I'm not claiming that the body can somehow defy the laws of thermodynamics. Obviously to become "heavier" one must consume more energy than one expends, but to lose fat -- specifically fat, not muscle tissue or bone or water -- the question is this: how important is the role of hormones in fat regulation? Does an increased insulin load, coupled with insulin resistance caused by long-term exposure to chronically high insulin levels, promote greater fat storage? And does this greater mass of fat, which itself is a hormonally active organ, affect the body in a way that results in illness and further weight gain?
Would an endocrinologist tell a diabetic that macronutrient content doesn't matter? Should we give that same advice to people with metabolic syndrome or those who are at risk of developing it? If insulin resistance is the primary cause of Type 2 Diabetes, and insulin is the primary hormone involved in fat storage -- both non-controversial statements -- then wouldn't it make sense for those at risk of developing T2DM to eat foods that produced a minimal insulin response?
Read Taubes's thought experiment I linked above. If you're willing to make nutrition texts bedtime reading, then you will at least find it interesting, even if you disagree with it. Though Taubes is not a scientist and he doesn't claim to be, he does make a compelling argument.
> Don't pull out the "a simple failure of willpower" straw man; I never claimed that.
It wasn't intended to target you specifically, but this attitude is pervasive, even among medical professionals. There are people out there who would much rather believe that every obese patient is just a lazy glutton who can't control himself. I know a few of these people myself, one of whom is a prominent oncologist. Science requires that we put aside our biases and assumptions.
> Hormones play a HUGE role in metabolism. My bedtime reading is how the chemical reactions they drive fit into human metabolism. you're comment seems to make them out to be "magical", which I suspect is due to your ignorance of them.
I'm not claiming hormones are magical. I am merely suggesting that their known role in fat regulation might also play a critical role in obesity. It's been a while since I studied the topic in any great depth, so I can't compete with your bedtime reading, and I don't want to link spam, so I'm keeping it simple.
Anyway, I believe the science will eventually shed some light on this issue. There are clinical trials in the planning stages right now, so hopefully we won't have long to wait.