But since Kardashian did use #Atkins with her Snap, it's worth looking closer at the low-carb diet, which was all the rage in 2003 and 2004, but has become a controversial way to lose weight in recent years.In 2013, the BBC reported that the diet made popular by the late Dr. Robert Atkins, which advised heavily cutting down on carbs, "advocated starving the body of carbs so it was forced to burn its fat stores to get energy — a process known as ketosis."The diet was considered controversial, because it went against the low-fat, high-carbohydrate diets that most nutritionists were recommending. While some have seen results, it's also been reported that the diet can cause kidney damage, heart disease, and could trigger diabetes in addition to putting you in a bad mood.Keeping that in mind, it's also worth asking whether or not Kardashian is being paid for her hashtag endorsement of the dieting plan. Kardashian has been known to use her likeness to promote weight-loss products in the past, including waist training and QuickTrim weight-loss pills.Kardashian's endorsement of the latter led to a class action lawsuit from users who claimed Kardashian made “unsubstantiated, false, and misleading claims” in ads, tweets, and interviews about the pills. That lawsuit was later thrown out.As People reported earlier this year, Kardashian signed up for the Atkins diet as a brand ambassador. Kardashian, who used Atkins after the birth of her first child, North, signed up for Atkins 40, which encourages its users to let up on some of the stricter rules of the original Atkins plan by having a more balanced diet. Atkins 40 promotes food options from each food group, including carbohydrates, protein, and fat, along with more servings of fruits and vegetables.