yes but they had some rat studies where the rats had the same diet and exercise but the poisoned ones were fatter.. There is a little more to the story about "fat = calories in vs calories burned in exercise". The body can do more things with calories than just move muscles..
on a personal level, my grandmother knew that starches made people fat. I mean, that's like 60 years ago. "Science" only figured that out about 1990 or so? She told us to not eat bread, potatoes, etc and we would not be fat. Recently I just stopped eating bread one day. I lost weight, my energy level went up.. then I saw a video of a 109 year old guy that had learned to not eat white food [white flour, potatoes, sugar, etc] early on in life.. so I stopped eating potatoes and wow, weight went down a tad more and energy further up the scale..