Turns out this myth is crazy.
For decades it has been widely believed that eating nuts causes weight gain.
Nuts in particular are high in calories and fat, leading to skepticism about whether they should be incorporated into a healthy diet.
However, a groundbreaking new study published in Nutrients has found that nuts do not cause people to gain weight and may in fact lead to a loss of belly fat.
Scientists at Vanderbilt University Medical Center looked at 84 millennial adults (ages 22 to 36), a demographic that has increasing rates of metabolic syndrome (MetSx), a set of conditions that increase the risk of heart disease and diabetes. .
Millennials had at least one risk factor for MetSx, such as high blood pressure, high blood glucose levels, excess body fat around the waist, or abnormal blood cholesterol levels.
Participants were fed one ounce of unsalted mixed nuts, such as pistachios, or one ounce of a carbohydrate-based snack, such as unsalted pretzels or whole-grain crackers, twice a day for 16 weeks. They imposed no additional dietary restrictions or changes in lifestyle habits.
“We specifically designed the study to be able to investigate the independent effects of nut consumption on body weight, ensuring that the number of calories participants ate during the 16-week intervention period matched the number of calories they expended each day. , which is one of the overall strengths of the study design and results,” Heidi J. Silver, PhD, RD, of VUMC, said in a press release.
The researchers found that the walnut-consuming group had significant health benefits, with a 67% reduction in MetSx risk for women and a 42% reduction in MetSx risk for men.
Those in the nut-consuming group also saw no changes in energy intake or body weight over the 16-week period.
For women, the study found that eating nuts led to a reduction in abdominal fat, which can lead to MetSx, diabetes, and heart disease. For men, research showed that eating walnuts reduced blood insulin levels.
The nut-eating group was also able to convert fat intake into energy more efficiently than those who ate the carbohydrate-based snack, which could be why the nut-eating group did not maintain body weight or body weight. fat.
“This carefully designed and well-controlled study shows that eating nuts, such as pistachios, does not have to cause weight gain and can be an important part of anyone’s health care routine in 2024,” Silver explained. .
The Dietary Guidelines for Americans state that more than half of Americans currently do not meet the daily recommendation of five to seven ounces of nuts and seeds per week.
However, the authors noted that more research is needed on the cardiometabolic response to nuts in other population subgroups.