> despite in many ways being as genetic as getting breast cancer.

This claim is utterly silly on its face. Look at pictures of folks in the US 60 years ago compared to today. The population did not randomly mutate a genetic condition towards the propensity of obesity. Folks who come from societies that are not all that overweight did not magically develop a genetic condition upon immigrating to the US. This claim is entirely non-credulous and most folks claiming such are doing so in bad faith.

Environmental is by far and away the largest factor. Meaning most everyone lives surrounded by highly palatable horrible-for-you food and lives extremely sedentary lifestyles entirely optimized for convenience.

It's really not something that needs ANY more examination than that. Fixing it is the hard bit. Everything else on top of this is a rounding error and not something that needs to even be discussed until the first order factor is fixed. Then we can start discussing nuance, outliers, and details. It's a waste of time otherwise.

GLP-1s are the only thing that has turned the tide even a little bit. Because people eat less. Any other benefit from that is again - secondary and perhaps interesting, but not the primary mode of action. GLP-1s proved it is the American diet that is the problem.