Dr Atkins goes into great derail about his FAT FAST. With a number of menu items.

One is an 8 oz. block of cream cheese.

His point was to use this if 20 carbs didn't work. It was for the rare person. And not to follow for more than 5 days.

Me, I can skip all meals for one day. But one food passes these lips, its full meals. Not ,400 calories. Too low signals "starvation" to the body and it goes into survival mode.

Keto and carnivore, at higher calorie intake, overrides this traction. Dr Atkins showed that higher calories on keto worked better to drop body fat. Not less.