A study involved over 150 obese individuals with knee OA where they were put on a 4 month special weight loss diet.
After 4 months, the average weight loss was 14kg (30lbs) which resulted in 7% reduction in knee joint compression forces during gait. They calculated that for every 1 kg in weight loss, the peak knee load was reduced by 2.2 kg. I think that is an amazing fact to tell a patient.
Each pound of weight loss reduces the pressure on the knees by 2lbs when walking!
The great thing is that once the weight was lost, still after one year the benefits in reduced knee pain were maintained even if they did not stick to their diet or a knee exercise program. Therefore, weight loss is beneficial in the short and long-term even if they slack off in their diet and exercise.