Does calorie counting increases people's chances of a successful weight loss?
The study "Randomized Trial of Lifestyle Modification and Pharmacotherapy for Obesity" published in the New England Journal of Medicine, shows that people who frequently recorded their food intake lost more weight than those who did so infrequently.
Those in the combined-therapy group who frequently recorded their food intake lost more weight than those who did so infrequently (18.1+/-9.8 kg vs. 7.7+/-7.5 kg, P=0.04).
It should be noted that weight loss is not due to the fact of counting calories, but because of the calorie deficit created. And people who are monitoring their food intake have a greater chance of long-term success.