Twin doctors, one eats nothing but fats and the other eats nothing but carbs, for a month. They document it, they work out, they do tests.
The result (spoiler alert), either is not great. Eating only fat cannibalizes your muscles, and makes you not get any enjoyment out of food. Whereas eating only carbs makes you feel hungrier all the time.
But their conclusion had a twist, the main problem is processed foods that have a 50/50 mix of fat and carbs. An excellent example is whipped cream. Your body would reject you drinking pure cream, and also pure sugar. But mix them together, and you cant stop eating it! Same with many of our favourite foods, ice cream, doughnuts. All have the 50/50 mix that vendors long ago realized was the most addictive mix. Your body basically never gets the signal to stop eating.
Anyone who is interested should check it out.