Modpack version: Atomic Space 2.0.0a Release
Launcher: MultiMC

I went on a binge for the past hour eating as many new foods as I can, have had a full row of vanilla hearts the entire time even though I have leveled up several times.

This will be fixed in the next version, thanks for your report

So this is just visual? I don't much care about the armor bar, can I just disable that mod to get an accurate health bar?

I'm almost positive it's a visual thing but not 100 % sure

Yep it is visual and it is caused by overloader armor bar, it will be fixed in the next update