Does losing weight help knee arthritis?

What it is

Extra body weight adds load to the knee with every step. Losing weight, through a change in eating and more activity, reduces that load. This page covers adults with knee arthritis who are overweight.

What the research shows

A pooled analysis of 4 trials with 454 people found small improvements in pain and in physical function. The average weight loss was about 6 kg. Function improved most when people lost more than 5 percent of their body weight.

A large American trial, called IDEA, followed 454 overweight or obese adults aged 55 or older for 18 months. People who combined a diet with exercise lost about 10.6 kg on average, and had less pain and better function than people who changed their diet only, or exercised only. Nearly 4 in 10 of them had little or no pain at the end, compared with about 2 to 3 in 10 of the other two groups. The Australian GP guideline, the international OARSI guideline and the American College of Rheumatology all strongly recommend weight loss for people with knee arthritis who are overweight, usually aiming for at least 5 percent of body weight.

Risks and effort

The IDEA trial was supervised, and it found that a loss of 10 percent of body weight was possible and safe for these older adults. Losing weight is hard to keep up, and it takes effort over many months.

What usually works instead

Exercise has the best evidence on its own and works well alongside weight loss. See Does exercise work for knee arthritis? and Osteoarthritis of the Knee.

Questions people ask

How much weight do I need to lose?

The pooled analysis found that function improved when people lost more than 5 percent of their body weight. The IDEA trial aimed for 10 percent.

Is diet or exercise more important?

Together they did best in the IDEA trial. Diet alone and exercise alone gave similar pain relief.

Does this apply if I am not overweight?

These trials were in overweight people. The evidence does not tell us about people of a healthy weight.

Will weight loss repair the cartilage?

The trials measured pain and function, not cartilage repair.

Will my knee pain go away if I lose weight?

For many people it eases, though it may not go completely. In the IDEA trial, nearly 4 in 10 people who combined a diet with exercise had little or no pain after 18 months, compared with about 2 to 3 in 10 of those who changed their diet only or exercised only.

Sources

Select a source to read what the study or guideline found, in plain words, with a link to the original.

• 1Pooled analysis of weight loss trials, 2007Review
• 2IDEA trial of diet and exercise, 2013Trial
• 3RACGP guideline for knee and hip osteoarthritis, 2018Australian guideline
• 4OARSI guideline for knee and hip osteoarthritis, 2019International guideline
• 5American College of Rheumatology guideline, 2020US guideline

Last reviewed 24 October 2026. Next review due October 2028.