They were probably overweight before they started Atkins diet, thats what I can recollect from the people who are on it. Also, many people don't really go into ketosis anyway, so there doing it wrong. If they are overweight on Atkins diet, then most likely they are consuming too many calories. In that case, they would be overweight regardless of the diet.
Why would someone go on atkins diet(or any diet) if they weren't overweight. Not overweight in BB language, but overweight/obese type people who don't workout. If they are still overweight after the diet, then they failed, but before atkins diet I'm sure they tried calorie restrict and failed with a normal diet too, but why doesn't anyone bring that up?