The FastDay Forum

I just started 5:2 on Thursday and did the recommended 500 calories for women on my first fast day. It was not too difficult.

But I am wondering, what if your starting weight/BMI etc are way above average? I used the calculating tools, and it says my TDEE would calculate my fast day calories a bit higher than the recommended average of 500 for women. Should be about 580 (ya Im fat )

So, my questions is should I adjust my fast days, or just stay at the recommended 500 for those days?

Thanks for any guidance here
Diane

Like everything else it is a matter of choice. Some people( not me)go for zero calories. Some eat up to the allowance. Some go slightly over(often me). Some go for 500 . Sorry not very helpful but really the joy of this way of eating is flexibility and personal preference.

Hi and welcome:

Maybe this will help you decide:
viewtopic.php?f=6&t=6600

Thanks Merlin, sounds like balanced advice.

Simcoeluv, thanks for the link, I actually did read that earlier. I guess I'll just stay around the 500 mark and see how it goes. I recently lost 30 pounds, due to treatment for an illness. My first real goal is simply to not gain that back, so even losing slowly is better than gaining.

I'm right at 450 calories now for my 2nd fast day, and have an apple for later that will end my day just over 500.

The 25% of TDEE for fast day intake was an arbitrary choice, or perhaps a good guess at what would work. As far as I know, no study has been done testing different percentages (including 0) in the context of 5:2. I stick to 500 or less, but my TDEE is lower than 2000.

Most people experiment at the beginning to see what works and what they're comfortable with. Good luck!

I too have a lot to lose. My recommended fast day allowance was getting close to 600 when I started, but its now down to just over 500.

So Julie, when you started did you do your fast days at our best the 600 then as you lost, decreased it to the 500?

You have lost about 28 pounds, that's great. Are you pretty comfortable with the plan by now?

Different early smattering of papers looked at 25% to 40% of TDEE. MM settled on 25% and chose the 500/600 numbers based on a "typical" 2000/24000 cal TDEE for each gender.

IMO you should just consider the 500 a typical value not specific to YOU. This starting value should be replaced by what you get from your TDEE calculation, which considers your specific information (height, weight, age, activity). I agree with simcoeluv (in the link) that if you want to tweak it down you might underestimate your activity level by one.

So I would use your 580 number. TBH I wouldn't bother pushing much farther because as you lose weight your TDEE will fall and soon enough you will be closing in on 500 cal on fasting days, so enjoy the extra smidge now. Using 500 would be 21.5% for you.

FWIW, if you fast 2x a week, it would take almost 6 months for those 80 calories to amount to just one pound.