There is a lot of missing science here - yes we have the whole 'calories in - calories out', but we are missing some detailed biochemical descriptions of what's

There is a lot of missing science here - yes we have the whole 'calories in - calories out', but we are missing some detailed biochemical descriptions of what's going on. The human body is more complex than a 2 term math expression using subtraction. For example, we do not really fully understand the role of biochemical stress hormones, and weight gain. Or how exactly insulin, leptin, cortisol, inflammation markers (eg: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4155060/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4155060/) all interact. Note that leptin is created in adipose tissue, potentially suggesting a cycle - and this is something borne out in experience, it is harder to lose weight the more you have to lose. Definitely an area of research to learn more. The epidemiological approaches reveal interesting things, but there are a lot of variables, hidden and not, that is pointing that the advice accumulated from these studies is not really having the impact we want. After all, the current advice is "hey do this thing that is very hard for you to commit to, and has uneven outcomes". Some research even references 'the big loser' because of the inability of people to maintain weight losses. Typically discussions about this devolve very quickly into coded (and not so coded!) shaming. "unhealthy food habits"? How about "unaffordable healthy food" or "habit forming unhealthy food"? Why not that framing? Go to any average 7-11 and enumerate the list of products that aren't designed to generate "repeat customers". Bananas (in-so-far as they are sold) and water are the only ones I can come up with. Non-edible items not eligible.