no one eats fat, or carbs, or protein. We eat foods

Okay, but pork chops and pasta have very different proportions of the above. You can definitely structure your diet to weight towards one or the other.

In the real world we get all three together every meal, and if you’re not, it means you’re following a diet that you probably shouldn’t.

Angry JBP noises

More seriously, there’s plenty of dumb fad diets, to be sure. And now we’ve got a host of medications for basically shitting out all your calories faster than you can eat them to lose weight. But there’s definitely a problem in our general food delivery system, especially with regards to fats and sugars in fast foods.

Like, you can be blase about food composition. But there’s some shit that simply shouldn’t ever be in your diet (carbonated sodas, heavy preservatives in baked goods, lead). A lot of the “fad” aspects of diets tend to take these fundamentals and extrapolate them out to the extremes.