It’s the combination of carbs and fats.
Pretty much all the palatable high carb foods are also high fat: Pizza, ice cream, cookies, cakes, all fast food meals.
Keto certainly works well for weight loss but part of the reason is that by eliminating carbs you take out a lot of fats in the process.
A well formulated keto diet is very high fat, moderate protein. But yes, by doing keto the right way, you'd be eliminating lots of ultra-processed foods that are high in both carbs and fats (industrial "vegetable" oils).
Keto, when done right, works well not only for weight loss, but also to resolve many health problems. It certainly worked for me. I didn't start keto to lose weight.
Keto works for weight loss for many reasons, one of which is controlling insulin levels. When blood insulin is high, fat burning cannot happen because burning blood glucose and storing it, as glycogen and as fat, takes highest priority until blood glucose levels are back to normal.
It's no surprise what happens to a person's body composition when their blood glucose and insulin levels are high all day, every day, for decades because they consume too many carbs.
