How much weight/inches is it possible to loose in 20 days with exercising and a strict diet?

2 lb/wk so 6 maybe: There is a difference between losing fat and losing water weight. And a rapid weight loss in a couple of weeks is often due to loss of fluid. A more reasonable goal is to lose 1 lb/wk over a longer period of time through a combination of healthy diet and exercise. See my guides on food and exercise. If health problems, get approval from your physician as appropriate. Thanks for asking! @drpam.