In a two-arm, parallel randomized controlled trial, scientists from the University of South Australia and Texas Tech University examined the effect of consuming 35 g of lightly salted dry-roasted peanuts prior to two main meals per day as part of a weight loss diet, compared to a traditional low-fat weight loss diet, on body weight, markers of glycemic control, and blood pressure in adults at risk of type 2 diabetes.
“Overweight and obesity continues to be an issue of global public health significance,” said first author Dr. Kristina Petersen from the Department of Nutritional Sciences at Texas Tech University and her colleagues.
“In the United States, about 74% of adults aged over 20 years have overweight or obesity. Similarly, in Australia, 67% of adults had overweight or obesity in 2017-2018, an increase from 63.4% in 2014-2015.”
“Overweight and obesity significantly increase the risk of type 2 diabetes and cardiovascular disease (CVD). Dietary approaches that assist adults with overweight and obesity to achieve sustained weight loss are critical for diabetes and CVD risk reduction.”
“Substantial evidence shows that nuts are associated with a lower risk of these diseases,” the researchers added.
“The findings are supported by randomized controlled trials showing that nuts improve risk factors for CVD and markers of glycemic control.”
“In addition, nuts have high satiety value, and human feeding trials show that nut intake moderates appetite in the post-meal period. Notably, nuts, including peanuts, have been shown to suppress hunger and the desire to eat and increase fullness ratings following intake.”
“However, nuts are energy dense and often excluded from weight loss diets,” they said.
“Evidence to date suggests that nut intake does not promote weight gain in studies targeting weight maintenance. Few studies, however, have evaluated the effect of nut intake in the context of energy-restricted weight loss diets.”
“The aim of this trial was to evaluate the effect of intake of 35 g of peanuts prior to two main meals per day as part of an energy-restricted weight loss diet, compared to a traditional low-fat weight loss diet, on body weight, hemoglobin A1c (HbA1c), 2-h glucose, and blood pressure in adults with overweight or obesity at moderate or high risk of type 2 diabetes over 6 months.”
“It was hypothesized that the incorporation of peanuts into a weight loss diet would augment weight loss and improve glycemic control compared to a traditional low-fat weight loss diet.”
The study included two groups of Australian adults who were at moderate or high risk for type 2 diabetes.
The peanut-enriched group of 57 adults consumed 35 g of lightly salted, dry-roasted peanuts twice a day 30 min before meals. The control group of 50 adults was instructed to avoid eating any nuts or nut butter.
Both the peanut and control group received nutrition education from an accredited practising dietitian to follow an energy-restricted diet. Participants in both groups met with the dietitian monthly throughout the study.
After six months, the authors found that both groups lost a relatively similar amount of weight (6.72 kg in the peanut-enriched group and 6.6 kg in the control group), despite the peanut-enriched group consuming an extra 400 calories a day from the addition of a total of 70 g of peanuts to their diet.
Greater systolic blood pressure reductions were seen in the peanut-enriched group than in the control group. The peanut group lowered their systolic blood pressure by 5 mmHg, which is associated with a 10% reduction in risk for major cardiovascular events.
Both groups saw improved fasting glucose and insulin control, as well as improved HbA1c, which is a measure of long-term blood sugar control.
“Lightly salted peanuts are actually a low-sodium food, usually containing between 90-100 mg per serving,” Dr. Petersen said.
“Peanuts contain one of the highest levels of arginine, an amino acid that helps to dilate blood vessels and lower blood pressure.”
“They are an excellent source of magnesium, a mineral known to help regulate blood pressure.”
The team’s paper was published in the journal Nutrients.
Kristina S. Petersen et al. 2022. The Effect of a Peanut-Enriched Weight Loss Diet Compared to a Low-Fat Weight Loss Diet on Body Weight, Blood Pressure, and Glycemic Control: A Randomized Controlled Trial. Nutrients 14 (14): 2986; doi: 10.3390/nu14142986