There has been a good deal of research lately on what constitutes the best diet for weight loss: low fat? low carb? high protein? high fiber? I think the researchers are asking the wrong question. Any calorie-controlled diet works, at least in the short-run. But research shows that no matter what diet they choose, most people regain whatever weight they've lost. I think dieters need to consider what is the best kind of diet for them as individuals, that is, what is the healthiest diet they can stay on for life.
There's really no sense in reducing calories to a level you can't sustain for the long-run or cutting out favorite foods that you'll eventually return to anyway or trying to follow an eating plan that is too inflexible to fit into your lifestyle (e.g., traveling or restaurant eating). Yes, to lose weight you'll have to reduce your calories, you may need to decrease (but not necessarily eliminate altogether) your intake of unhealthy fats and sugary foods and increase your intake of lean protein, healthy fats, and fiber (especially through fruits and vegetables). But you also need to learn how to eat modest portions of your favorite foods, as often as every day (pages 120-123).
What's the best diet? Let's change the question. What's the best diet for you?