Highly unlikely. The obesity epidemic is very well explained by diet and lifestyle choices, and regional variations in average body mass correlate with these explanatory variable pretty well.
Even our pets are getting fat.
Previous experiments both natural and manmade indicate that homeostasis prevents long term weight gain in situations of high caloric availability.
The conclusion of the paper was that something was introduced into the environment in the 70s that is disrupting humans’ and nearby mammals’ homeostasis mechanisms.
We are less active and we're eating more. Thus we got fat.
I did similar things where I probably had 10k steps a day in Europe because we walked everywhere all the time. We also ate a lot and often. So my weight didn't change. Heck, I thinks some people gained.