I've been 4:3-ing for two weeks now, so 6 fast days. On the non-fast days I'm sticking to around 1,200 cals. On fast days I'm at 500. I weighed myself the day after my first fast and had lost a pound. Then I decided not to weigh myself until I had completed the next week, i.e. today. I am devastated to find I've gained 2lb! I've kept a food diary and double checked my calorie intake for the weeks to check I'm not overeating on non-fast days, I've drunk lots of water, I've kept my exercise level constant, post-menopause so no hormonal fluctuations. What am I doing wrong?