Prior to the late 70s/early 80s, there wasn't any "scientific research". People consumed a high amount of animal fat, they used butter, and they didn't toss the egg yolk because it had too much cholesterol, and oddly enough, there wasn't an obesity epidemic. It wasn't until studies that said consuming fat is what led to heart disease (studies that had confirmation bias written all over them) that obesity rates in this country ed and we started seeing type 2 beetus in teenagers because people replaced the fat in their diet with added sugar. Point being, it's not just a few obscure studies I'm referring to, the last 30-40 years are loaded with evidence that sugar/carbohydrates are much worse for you than animal fats/cholesterol.