> Nutrition experts say that besides their potential for harm, these popular diets are really hard to follow

You can probably attribute this more to the current food environment and less so the diet. If you only have access to food that agrees with your diet, it's pretty easy to follow. Restrictive food diets are difficult because all the restricted food (generally the restricted foods are ones that are full of "empty calories" or contribute to overeating) surrounds us. It's everywhere. Restaurants. Commercials. Grocery stores. Convenient stores. The break room. Your S.O.'s pantry. If you can manage to escape it, your diet is smooth sailing. Good luck over eating spinach and hard boiled eggs, your stomach will revolt.