Answer: All of them.
All diets work (in the context of weight loss). As proven by many experimental diets as well as popular ones followed by millions. People slim down on a variety of approaches, macronutrient ratios, and food groups.
Calories exist. To argue that they don't is nothing short of an insult to our intelligence. And by "our", I mean every person who still holds to their sanity when discussing diets rather than holding out to their dogma. To the millions of people who lose weight simply by counting calories.
If our body didn't extract energy from a magical macronutrient that wouldn't make sense. Low-carbers often are led to believe by a few powerful voices in that dietary movement that fat is a magical macronutrient that the body not only avoids storing as fat, but helps the body burn fat. The truth is fat is the most energy dense macro, for the body to avoid using it as energy and storing it in excess is absurd. Pigging out on fat cannot avoid the consequences because of some belief you have adopted about fat, the reality remains, energy in excess is stored by the body, it doesn't disappear into another universe via some vortex that anatomical studies haven't found yet. The worst part is the Taubesian worldview not only promotes ad libitum calorie consumption, but denounces exercise as a method. That is just unhelpful.
Carbs do not make you fat, fat doesn't make you fat. All food contains energy, some foods more than others. Low energy, high nutritional density diets are supposed to be for people who do not or cannot maintain regular daily active exercise. For the rest of us we can have more than a little leeway.
When I examine these diets, such as 30BAD or WAPF, it's the people you see in the background you notice. Not the leaders but the followers. The person who writes to the Weston A. Price Foundation that they are gaining fat on the "nourishing" diet (which recommends copious amounts of butter), or the person who posts on the 30 Bananas a Day website that their clothes are getting tighter and they feel fatter eating all those calories from fruit.
Many kinds of foods contain nutrients that provide energy, youth and vitality. But a fattening lifestyle (sedentary living+excess calories) is a recipe for failure. No amount of well wishing can stop the body from storing excess energy as body fat.
Counting calories and portion control was the only thing that worked for me and I lost 100 lbs. I am not some freak of nature, I am not the exception, I am the rule. Millions do it this way and succeed. Others follow a certain diet and eat too much and exercise too rarely and fail. If you want to get down to a weight from being obese, you're going to have to have the willpower to control yourself. Because obese people don't need a religion, they just need a new approach in their life. Eat less, move more is too simple to sell a carb-restricting or fat-restricting approach to food.