Already one of the lowest calorie nuts, pistachios actually contain fewer calories than what’s listed on the nutrition label. Most packages say a 1-ounce serving—about 30 grams, or roughly a handful—packs 170 calories. But the real number is more like 160 calories, finds a study presented at the Experimental Biology conference in Washington, D.C. Huh? Here’s the deal: Your body doesn’t absorb all the fat in the nuts, which means you get fewer calories than you think. Other studies have shown that your digestive system doesn’t fully absorb the fat from nuts like peanuts and almonds, but this is the first to measure the calories your body absorbs from the snack. “It is the physical property of nuts that makes the fat less available,” explains David Baer, Ph.D., lead researcher of the pistachio study and scientist at the U.S. Department of Agriculture’s Agricultural Research Service. “Nuts have cell walls, and that is where we find the fiber, which is not digested. The cell walls protect a lot of the fat from digestion, and you have to physically break that cell wall by chewing it or grinding it, like in a butter, to make the fat more available.” By the time the fiber gets broken down in the colon, it’s too late for some of the fat to be absorbed. Less fat equals less calories—good news if you’re trying to lose weight. It’s possible that the same “less fat, less calories” rule applies to nuts like almonds and peanuts, but researchers haven’t tested these in the same way as pistachios—at least not yet. “People shouldn’t shy away from eating pistachios because they are high in fat,” Baer says. In fact, the fat in pistachios may actually help lower LDL, or “bad,” cholesterol, he adds. That’s part of the reason eating nuts is one of our 100 Ways to Protect Your Heart and why we called nuts the Healthiest Snack Ever. Bored of plain nuts as a snack?