A caloric deficit will produce weight loss. If you're arguing that this isn't sustainable due to the amount of calories being "requested" by people's subjective desires and experiences, that's a completely different (and also incorrect) argument.
There are many double blind studies on this. On a 2+ year time horizon, the huge majority of obese people who follow a "eat less exercise more" regime lose weight and then gain it back. This happens because the people never stop being hungry due to the disruption that obesity puts on their endocrine system. There are a number of medicines (saxenda, liraglutide, ozempic, mounjaro, wegovy) that produce reliable robust weight loss on a 2+ year time horizon. These medicines work best with a change in diet and exercise habits, but reliable weight loss on a population wide scale is not something you treat with "diet and exercise" advice.
Yes a lot of crash diets fail, for obvious reasons, but once a diet has stabilized the cravings will go away.
It does for many people mean they will need to cut out or dramatically cut down the eating out, drinking and instant meals. Most people don't want to do that.
Substantial weight loss is possible across a range of treatment modalities, but long-term sustenance of lost weight is much more challenging, and weight regain is typical1–3. In a meta-analysis of 29 long-term weight loss studies, more than half of the lost weight was regained within two years, and by five years more than 80% of lost weight was regained (Figure 1)4. Indeed, previous failed attempts at achieving durable weight loss may have contributed to the recent decrease in the percentage of people with obesity who are trying to lose weight5 and many now believe that weight loss is a futile endeavor6.
Obesity is a problem of modernity and specific cultures made up of people who didn't used to be obese generations ago. Are the populations around the world in which people aren't generally obese just filled with a large subset of the population constantly starving...or we agree that no such large subset is simply destined to obesity.
If we agree on this, then your argument isn't that people are destined to obesity, but rather that once they're obese, they have patterns of behavior that are extremely hard to break over a long term basis. That isn't the same as saying that weight loss is a futile endeavor, it's just saying that people who are obese are very often going to fail to stick to the patterns of behavior that resulted in weight loss.
My argument is that in 2022, the medical advise and consultation of “diet and weight loss is the solution to obesity” is not true on a population level. We now have other tools to address obesity that are both pharmacological (GLP-1/GIP acting) or surgical (bariatric surgery). We should stop admonishing patients for not following treatment guidance (eat less, exercise) and instead provide them with solutions that actually work reliably. I have nothing to add to the causes of obesity, and eating properly and maintaining a high level of activity are clearly good at preventing people who have never been obese from becoming obese.
Sure a caloric deficit will produce weight loss. Obviously. But reducing calorie intake alone does not guarantee a calorie deficit. While there is of course some level of unavoidable caloric expenditure, the average person has a fair bit of expenditure that is quite avoidable.
It is not hard for the body to discourage unnecessary caloric expenditure in response to a notable caloric deficit. Indeed, doing just that is a basic famine survival instinct.
Now given the decidedly non-famine conditions, eventually things should restablize, but it does mean for a person at caloric equilibrium, reducing caloric intake by say 500 Calories, will often not result in a 500 calorie deficit, but a smaller one for for quite some time until the body adjusts to this being the new normal.
In the mean time, the person likely feels like shit. Furthermore, If there actually is food available, the body and subconscious mind is doing everything it can to encourage the person to eat more.
This substantial resistance of the body to attempts to run meaningful caloric deficits for an extended period are a not insignificant portion of why "dieting" often fails. People don't stick with it, since it majorly sucks.
