This art was originally done by  xchiseaxmargaritax and you can view and favourite the original artist's upload here: https://www.furaffinity.net/view/28079124/

This picture here illustrates Kinchaku's, relatively speaking, dangerous state. Pouched Tree Spirits, like him, usually tend to keep a very high-maintenance diet, due to their larger bodies and heftier weights. This does come with a downside, of sorts. Should they neglect to eat or keep to their usual eating schedule and pass a threshold of hunger, they change into a different, more 'mindless' state. Their eyes dilate and grow to the size of dinner plates, their cheekfur loses definition and becomes poofier and/or messier, their stomach starts growling and gurgling non-stop and their mental capacity breaks down, focused on one thing: Their hunger.
In this state of hunger, Kinchaku will seek something, anything to fill his belly. First, however, they will always seek out another Tree Spirit to swallow up. Not as food, but merely as 'belly filler', to assist with the impending food binge. Focused solely on their hunger, they lose all logical capcity, falling into a 'feral' sort of mindset, hunting down any Tree Spirit he can find. One tactic he likes to use is to stand right in front of a Tree Spirit and proceed to roar in their face, stunning them while moving his maw closer, so he can shut it around them and get to trying to swallow them.
The Tree Spirit that is swallowed, however, does not suffer a fatal fate. Rather, instead, once deposited in the belly, they end up in a bath of a special fluid, watery at first but slowly thickening overtime through the agitation/splashing/kneading/rubbing/etc into a thick goo, which eventually cocoons over the Tree Spirit, preserving them. After a period of time has passed (This can range from a day, to a week or two, to a whole month), they're passed through, released from the belly and allowed to 'hatch', leaving with little more than a few extra pounds for a few weeks.
While the process is perfectly safe and harmless, Tree Spirits would rather run than stay and get swallowed up. The most common reason is mainly due to the time they may be contained for. They'd rather be doing other stuff than end up trapped in a belly for a while. Rarely, though, some will admit that they're a little bit afraid at how Pouched Tree Spirits act in their hunger states.

That said, there is a way to halt the state before anyone gets eaten. By feeding the afflicted Pouched Tree Spirit, one can simply feed them until they are full enough, that the state ends up cancelling itself out, causing them to revert to their prior, normal state. Granted, this must be done before another Tree Spirit gets eaten, otherwise doing so afterwards would be more or less 'following the normal path'.
Their appetite in this state is also specific. When hunting for the belly filler, they will only accept another Tree Spirit as their belly filler. Anyone else is either ignored, passed aside, or set aside gently. Basically, if you're not a Tree Spirit, you're perfectly safe.

Take one guess as to whom the unlucky victim in the pic is~ :3