New information is coming out that seems to imply that the content of the fats we eat have effects on the body. Unsaturated fats seem to be obesogenic and interfere with the body's satiation mechanism, increasing the amount of white fat and decreasing the amount of brown fat (which is more metabolically active and may be the kind of fat that is lost first when people start dieting, which would explain part of the yo-yo dieting lose a lot of weight and then get stuck and gain more back system that plagues the obese), and the American food purity aesthetic has been pushing for the elimination of saturated fats from the diet as they typically come from animal sources.
Once the body hits a tipping point with excess white body fat, the fat becomes a sort of parasite which gets preferential treatment in consuming calories and nutritional resources out of the bloodstream, starving the organs while the body is bathing in an abundance of calories and nutrition.
If this turns out to be the whole story it is really quite insidious!
I don't know of a single-prong approach to solving this issue. Maybe wegovy will come down in price and help people break the cycle, maybe keto is the way to go, intermittent fasting may be helpful, finding saturated fats or supplementing with stearic acids and eliminating antioxidants to help promote fat oxidization... The list goes on for potential cures and we still haven't even begun work on solidifying the direct cause of the disease.
And yes, obesity is a disease. It's not just lazy people shoveling doritos in their faces and reaping their just rewards. The foods that we are provided are not balanced nutritionally and they have been designed by food scientists to not trigger the satiation mechanism so that we will consume more of them.
So yeah, when you eat processed foods your brain is tricked into thinking one more bite will satisfy, but the satisfaction never comes. Then you overindulge, getting lots of fast carbs and unsaturated fats, your body produces insulin, the calories get converted into white fat, the white fat grows, eventually becoming a parasite that eats your food first while you still haven't dealt with the initial issue, you become obese and since your white fat gets to eat first every time you eat you become more fat before your organs and muscles get the leftovers.
That's positively devilish, and right now the solution seems to be to intermittent fast so that your other organs get moved ahead in the nutritional priority list, to eat keto so that your body begins rapidly oxidizing fat, to limit vitamin C and other antioxidants until you get closer to your goal weight to limit your body fat's resistance to oxidization, and to supplement your diet with chemicals that help your body bypass the labyrinth of obesity you've found yourself in.
And despite all of that, we still don't know the full story.
https://fireinabottle.net/category/the-scd1-theory-of-obesit...
https://www.scientificamerican.com/article/how-sugar-and-fat...
https://www.nytimes.com/2013/02/24/magazine/the-extraordinar...