Sarahg wrote: Simcoeluv,my TDEE is 1500 so does that mean I eat less than that on non fast days?
And how many calories on fast days?
I am trying to be patient
Your TDEE is very low and explains your slow weight loss.
If you eat an average of 1500 (your TDEE) on your non fast days, and 500 on your fast days, you will be cutting out 2000 cal. per week from your diet. As a pound has around 3500 cal., that means you will be losing around one pound every two weeks. Even if you go to 25% of your TDEE for fast days (375 cal.), you only cut an additional 250 cal. out per week - that is only an additional 4 oz.
You are dealing with such small numbers that even eating nothing at all on your fast days would result in less than a 14 oz. loss for a week (3000/3500 * 16 oz. = 13.7 oz.)
Layer in water retention and you can see why you are losing so slowly, or gaining sometimes.
It works the same with any other 'diet'. My point is weight loss is never a fast process, and it is even slower when you are a small person and have little to lose.
Just eat on average your TDEE for your feast days, and 500 (or 375 if you want) for your fast days. You will lose the weight, so don't worry about that, but it will take time. Patience is the key.
(PS. The numbers also explain why you might easily regain lost weight. Just an extra hamburger a week could have you regaining a pound every 2 months. That is why 5:2 is so helpful there - you know how to cut calories out of your diet, even if you don't know where they came from in the first place.)