Researchers from the U.S. Department of Agriculture found that almonds contain 20 percent fewer calories than originally thought. The researchers examined the energy content of almonds using an updated method of measuring calories in food. The team found that while scientists once thought that a 1-ounce serving of almonds contained roughly 168 calories, it actually provides closer to 129 calories. A 1-ounce serving is about 23 almonds. This data means that a 100-calorie serving is equivalent to about 19 almonds.