The FastDay Forum

Is it possible to have too few calories on a fast day? I know 500 calories is the maximum but is there a minimum?
TIA

I don't think there is a minimum on a fast day. You just need to keep below the max.

However, for 5:2 (or 4:3) you do need to eat close to your TDEE onother days, to avoid going into starvation mode.

Hi and welcome:

No. Many on this site, including me, do not take in any calories on fast days.

My signature says it all.

Good Luck!