Mid 30s, When I started going to ~one meal a day (dinner), my sleep was better and I didn’t have the afternoon digestive tiredness.

I only have coffee for breakfast (black, dairy doesn’t feel great to me first thing), keep hydrated, if I eat a huge dinner (large salad,carbs,protein,fruit) it’s amazing how it lasts 24 hrs.

I do not go to the gym though (not sure if my eating habits would be compatible with being a gym goer, I do walk a few miles a day though).