That's how it's supposed to be and it's definitely what Atkins himself believed. And while I don't think it applies to most bodybuilders doing keto or a version of it, I think it incorrect about Atkins dieters in general. The sedentary who start a keto diet most likely do eat fewer calories to start, but not for long. They wind up eating as many if not more kcals than they were on a traditional diet once they get tired of meat, eggs, and vegetables, and start eating a lot more bags of pork rinds with cream cheese, Atkins food products, sugar free junk, etc.
Whenever the Atkins diet made one of its comebacks in 1998 or so, I was a waiter, and we had all you can eat prime rib once a week. I hadn't heard of Atkins at the time, and a couple having dinner told me about it, how it was making a comeback, was originally popular 20 years prior, etc. Dude was overweight, but said he had already lost 12 pounds in two weeks. He ate a shitload of fatty prime rib...certainly 3K kcals. Seems like appetite suppression didn't apply to him.