While individuals can find space for weight loss regimes, it really is a society-level problem.

Consider an experiment with two populations of rats. One population gets a normal amount of food, the other gets the same food with a bunch of added sugar. Of course the population with added sugar gets fatter. But, while the average rat may have gained 10% weight or whatever, on an individual level you'll see a wide range of results - some rats aren't effected by the increased sugar, some gain a small amount of weight, some gain a lot.

This is basically exactly what we've done to ourselves in capitalist society over the past seventy-ish years, taken our previous diet and jacked it up with a ton of sugar (and other additives and a lot of increased volume). But while with the rats it's easy to see that all you have to do to return the overweight population to normal is to stop adding sugar to their food, with humans we can't see that because we've created a system that blames you for getting sick.

It's like building a coal power plant in the middle of a neighborhood, and then blaming the residents when they start getting asthma or worse, and holding up the people who won the genetic lottery and don't get lung disease as the example we should all strive to replicate.