Will losing weight help my knee pain?

Key points in 30 seconds

1. The force on your knees when you walk is several times your body weight.
2. So even a small drop in weight reduces the load by much more.
3. Walking more on a painful knee only tightens the loop.
4. Start with exercise that puts less weight on the knees, and build up the muscles.
5. If the knee is swollen and warm, or hurts even at night, other checks come first.

What we often hear

• "My knees hurt too much to exercise."
• "I'm told to lose weight, but it hurts too much to move."
• "If I lose weight, will my knees get better too?"

Will losing weight help my knee pain?

It helps. The force on your knees when you walk is several times your body weight, so even a small drop in weight reduces the load on your knees by much more.

Many people are stuck in a loop: their knees hurt so they can't exercise, they can't exercise so they gain weight, and the extra weight makes their knees hurt more. This loop has to be broken somewhere.

Where do I break it?

Start by moving in ways that put less load on the knees. Walking more on a painful knee only tightens the loop.

There are ways that put less body weight on the knees, such as walking in water, cycling, and strength exercises done sitting or lying down. Once the muscles around the knee start to support it, then you increase walking.

If you don't follow this order, you'll do it for a few days, hurt more, and stop. And once you stop, you're back where you started.

What about eating?

When movement is limited, eating plays a bigger role. But you need to cut back while keeping enough protein so you don't lose muscle.

The more your knees hurt, the more important it is to protect your muscle. When muscle is lost, there's nothing left to support the knee, and pain comes more easily. This is why losing weight by starving yourself is especially bad.

Do feet and posture matter too?

Yes. Even at the same weight, the direction of force on the knees differs from person to person. If your foot arches have collapsed or your legs are bowed, force concentrates on the inside of the knee.

So we don't look only at weight. We also need to look at which direction the force is going, so you can walk with less pain even at the same weight.

What are the limits of this assessment?

We don't have numbers on how much pain decreases when you lose a certain amount of weight. What we've written here is based on known mechanisms and what we've seen in the clinic.

One more note. If your knee is swollen and warm, if it suddenly gives way and you collapse, or if it hurts at night even when you're still, other causes need to be checked first. If cartilage damage is already advanced, the pain may not change much even if you lose weight.

We look at the knees and weight together. Losing weight reduces the force on the knees, but exercising for that is hard with knees that already hurt.

If your knees hurt too much to exercise, come see us. We'll start with what you can do while using your knees less.

How much losing weight changes things differs from person to person depending on the condition of the joint.