>>54847145Humans empower Pokemon with their presence. The most direct example of this, Ultra Necrozma, even winds the player despite Necrozma primarily gorging on the legend it's fused with and your Z-Ring.
Thus, we can assume the reason Pokehumans can eat giant sandwiches without issue is that the energy their body would have stored as fat is being yoinked by their Pokemon in between any actual exertion from normal activities, while the natural energy the Pokemon themselves give off keeps them from turning into corpses in response. This is also why someone like Melony who has like ten kids at the age of 58 is just "thicc" with crows feet, and why people talk about the health benefits of Pokemon doing random bullshit.
Source: my dog works at TPCi.