The key to weight loss is calories, not necessarily the type of food you’re eating, according to a recent study by the U.S. Department of Agriculture and researchers at Tufts University. They found that the study participants, who all cut their calorie intake by 30%, lost about the same amount as weight, even though some were put on a low-carb diet, and others were put on a low-fat, higher carb diet. The authors suggest that this study demonstrates that there are a variety of healthy diets that can encourage weight loss.