I just got back to the straight and narrow a week ago. I lost 10 lbs very quickly (2 days) but then I started exercising 1 hour- 1 1/2 hours a day and now have gained it all back. I didn't change anything else? Last time I did this I didn't exercise and lost a massive amount of weight, then used exercise to tone up. Does exercising make you gain that much weight? ( I know muscle weighs more than fat, but 10 lbs!??)