The FastDay Forum

I was starting to get really discouraged last week - I've been on 5:2 for six weeks, and after losing 2lb in the first two weeks, my weight loss just stalled.

However, over the weeks, my appetite has really decreased - and on Friday, after several feed days in a row where I'd felt ridiculously uncomfortably full after eating my 2000 calories, I decided that my TDEE must in fact be a bit lower than that. I switched to around 1600 for Saturday and Sunday, which felt much more comfortable - and lo and behold, when I weighed this morning I'd lost 1lb.

However, when I decided to do a bit more research about my TDEE, all the TDEE calculators I used estimated my TDEE as around 2000 calories, which is what I'd been eating on feed days anyway (and not losing weight). I'm not sure why this is - perhaps it's because I'm SO sedentary (I work from home so walking from bed to desk in the morning and back again at night is about the sum total of my exercise) that it throws the calculators off?

I suppose what I'm getting at is - how important is it to stick to your recommended TDEE on feed days? Is it okay to eat quite a bit less than that if it's more comfortable, or does that risk messing up your metabolism?

[carorees]

Hi sparklecloud

The TDEE calculators are only a rough guide. There are a lot of assumptions about you made in the formulas used, such as how much muscle you have, how much fat, what 'sedentary' vs 'light exercise' actually means, etc. If you found you were not losing on 2000cal/day on feed days but you are on 1600 then probably 1600 is right for you. I'd carry on with what feels comfortable and see how it goes. I think that if you undereat you may slow your metabolism slightly but what that means is that to lose weight you have to undereat by even more and then that means you are on a calorie restricted diet just like all the others! So, I think it is best to try to work out approx what your TDEE might be and go from there. This is what you have just done. If you are not feeling hungry on feed days but comfortable then I'm sure you are not undereating. As you lose weight your TDEE will also decrease (you are having to move less weight around) so you may have to rethink again after a while.

If you eat x calories/day average for a month and don't gain or lose then you've found your TDEE - it's x

[carorees]

So, in fact you could work out your average daily intake for the previous 4 weeks (i.e., counting the cals on fast days) and that would be your new feed day allowance! Which, if you have been eating 2000 on feed days and 500 on fast days is just a bit below the 1600 you have settled on! Case solved!

Thanks for the help guys - I'll stick with 1600 on feed days then (and go down to 400 on fast days, which hopefully shouldn't feel too horribly difficult!)

I reduced my fast days to 400 after having lost weight since I started.
I was amazed at how much food you can have for 400 calories.
I'm sure you won't miss the 100 calories.
There are lots of filling recipes for 400 cals. You'll be spoiled for choice.
Good luck.