Going from 16 hours of fasting to 23 is a huge jump. I think you need to take time to transition to OMAD. Try 18 hours then 20. I also don’t really think it’s that common for anyone to literally have a 1 hour eating window. That’s really too short to eat enough without stuffing your face. You can technically do OMAD over 2-3 hours.
I am fairly new to the omad diet. I started with eating from 12-8pm for about a week and a half then switched to omad. The first day I felt a little tired and a little dizzy. However, I have not felt that way since then. I eat a fairly huge meal with chicken, broccoli, and others. I always try to drink a lot of water. I would suggest eating a big meal while on omad.
If you are going to do OMAD every single day, you still need to make sure you are meeting your nutrition requirements in that meal. Yes, there is calorie restriction involved, but it’s not meant to be like 16:8 is 1,800 calories but OMAD is only 600 calories because you’re only eating “dinner”.
What you are doing is compressing your daily caloric and nutritional needs into a single meal. There’s a floor you should not go below for OMAD because it can lead to malnutrition and illness.
And if you are not able to do that, then you have to expand your eating window and/or eat more than one meal.
For example, it’s challenging for adults to meet all their micro and macro needs below 1200 calories without external supplementation.
I agree with Excellent_shopper - work your way up from 16:8, and if you don’t feel well, don’t be a hero. Listen to your body and break your fast if you don’t feel well. Keep up with your hydration needs through the day.
I do a 4 hour window once a week, and an 8 hour window every two weeks, whenever my body says to. Some days I can just tell I won’t feel good if I wait 8 more hours to eat, and there’s no reason to suffer all day.
Are you also doing low carb? Although, eating OMAD limits your carbs along with other macros so almost by definition you are low carb.
Kinda sounds like “keto flu”, which is really an electrolyte deficiency. From what I have read the best way to treat keto flu is to up your salt intake to about 4 grams per day.
I only had one day doing OMAD where I felt bad. I drank a beef broth with salt and instantly felt great. That was my only bump. Right now I just overate on pizza cuz I’m vacationing. So tomorrow I will fast longer than 24 hours maybe 27 if I can. Update: I’m at 39 hours I plan to eat at 6pm tonight