Although studies do show that people who change their eating habits and increase their exercise often maintain weight loss, there is more to the weight loss story. There are other factors such as genetics, environment, mental health and food intolerances which play a role in one’s ability to lose weight. Some researchers argue that the common advice to just “count calories” isn’t helpful, because it ignores the many issues, including biology, that contribute to a person’s weight. Researchers argue that rather than focusing on a calories-in versus calories-out equation, more attention should be paid to the overall composition of a person’s diet.