This section briefly summarizes in less technical terms the results of scientific research related to pistachio nuts. Full details can be found in the published article. The studies are listed in chronological order.
One-hundred-forty university students were each given a 16-ounce cup filled with pistachios, shelled or in-shell and asked to self-select a portion. Students given the in-shell pistachios ate an average of 125 calories, while those given shelled pistachios ate 211 calories—41% more calories. The authors suggest that the in-shell pistachios slowed eating time, which may have contributed to less food intake.
Honselman CS, Painter JE, Kennedy-Hagan KJ, Halvorson A, Rhodes K, Brooks TL, Skwir K. 2011. In-shell pistachio nuts reduce caloric intake compared to shelled nuts. Appetite. Oct;57(2):414-7
One-hundred-eighteen men and women working at a university were each provided with two bowls at their desks – one filled with 4 ounces of in-shell pistachios and the other for the empty shells. The bowls were refilled with pistachios throughout the day. Some had the empty shells removed throughout the day and for others the empty shells were left at the desk. Keeping the empty shells at the desk resulted in 48 fewer calories eaten, without sacrificing fullness and satisfaction. The authors conclude that having a visual cue of how much is eaten is important for moderating food intake, and they suggest that eating pistachios in their shell can provide taste satisfaction and an easy way to remind ourselves how much we ate.
Kennedy-Hagan K., Painter JE, Honselman C, Halvorson A, Rhodes K, Skwir K, 2011. The effect of pistachio shells as a visual cue in reducing caloric consumption. Appetite. Oct;57(2):418-20.
Sixteen men and women between the ages of 29 and 64 ate either 0, 1.5 or 3 ounces of pistachios per day as part of a controlled diet. Blood, urine and feces were collected. Calculations showed that the actual calories used from the pistachios were lower than what was previously thought. The authors speculate that the dietary fat content of nuts may be resistant to absorption.
Baer DJ, Gebauer SK, Novotny JA. 2011. Measured energy value of pistachios in the human diet. Br J Nutr. Jun 28:1-6.
Fifty-two overweight men and women ate a diet containing 500 fewer calories per day than needed, which included either 240 calories of salted pistachios or 220 calories of salted pretzels. After 12 weeks, both groups lost weight, but those eating pistachios tended to lose more weight. The authors conclude that pistachios as a portion-controlled snack can be part of a successful weight-loss diet.
Li Z, Song R, Nguyen C, Zerlin A, Karp H, Naowamondhol K, Thames G, Gao K, Li L, Tseng CH, Henning SM, Heber D. 2010. Pistachio nuts reduce triglycerides and body weight by comparison to refined carbohydrate snack in obese subjects on a 12-week weight loss program. J Am Coll Nutr. 29(3):198-203.
This study reviews the various ways that nuts, including pistachios, may help maintain body weight. A main reason may be that eating nuts makes one feel full, resulting in eating less food at one sitting and being less hungry to eat again. This may be due to the many nutrients, such as fiber, protein and healthy fats, as well as the need to chew, which slows the eating process. In-shell pistachios have the added benefit of slowing eating time. The authors conclude that, even though nuts are calorie-dense, they have other attributes that make them appropriate for weight management.
Mattes RD, Dreher ML. Nuts and healthy body weight maintenance mechanisms. 2010. Asia Pac J Clin Nutr.;19(1):137-41.
Because nuts contain fat, there is the misperception that people who eat nuts may weigh more. To study this, over 50,000 women between the ages of 20 and 45 years were asked about their intake of nuts, including pistachios, over 8 years. Those women who ate nuts 2 or more times per week tended to weigh less. The authors conclude that eating nuts does not lead to greater weight gain and may help weight control when included in a balanced diet.
Bes-Rastrollo M, Wedick NM, Martinez-Gonzalez MA, Li TY, Sampson L, Hu FB. 2009. Prospective study of nut consumption, long-term weight change, and obesity risk in women. Am J Clin Nutr. Jun;89(6):1913-9.
To learn more about the health benefits of nuts in general, visit nuthealth.org.