If someone with severe obesity loses about a third of their body weight, their knees experience nearly two times less pressure when walking — meaning their joints get a lot more relief than the weight they lost would suggest.

After people with severe obesity lose a lot of weight, they tend to walk faster and take longer steps, which means their knees don’t get as much relief as expected — the pressure only goes down by about a third instead of two-thirds, so the knee load drops about as much as the weight they lost.

When people with severe obesity lose a lot of weight, they start walking differently — taking longer steps and moving faster — and this might actually reduce some of the benefits that weight loss should have on their knees when walking every day.

If older adults with extra weight and knee arthritis lose 1 kilogram, their knees experience about 4 times less force with each step — which could really add up to less wear and tear over time.

If you're an older adult who doesn't move much and has extra weight plus knee arthritis, carrying more body weight means your knees get squished harder when you walk.

If older adults who are overweight or obese and have knee arthritis lose 1 kilogram of weight, their knees experience less strain when walking — about 1.4% less stress per kilo lost — which might help protect the inner part of the knee.