Here is one topic that is confusing the hell out of people. Fat in a diet.
Is fat bad? Should we have any fat in our diet? How much, if so? What kind of fat? What about keto diets? Etc.
We used to believe that fat is bad and diets should be low-fat… I know. I was there myself. Luckily, I had an awareness of protein and knew that cereals, bread, pastas are of no good to me, so I focused on protein and veg. And this worked really well. However, it WAS missing a healthy fat element and luckily science has moved on and with that, the way we now think of a properly balanced diet.
Low fat diet frenzy started in the 70s and it took decades before we realised that it was not fat, but sugar and simple carbohydrates, that are a true enemy. Many low-fat produce, like yoghurt as an example, were just added sugar to taste better. Same with baked goods: they reduced fat, whilst increasing sugar to compensate and sold us the notion that low fat was healthier. Think of muffins, cakes, etc.