How much weight loss is needed to reduce knee pain?

How does body weight affect the knee?

The knee bears several times body weight during walking, climbing stairs and rising from a chair. Excess weight increases the load on cartilage and bone and is a major risk factor for developing and worsening knee osteoarthritis.

A study of 142 older adults with overweight or obesity and knee osteoarthritis found that each unit of weight lost was associated with about a fourfold reduction in knee joint forces per step during walking 2. Over thousands of steps a day, this reduction is substantial.

How much weight loss makes a difference?

A systematic review and meta-analysis of four randomised trials with 454 patients found that an average weight reduction of 6.1 kilograms was associated with small improvements in pain and physical disability. Meta-regression showed that disability improved significantly when weight was reduced by more than 5.1 per cent 1.

The authors suggested aiming for weight loss of more than 5 per cent within about 20 weeks, a rate of about 0.25 per cent per week 1.

Does more weight loss help more?

In the IDEA trial, 454 older adults with overweight or obesity and knee osteoarthritis followed intensive diet plus exercise, diet alone or exercise alone for 18 months. The diet plus exercise group lost 11.4 per cent of body weight on average, the diet group 9.5 per cent and the exercise group 2.0 per cent 3.

Participants in the diet plus exercise group had less pain and better function than the other groups, and knee compressive forces were lower in participants who lost weight through diet 3. This suggests that larger weight loss combined with exercise gives greater benefit.

What is a realistic way to lose weight?

Gradual weight loss through a sustainable eating pattern that reduces calorie intake, with plenty of vegetables, fruit, whole grains, lean proteins and fewer sugary drinks and processed foods, is more likely to last than extreme diets.

Support from a dietitian, structured programmes and regular monitoring increase success. For some people, medicines or bariatric surgery may be discussed with a doctor.

Why is exercise still important?

Exercise strengthens the muscles that support the knee, improves function and helps maintain weight loss. It also preserves muscle mass, which can be lost during dieting.

Low-impact activities such as cycling, swimming and water exercise, together with strength training, are well suited to people with knee pain.

Can weight loss prevent knee replacement?

Weight loss can reduce pain and improve function, which may delay the need for surgery for some people. It also reduces risks associated with surgery if a knee replacement is needed.

Even if knee replacement is planned, weight management and exercise before surgery can support recovery.

How can weight loss be maintained over time?

Keeping weight off is often harder than losing it. Regular physical activity, planned meals, regular weighing, managing stress and sleep, and continued contact with a support programme or healthcare professional help people maintain weight loss.

Some regain is common. Treating it as a signal to review habits, rather than a failure, supports long-term success. Maintaining strength training also helps protect muscles and joints as weight changes.

When should knee pain be assessed?

Seek assessment for a hot, swollen knee, knee pain after an injury, locking, giving way, or pain that disturbs sleep despite treatment.

Unexplained weight loss, or weight gain with swelling of the legs or breathlessness, should also be reviewed by a doctor.

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