Even though the diet does provide foods from serval food groups, registered dietitian Toby Amidor R.D. says it's not enough for complete daily nutrition—especially since high-calorie, low-nutrient foods like hot dogs and vanilla ice cream are part of the limited menu. "Due to the lack of adequate amounts of whole grains, vegetables, dairy, and protein, you won't be able to meet your complete nutrient needs over these three days," she explains.
Many diets, including Atkins and the keto diet, fit into this umbrella. A typical low-carb diet limits carbs to less than 60 g daily, but this can vary, according to the Mayo Clinic. (15) In a September 2015 review published in PLoS One, people following low-carb diets saw modest weight loss — although study authors note that long-term effects of the diet require further research. (16)