Love’em? Eat up! A one-ounce serving may be high in fat (make that healthy fat) and calories, but new research shows that 55-75 percent of the calories in nuts are not fully absorbed by the digestive tract. So where do they go? Nut calories are mostly excreted by your body. Gross? Yes, but this is one of the reasons why nuts have been proven to help with weight loss and maintenance.