"Atkins put fat back in the diet, but the problem is there’s no difference between artery-clogging saturated fat and heart-healthy unsaturated fat," says iVillage Health Editor-at-Large Madelyn Fernstrom, PhD. "There are also very few whole-grain starches and very limited fruits and vegetables. People like the immediate water loss because when you restrict carbohydrates, you lose water. But when followed as directed, it’s not balanced. To improve Atkins, look for lean proteins and add more fruits and veggies."