Editorial Issue 357:

Question: Do Neopets regain HP when they eat?

TNT Answer: If you mean food, then no. They can be given healing potions, though, to regain their hit points.

Then someone wrote in to the editorial:
I am shocked, shocked that whoever writes the Editorial doesn't play the site. *tsks* Of course they regain some HP after they eat. I'm currently feeding my low HP Neopet (it got attacked in the Geraptiku tomb) some food and it just re-gained 43 HP. Also, Pteris regain it all after eating any food item with the word "worm" in it.

TNT Answer: Actually, those of us that are responsible for the Editorial play the site quite a bit! We've just always kept our Neopets in the Neolodge since our very early days, and therefore never realised feeding them restored HP! Thanks for catching that and writing about it to save us from having to make a note at the bottom of this Editorial about the correction. We actually found out the truth a couple of days after the Editorial went live. Imagine our embarrassment! :X