Headaches when eating carbs?

Hello!

I do 3x 24h fasts a week (I’m on week 4). I have about 6-7 kg to lose so I’m expecting the fat loss to go slow, and I’ve started to get comments about my muscles are getting bigger and I definitely think it’s because of the increase in growth hormone from the fasts (I usually do resistance training at the end of my fast and break it with a protein shake)

On the weekends I try to be relaxed about what I eat while maintaining reasonable TRE. My question is— has anybody else noticed fatigue or headaches after eating more carb/sugar?

I had a large cookie yesterday after lunch and just felt terrible the whole day. I’ve also felt less than great the past few weekends— super tired and not particularly motivated to do much.

I don’t think it’s about fasting because I feel good during my fasts and during the week generally, which is when I try to be a little more controlled in my diet. Its occurred to me that it could be about sleep/circadian rhythm because my workday starts at 7 am so I go to bed at 10 and wake up at 6 during the week, but I stay up later on weekends.

I just thought I’d ask. If it is the sugar or the refined carbs, I don’t understand why my body is all of a sudden sensitive to them.