USA Today reported the results of an NIH study that people lost weight by restricting calories, regardless of type of diet. This really isn't new news, but rather an effort to cut through the hype of fad diets.
It is important to remember that weight management is about caloric balance: a caloric surplus (taking more calories in vs. burned) will result in weight gain, and a caloric deficit (more calories burned vs. taking in) results in weight loss.
Numerous studies show that those who have exercised along with caloric restriction saw weight loss from fat stores vs. diet-only groups, who saw weight loss from both fat and lean body mass.
In summary, if you want to lose weight, remember you must create a caloric deficit of 3500 calories to lose 1 pound of fat. Healthy weight loss is 0.5-2.5 pounds/week, and the best way to accomplish this is through a combination of daily physical activity + moderate caloric restriction.