I have a toon who's been working hard. Energy 7026%.
He was just short of finishing his food event point bar, so I had him nibbling one each of every fruit I had on hand.
After half a dozen(?) fruit, nothing was added to food satiations. The FEP bar didn't fill. Cores were produced, if the fruit had one. Otherwise the food eaten disappeared normally. His satiety is at 0.0% and his food efficacy is at 300%
While I was typing this, the energy went down to 6978% but no other change. He is not injured. (This seems like an awfully fast decline. He hasn't been working.)
I have another toon who ate successfully a couple of RL hours ago. He was barely in the healing range of energy when fed, and ended up with his energy nearer full.
I'm using Ender's beta client, but in this case I wouldn't expect the client to matter.
But I'll check with the default client soonish.