The morning OMAD produced the best results for me. Caveats: No alcohol and only whole foods, which is a minefield because many whole foods have been compromised with varietals that spike your blood sugar. I’m old enough to know how sweeter veggies are today. Corn, apples, and now the carrots are getting sweet. So growing/sourcing older varietals is important. I don’t think beans have been ruined yet like the grains, but with grains you can try ancient varietals on the market like einkorn.
I did keto, blue-zone, carnivore, 6/18 and then OMAD. From all this, my working hypothesis is that we evolved to have a slow release of carbohydrates in our gut, and when that runs out, we go into nutritional ketosis burning fats until the next bounty is found.