I don't speak for Atkiners, but here is my 2 cents. The first goal is to get fat adapted and replacing glucose with ketones. During this period, you should eat as much fat and protein as required to keep you on plan. Once you are fat adapted, your appetite may be reduced, essentially becoming self regulating. However, this doesn't happen for everyone, and if it doesn't, you may need to count calories to continue losing weight. That doesn't mean adopt a strict low calorie regime, but as the quotes provided by JEY100 suggest, calories do matter.