The short version seems to be that xenochemical effects, with varying genetic sensitivities, cause excessive appetite in animals via similar pathways to humans.

The short version seems to be that xenochemical effects, with varying genetic sensitivities, cause excessive appetite in animals via similar pathways to humans. In particular, food contaminants like antibiotics, emulsifiers, and plastic monomers (bisphenol A) may disrupt gut bacteria thus affecting hunger. The behavior of these animals is used as an example to argue that this hunger is very difficult to ignore. The effect of emulsifiers on gut bacteria seems particularly worthy of investigation because, unlike antibiotics and plasticizers, emulsifiers are added to foods intentionally. It seems likely that because all of these xenochemical effects are purportedly mediated via effects on the gut ecosystem, they can probably be mitigated or even eliminated by a diet which promotes the health of gut bacteria; presumably, one with plenty of fiber and fresh vegetables. The bit about wild animals getting fat links to a paper about marmots which blames it on climate change extending the growing (non-hibernation) season. Seems to be unrelated IMHO.