The human body has a lot of latitude and how it stores & taps it's reserves. You could eat less than than you expend & lose muscle mass instead of fat, for exam

The human body has a lot of latitude and how it stores & taps it's reserves. You could eat less than than you expend & lose muscle mass instead of fat, for example. So yes, humans are a thermodynamic system, but that isn't a model that explains the dynamics of what your body does with it's tissues. It's more complex than that. It's kind of like saying, "a CPU is just a resistive heater." There's a way in which this is true and it's a useful perspective for designing a cooling system. But it's a useless model to give to someone asking for advice in debugging race conditions, because you've erased the complexity their problems arise from. Additionally there's a moralizing component where people erase this complexity in order to blame people for their medical problems and frame it as an issue of irresponsibility. No one has ever said, "aircraft crashes are caused by gravity, and the moral failing of pilots not to understand this most basic principle. Imagine spending so much money on flight school when all you need to do is watch stuff fall, that's all you need to know." There is no gravity theory of airplane accidents in the same way there is a caloric imbalance theory of obesity. Consider also that airplanes are "simple"[1], well understood, engineered systems which are centrally coordinated, and that bodies are complex, evolved systems, containing autonomous components, many of which are very poorly understood. Aircraft are engineered for consistency, with faulty or expired components swapped out, whereas humans vary dramatically, not only between each other, but over the course of their lives. Other people have very different bodies & experiences than you do; it can be night and day. I came to understand this when speaking to a friend with executive dysfunction. I kept telling them they were beating themselves up or undermining themselves when they told me about limitations they experienced. Eventually they snapped at me and described their day to day in detail, and I realized their mind as a different place with different demons than mine, and that there were things I could do easily that they struggled with, and things I struggled with that were an ordeal for them. (They're a very smart and capable person who has abilities I do not, and of course I have demons and struggles they do not have as well.) I meant well but what I was doing was really undercutting and devaluing their lived experience, trying to comfort and bolster instead of understand. [1] In the sense that they are not "complex systems" https://en.wikipedia.org/wiki/Complex_system https://en.wikipedia.org/wiki/Complex_system (obviously aircraft are complex in a general sense)