That being said, I'm not just talking about discrete simulations (as Wolfram has made particularly interesting finds in cellular automata), I'm talking about real world root cause failures in complex, integrated, man/logic/machine settings (which, do include a biological component of sorts). You cannot hope to find the truth in an analysis of a real-world system (again, not just some pre-programmed simulation, real computers doing real work with real people), without falsifiability.
I agree, but that doesn't mean the system is designed to be easily analyzed via falisifiability. I think a pretty common scenario goes something like this
Researcher: I have a great simple falsifiable hypothesis!
Other person: Awesome! What does it mean if it's true!
Researcher: Uhhh, well I got a list of things that might be happening if it's true.
Other person: Um ok, well you must have a pretty good idea if it's false then?
Researcher: Oh yeah! I got another list!
Other person: .... a lot of the items are the same.
Researcher: Yeah, sorry about that
Certainly hunger would be a complex one, but even in a complex system, you have first, second, third, etc order effects. Furthermore, as you noted, biology generally leads to extremely robust systems, and a system that ignored muscle starvation due to visual stimulation is distinctly *not* robust. The muscle cells can be considered as intelligent actors, just as intelligent as any bit of brain tissue, and they simply cannot be considered a lower order term.
And so in the end, I think you're making the same mistake you're pointing out here - you're treating a large, complex system, as dictated to by a single organ as a first order effect (i.e., it's all in your brain). In fact, biology is *filled* with intelligence, even down to the cellular level, and a robust system simply wouldn't make "tastiness" it's primary directive - that's not robust by any means. It *is* rational to think that cellular intelligence would be concerned with things like protecting from toxic levels of glucose in tissues and the blood stream, and sufficient energy to survive, and the complex failure of the system to maintain a healthy weight (in order to survive in the short term), is quite neatly explained by the insulin and differential insulin resistance mechanism as a *first order* term.
Hunger is a neurological effect so it (probably) all has to end up in the brain at some point, but we don't know the precise inputs, some is undoubtedly largely determined by signals from the body, muscle cells are probably sending some of those signals, but the brain is undoubtedly doing a ton on its own as evidenced by the huge role visual stimuli, social setting, and expectation plays on appetite.
That's why I'm very leery of anyone who stands up and says "I solved the obesity epidemic and it's due to X!" just because we know of so many contributing factors that go in and the number of variables we're changing.