Is it normal to be drained/need to eat again after only 3 hrs work?

I’ve worked in the service industry my whole life. Recently I began work as a server at a restaurant. We don’t get breaks. We can eat before or at the end of our shift. I’m usually eating a late lunch at 3-4, start my shift at 4-5. We get busy at 6-630. By 7-8 I’m feeling mentally taxed and I need to eat something or i literally can’t go on, my energy is low, I can’t think straight, etc. I checked my doc for hypoglycemia but im ok. This doesn’t happen at some of the other jobs I work, but in general what does it is demanding work wipes me out fast, especially mentally demanding, and I can’t last the usual 5-6 hours until my next meal. I literally have to drink pop or eat a small snack to go on.

This could be fine but I am concerned im gaining weight from it, plus I feel out of control and I don’t like it.

This happened before as a barista recently. I had been a barista years before that. Often I would have a second breakfast but other than that it wasn’t affecting my life/work situation bad. I just needed to eat, and taking a break helped.

I know serving is demanding work and of course im contemplating maybe it’s not for me, despite the money being good.
Im just wondering if there’s anything im missing.

Other jobs I’ve worked like in retail, delivering pizzas or management I was able to go the usual 6-7 hours before eating/taking a break.

But those were almost 10 years ago. I’m in my late 30s now.

Years ago I worked at a bar as well as a host, which was also demanding at times. Started my shifts at 5 or 6 and went until 1. Usually ate my dinner at like 8-10 or so, something quick, no break. But it wasn’t ever wiping me out like it is now. Years ago I used to work at a restaurant in the kitchen doing prep, it would get demanding at times but I never remember myself pulling away to snack because I couldn’t handle it. I usually lasted til almost the end of my shift (5-7 hrs later) when I ate.

Not sure what to do.