I tried it pre cancer as I was going overseas and wanted to lose a little. I lost 4 kgs over 6 weeks , which was about what I wanted. You do get hungry on the fast days but I used to do on the days I worked, spread it over 3 meals (some people use it up in 1 meal sitting) fill up with herbal teas and go to bed early! Don't do it 2 days in a row and DON'T make up for it on the other days,still eat sensibly.There are a heap of suggestions on Dr Google on how to make up the 500 calories, (obviously not cakes , chocolates etc :D ) you'd be surprised! Good luck with it all and keep your eye on the prize x