I guess it depends on how strictly one wishes to define "disease." I would not be willing to term being fat or obese a disease but as a normal variant as a result of life style, physical tendencies, psychological tendencies, culture, subculture, and the like. Western cultures now value youthful slimness and stylish fitness, but a century ago being fat was considered prosperous, important, "weighty."
For a while there, it seemed as if obesity were almost a requirement of a US President. I think Trump is the fattest President we will have had in a long time. Who was the last fat President of the US, not counting Bill Clinton whose weight varied a good deal and who now looks underfed if not ill?
I think it's a stretch to term a physical condition a "disease." We do not term physical weakness "a disease," or being "uinderweight" unless you have anorexia. Many or maybe even most fat people seem comfortable with it, and accept the trade-off of tasty carbs vs. being light on their feet.
Anyway, government money is flowing into research so now being fat is suddenly a disease needing medical treatment. In the US, the expanding "disease" label is often about money. Example: One Weight-Loss Approach Fits All? No, Not Even Close.
When human variations occur on a bell curve, you can get away with drawing the vertical line of "abnormal" wherever you want. That's where America's "obesity epidemic" came from.
