the general population on prognostic factors of cartilage loss in osteoarthritis of the knee. Ann.Rheum.Dis. 1992;51:932-937.
5. Macchi M, Spezia M, Elli S, Schiaffini G, Chisari E. Obesity Increases the Risk of Tendinopathy, Tendon Tear and Rupture, and Postoperative Complications: A Systematic Review of Clinical Studies. Clin Orthop Relat Res. 2020 Aug;478(8):1839-1847.
6. Felson DT, Zhang Y, Hannan MT, et al: Risk factors for incident radiographic knee osteoarthritis in the elderly: the Framingham Study. Arthritis Rheum. 1997;40:728-733.
7. Intentional Weight Loss for Overweight and Obese Knee Osteoarthritis Patients: Is More Better? Messier SP, Resnik AE, Beavers DP, Mihalko SL, Miller GD, Nicklas BJ, DeVita P, Hunter DJ, Lyles MF, Eckstein F, Guermazi A, Loeser RF. Arthritis Care Res (Hoboken). 2018 Jun 18. doi: 10.1002/acr.23608.