CHICAGO (Reuters) - Diets high in protein may be the best way to keep hunger in check, U.S. researchers said on Thursday in a study that offers insight into how diets work. They found that protein does the best job at keeping a hunger hormone in check, while carbohydrates and fats may well deserve their current nasty reputation. The study, which will appear in the Journal of Clinical Endocrinology & Metabolism, looked at the effectiveness of different nutrients at suppressing ghrelin, a hormone secreted by the stomach that stimulates appetite.