Part of it is addiction to sugars and carbohydrates. Sugar strongly stimulates the reward centers in our brain, so companies pump everything with it to hook customers. People eat that shit to deal with stresses, often caused by other economic externalities, and eat too much of it thanks to low nutritional value. Some children are both obese and malnourished, because their food is so shitty. Companies don’t care about the health consequences; they only make stonks go up.

Body positivity doesn’t necessarily say being overweight is good, just that you don’t need to hate your body if you’re overweight. Shame can easily turn maladaptive, so not dwelling on self hatred is often a good idea. People do take it too far, as health consequences of obesity are real, but that isn’t representative of all body positivity. Body positivity isn’t always good, and isn’t always bad. Black and white simplistic thinking will often lead you astray.