At a societal level? Almost certainly ozempic, but I will offer an alternate point which applies more to me and I imagine others:

Personally, I gained much more weight than normal during covid/lockdowns by eating worse and moving around & leaving the house much less than I had before. Took a couple years before the weight gains hit a threshold I couldn't tolerate, but once I did I lost 30lbs.

So if the baseline is only a few years ago, I will note that a *lot* of people gained a lot of weight in 2020-2022.

Ozempic has been super valuable for many people to lose some of that weight, but I also suspect the data is starting from a high point.