I think you missed my point, or I threw it by you poorly. I don't think they "should", I think they sometimes can. I sometimes can, and though I know from LW that not all minds are alike, it's safe to assume I'm also not wholly unique in my depression.

I agree that they sometimes can. I also agree people can sometimes lose weight. As far as I was concerned, our disagreement here (if one exists) isn't about whether it's possible in some cases.

Are you willing to agree to a statement like:

"Weight loss is possible in some cases, and in fact very easy in some cases. In other cases it is very hard, bordering in impossible given the marathon-analogy definition of impossible below. This can be negated by heroic measures like locking them in a room where excess food is unavailable and ignoring their appetite and distress, but in the real world you cannot do this. Because of these difficult cases, it is useful to explore the science behind weight loss and come up with more effective strategies.

If so, we agree, but then I'm confused why you were criticizing the Less Wrongers in your original statement. If you don't agree, please let me know which part we disagree about.

To your analogy of the marathon: There is a right answer to whether you can run X miles in Y minutes and not physically injure yourself. I'd imagine the majority of people never come close to knowing that answer because they do not posses the ability to refrain from rationalizing themselves out of the optimal result as discomfort begins during their run. I'm aware that I'm personally really bad at this—my first .5 mile I'm telling myself I'm Usain Bolt; by mile 2 I'm coming up with manifold reasons to stop pushing. No doubt some are good and rational reasons, but others are bullshit that I need only train my mind to recognize as such in order to push through and be successful.

If we are debating the extremely academic point of whether someone with your muscular structure can complete a marathon in X hours, okay. But suppose we find that of a thousand people who in theory are anatomically capable of completing the marathon, zero actually finish the marathon, due to discomfort. If our goal is to get them to successfully complete marathons, what percent of our resources do you think should be invested in proving they are physically capable of doing so right now and exhorting them to do this, versus coming up with things like training schedules and better diets and better shoes that will make it easier for them?

I felt like your original point was a complaint that we are trying the equivalent of coming up with training schedules rather than the equivalent of telling people they should be able to just keep going 26.2 miles unless their legs collapse, whereas I think this is probably a better strategy. Am I interpreting your complaint correctly, and do you disagree that the former strategy is better?

Can you instead imagine a scenario where a controlled calorie deficit was administered to a person where they received a balanced diet with all the nutrients they needed? 300 kcal was arbitrary. Pick any number. Isn't there some number that would be negligible in terms of the utility of its nutritional value and yet provide a calories deficient sufficient to lead to weight loss?

I think we're definitely misunderstanding each other somewhere. I think we may be working off some different assumptions about how the biology here works.

I weigh 185 pounds - plugging this into a metabolism calculator, my weight will stay stable at 2200 calories per day. Suppose I weighed 500 pounds. My weight would stay stable at about 4500 calories per day.

If the 500 pound guy got only 4200 calories per day, it doesn't matter how balanced the diet is or how many nutrients he has, his body has a caloric deficit and doesn't have enough energy to live. Hopefully it takes care of that by burning some of his stored fat. If it can't do that, he's going to be in big trouble.

I may be wrong about this, but I don't think the body can actually operate a a true caloric deficit. It WILL make up the deficit (or die, which also technically resolves the deficit). All it can do is do so in more or less problematic ways. The less problematic ways are things like burning fat. The more problematic ways are things like increasing appetite, decreasing exercise, and catabolizing organs.

I think your question corresponds to "But what if the body did just operate at a caloric deficit?", and I am really getting out of my knowledge comfort zone here but I don't think that's possible. Our analogy to economics here fails - we're not talking money where you can run a loss for a while and just have to worry about the bank coming after you, we're talking thermodynamics where it's physically impossible.

Weight loss is caused not by operating at a caloric deficit per se, but by the body avoiding caloric deficit by burning fat or other bodily tissues.

I could be totally wrong about this.