Pistachios & Weight Management Research

Results from several recent studies suggest that adults who consume nuts, such as pistachios, may have a lower body weight and decreased prevalence of health risks such as heart disease and metabolic syndrome. They also tend to have better diets compared to people who don’t regularly eat pistachios.

Eating pistachios is also correlated with better weight control, possibly through increased satiety, and lower metabolizable energy. In June 2013, Dr. Flores-Mateo et al. reported in the American Journal of Clinical Nutrition the results of a meta-analysis of 33 clinical nut-feeding studies that compared the body weight outcomes of a control diet to a diet containing nuts. The researchers found that nuts, including pistachios, did not increase body weight, waist circumference or body mass index.
[Flores-Mateo G, et al. Nut intake and adiposity: Meta-analysis of clinical trials. Am J Clin Nutr. 2013;97:1346–1355]

Pistachios may help manage weight in the following ways:

• In-shell pistachios may slow down eating
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, et al. In-shell pistachio nuts reduce caloric intake compared to shelled nuts. Appetite. 2011;57(2):414-7]

• Leaving nut shells visible helps to gauge how many pistachios were eaten
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 the shell can provide taste satisfaction and an easy reminder of portion control.
[Kennedy-Hagan K., et al. The effect of pistachio shells as a visual cue in reducing caloric consumption. Appetite. 2011; 57(2):418-20.]

• Pistachios may have fewer useable calories than previously thought
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, et al. Measured energy value of pistachios in the human diet. Br J Nutr. 2011; 28:1-6.]

• Nutrients in pistachios contribute to greater satiety
A study reviewed 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.]

Below you’ll find a handful of recent studies on pistachios and weight management.

Bes-Rastrollo M, et al. Prospective study of nut consumption, long-term weight change, and obesity risk in women. Am J Clin Nutr. 2009;89:1–7.
• 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 with weight control when included in a balanced diet.
Dreher ML. Pistachio nuts: composition and potential health benefits. Nutr Rev. 2012;70(4):234-40.
• This review examines the nutrients and phytochemicals in pistachios as well as the potential health effects of these nuts.
• A growing number of clinical studies suggest potential health benefits of pistachio nuts.
• Five published randomized clinical studies have shown that pistachios have a beneficial effect on blood lipid profiles. Emerging clinical evidence suggests that pistachios may help reduce oxidative and inflammatory stress and promote vascular health, glycemic control, appetite management, and weight control.
Hernandez LM, et al. The effects of consuming a pistachio snack versus a refined carbohydrate snack on blood lipids, blood glucose, body weight, and body composition in young healthy adults. FASEB J. 2012;26:1b396.
• The goal of this study was to determine if pistachio nut snack consumption would favorably affect plasma lipid profiles, food intake, body weight, and body composition in a non-obese, normolipidemic population compared to a refined carbohydrate snack.
• 41 healthy men and women snacked on either pistachios or pretzels twice daily for three weeks.
• Body weight and percent body fat were significantly decreased in the pistachio snack group. No significant differences were detected within or between groups for plasma total cholesterol, LDL-c, HDL-c, triglycerides or blood glucose (P>.05), but a trend towards a significant increase in serum triglycerides in the pretzel snack group (P=.056) was detected.
• Results suggested that short-term consumption of a pistachio nut snack can decrease body weight and percent body fat as compared to a refined carbohydrate snack in young, healthy adults.
Li Z, et al. 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. 2010;29(3):198-203.
• 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.