Once upon a time Henry Ford stated that if you want an affordable automobile, you can have any color you like so long as it's black. Most people, especially businessmen, thought he was a genius.
And then there was Robert Atkins, who claimed that if you need to lose weight, you can eat any foods as much as you like so long as you limit carbohydrates. Many people, including scientists, thought he had lost nothing but his mind.
Now a scientific study published in The New England Journal of Medicine proves Atkins was right after all. Not only was a diet that restricted only carbs shown most effective for losing weight, it was actually healthier than diets that restricted total calories, saturated fat and cholesterol.
The study followed three groups of people for two years. The Mediterranean and Low-fat diet groups restricted their total energy, fat and cholesterol intake. The Low-carb diet group could eat unlimited amounts of whatever foods they desired, as long as they restricted their carbohydrate intake to 120 grams per day (20 g/day for the first two months).
I believe the mystery of how an unlimited diet can be healthier than restricted ones can be explained.
First, in practice there must be a certain limit of how much fat and protein one can comfortably eat, before feeling absolutely full and satisfied for hours.
Second, there is an unfortunate misunderstanding that Atkins-type of low-carb diet means eggs, meat, cream and butter only. I guess there could be happy low-carb vegetarians out there, at least theoretically speaking.
Anyway it's perfectly possible to eat a healthy amount of vegetables and even some fruit without exceeding the 120 g/day limit of carbs. For example, 1.8 kg (4 pounds) of apples would contain about 120 grams of carbs.