Snacking on a one-ounce handful of almonds might add only 129 calories to your diet-24% fewer than previously thought. The recalculation by USDA Agricultural Research Service scientists, published in the American Journal of Clinical Nutrition, may have implications for the calorie counts of other nuts as well as whole grains. The rigid structure of cell membranes in almonds (and possibly other plant foods) may lock in some fats and keep them from being digested, scientists said. That would explain why, when almonds were fed to 18 volunteers, an ounce didnt deliver the expected 168-170 calories. Most calorie counts use the Atwater general factor system, developed in the late 1800s and early 1900s, which assigns calories per gram of carbohydrates (four), protein (four), fat (nine) and alcohol (seven). But if some of the fat in almonds never gets digested, the actual calorie impact would be lower; this would apply to whole almonds, researchers noted, while ground nuts might be more completely digested. The same ARS lab last year reported that pistachios contain 6% fewer calories than previously thought.