That's at least partially true, but there are serious issues with that explanation if you want to explain all of the effect. In particular, there really does

That's at least partially true, but there are serious issues with that explanation if you want to explain all of the effect. In particular, there really does appear to be something different going on in the last 2-4 decades or so affecting people's internal set points. When you compare to other recent historical times where there was also an abundance of food, people were self-regulating better than they are now.