Even though nuts are brimming with excellent nutrition, sometimes you shy away because of the calories. But here's a nut that may have fewer calories than you think: pistachios.

A new study suggests that human bodies don't absorb all the calories in pistachios, because the fat from this nut isn't readily absorbed by the intestinal tract.

What's in a Calorie?
Proteins, fats, carbohydrates, and alcohol have been assigned a simple caloric value most dieters know by heart. Protein and carbs supply 4 calories per gram of food while fat supplies 9 calories per gram. And alcohol lands in the middle -- at about 7 calories per gram. But in light of this new study, researchers believe that these caloric factors may be outdated and may overestimate calories. And the researchers figure that the caloric value of pistachios is probably overestimated by about 6 percent, given the number of calories that actually get absorbed.

Here are two more reasons you should stock your pantry with pistachios:

• You'll breathe easier. A clinical trial revealed that eating 2 ounces of pistachios per day raised serum levels of gamma-tocotrienol, a member of the vitamin E family linked to a decreased risk of lung cancer.
• You'll improve your cholesterol profile. In a study where 20 percent of people's daily calories came from pistachios, the participants experienced significant improvements in their cholesterol profiles.