If pistachio nuts had a public-relations agent, she would have been mighty happy with the results of a recent study in the Journal of Agriculture and Food Chemistry.
The study was the most comprehensive analysis of nut and seed varieties to date, examining twenty-seven different products. Though pistachio nuts didn’t have the highest phytosterol content of all (that honor went to sesame seeds and wheat germ), they did have the highest phytosterol content of any product generally thought to be a “snack food”.
The main phytosterol identified in the nut and seed samples was beta-sitosterol, which is known not only for lowering cholesterol but for supporting prostate health.
Last year at the Food and Nutrition Conference and Expo, pistachios had a strong presence with two new research studies showing how the natural properties of pistachio can make for more mindful eating which in turn can help you reduce calorie intake without feeling restricted.
The S-L-O-W Down Shell
Dr. James Painter, a behavioral eating expert for more than 18 years and professor and chair of School of Family and Consumer Sciences at Eastern Illinois University presented his latest research in this area; two studies on “The Pistachio Principle,” which encompasses these mindful eating techniques.
“The research shows that our perception of how much food we need to become satiated and maintain a healthy body weight is skewed by many environmental factors,” says Dr. Painter. “We eat more food if we eat off of a bigger dinner plate; we’ll eat more potato chips if they come in a larger bag.”
Painter added that mindless eating essentially means we are ignoring hunger cues that tell us to stop, but said that small behavioral changes can help people eat less without feeling deprived.
In Painter’s first study, 140 subjects self selected a portion of pistachios as they entered the classroom and the weight of the selected portion was recorded. At the end of the class, the weight of the remaining pistachios was recorded and subjects were surveyed to determine their fullness and satisfaction.
In condition one, the subjects were offered in-shell pistachios and consumed an average of 125 calories. In condition two, subjects were offered shelled pistachios and consumed an average of 211 calories, a difference of 86 calories. Those who snacked on in-shell pistachios consumed 41 percent fewer calories compared to those who snacked on shelled nuts and fullness and satisfaction ratings were not significantly different. The shell changed the package of the pistachios, adding volume and it slowed consumption, allowing for hunger cues to be activated, reducing overall calorie intake.
Visual Cue to Cut Calories
In the second study, subjects were offered pistachios to eat at their desk over the course of 8 hours. A bowl of the in-shell nuts was provided, and refilled at regular intervals. But in one condition, the shells were allowed to keep mounting up, and the bowl holding the shells stayed on the subjects desk. In the second condition, the bowl with the empty shells was emptied every couple of hours.
When the shells were allowed to mount up, subjects consumed 18% fewer calories than when the bowl with the empty shells was periodically emptied. Interestingly, the fullness and satisfaction ratings were the same for both groups. (This study echoes one done by Brian Wansink in which he had guys chow down on buffalo wings; when the bones kept being removed by the waitress, the guys ate significantly more than when the bones were allowed to pile up on the table.)
The point: visual cues have a lot to do with how much we eat. The nature of pistachios makes it easier for people to be mindful of their snacking behavior- after all, you’ve got the proof of how much you’re eating right in front of you in the form of an escalating pile of shells! When those shells sit there, people are more mindful of their snacking behavior and calorie intake is reduced naturally without feelings of deprivation.
These and other studies underscore the notion that pistachios are a healthy snack to add to any weight management plan because they are a good source of protein and fiber. Pistachios also offer 49 kernels per serving – more than any other nut. Comparatively, almonds have 23 in a serving, walnuts 14 halves and cashews, 18.