The biggest losers: Metabolic damage or constrained energy?

That the body is a complex buffered system of variable effeciency is not in dispute - nor is it intractable with the thermodynamic position.

It is always realistic to achieve a thermodynamic deficit, that there is some buffer or hysterisis to the curve (i.e non linearity) is not a big deal. The key insight is that the variability in the effeciency of your metabolism is not the bounding factor. A standard deviation of a few hundred calories in the natural variability of metabolism will meaningfully increase the difficulty of weight loss, but this simply means modulating the duration of your activity taking into account the diminishing returns of increased exercise and natural variability in metabolism. Now if this is psychologically or practically easy is an entirely different question.

With obesity there is a constant refrain that people should be able to deal with it by willpower alone. Here is an analogy to explain why this is unrealistic:

A while back I had a massive immune reaction in my skin, which brought with it the constant urge to scratch. A lot of people idly comment that the solution is to just not scratch, but it turned out that I had a skin infection, and under those circumstances the instinct to scratch is incredibly strong; you do it as soon as your mental attention is turned elsewhere. Once the skin infection was cured, and a bit of steroid cream applied the urge to scratch went away.

Now imagine how strong is the instinct to eat. Eating is essential for life, the instinct to eat when hungry has been reinforced by evolution constantly since the nervous system developed. Have you read a description of what it's like to starve? The brain can think of nothing but eating, peoples behaviour becomes quite extreme. Some people do overcome it - those who starve themselves to try to save their children, for example. But that's an enormous external motivation.

There's a bit of cognitive dissonance in seeing a hugely fat person and trying to imagine that their nervous system is for some reason acting like they are starving. It's a lot easier to imagine that they just don't have the willpower to resist that extra snack, which is a situation a lot more familiar to most of us. But it seems likely that the further is more correct.

Perhaps you should read your own sources. From the abstract of the second study: "At the 3-year follow-up, 53% of the original sample (of 621 persons) maintained losses of 5% or more and 35% losses of 10% or more.". From the third study: "When successful weight maintenance was defined as maintaining a weight loss of 5% or 10% of initial (pre-treatment) body weight, 40% were maintaining a 5% weight loss at five years and 25% were maintaining a weight loss of 10% at 7 years." The other studies also don't back up your 0.1% estimate.

Your initial statement is completely misleading and shockingly you have provided hard evidence against it.

For the first 43 years of my life I was kind of always overweight. Not always obese but there were periods. I've also always known that it would be healthier to have less fat, so it was always a thing on my mind.

But, I was also always hungry. Mostly not starving, but just hungry. I could eat a big meal, that made my stomach feel physically full, even painfully so and still have the feeling of hunger.

Of course, I also understood that on pure physics terms it really is calories out vs calories in that makes the difference. So I did try to eat less.

Also, you read and see people eating a salad and at the end saying, "oh, I feel so full". I always tyhought they were lying, because that never happened to me, so I kind of dismissed it as bragging or something.

Now, could I eat less food? Yes, of course, but it's always a struggle. Every day, all day. And if you fail once, that's that week's gains gone. Imagine there's a fly that's buzzing around your face 24/7 and you can't swat it away, you just have to live with it and if you have a bad day and swat it away for just a bit, you get fat.

Some time ago I took ozempic for the first time and that's when I realized that yes, in fact, it is possible to eat a salad and feel satisified and full after that. Even after more than a year on semaglutide I'm still amazed at how little food I actually need. It kind of feels like I should have died by now due to lack of input calories. But I'm feeling great and almost to normal weight now!

For me the change of how I felt was really something I could not even have imagined before, that you could actually not think about food all the time and kindof ignore it and not really get hungry. And eat just a little and feel full. Amazing. But two years ago I could not have imagined that this is possible, as it had never been before.

This of course led to the realization that the opposite is true for some people, who have better regulation of whatever chemical makes you hungry. Apparently there are lots of people for whom feeling hungry after eating a large meal seems impossible. And since this is something they have never experienced, it's not really reasonable to expect them to understand or be able to imagine it. I wasn't able to imagine the reverse!

So yes, it is possible for everyone to lose weight just by commiting. But it is much harder to commit in a specific area for some people than others. Commiting to a lifetime of always being hungry is very very hard over the long term.