Deadly Combination of Sugar + Fat !
In nature foods high in carbohydrates and fat are very rare. Processed food items such as doughnuts contain around 11 grams of fat and 17 grams of carbohydrate in a single serving. Since these food items are relatively new when compared to the evolutionary timeline, our brains are not evolved to have a response to them. A study in 2018 showed that the reward centre of the brain values foods high in both fat and sugar more than foods containing only fat or only carbs. This is why junk foods such as pizzas, burgers and pasta with creamy sauces trigger our brains in crazy ways that makes it harder to resist them.
Both fat and carbs are high value in the wild because they are energy dense. However our ancestors rarely would have found them together. A potato has lots of carbs, and no fat. A deer has fat, no carbs. Put them together, add salt, and sugar, and you have an irresistible mix.
Practically all junk food that you overeat follows this recipe. Burger: fat in meat and cheese, carbs in fries and bun, sugar in sauce, salt in meat. Pastry: carbs in dough, fat in oil, salt and sugar aplenty. Doughnuts and cookies: sugar + carbs + oil, with a little salt. Chips: carbs in oil with plenty of salt, and now sugar or a sauce full of sugar. Pizza: carbs in dough + fat in oil and cheese with a lot of salt, sugar in ketchup or sauce. Even many salads: carbs in croutons, fat and sugar and salt in sauce.
Ref: As more and more countries adopted the Standard American Diet, aka succumbing to these hacks, their residents became more and more fat.