Despite their high calorie content, a daily intake of nuts might help people keep off excess weight, especially when they are substituted for less healthy foods, a recent study from Brigham and Women’s Hospital and Harvard Medical School in Boston suggests.
Researchers followed 126,190 healthy middle-aged adults for 20 to 24 years. At the start, participants were typically at a healthy weight or slightly overweight. By the end of the study, about 17% of participants had become obese.
People who increased their total nut consumption by a one-half-serving a day (14 grams, or about half an ounce) were 3% less likely to become obese. Boosting daily walnut consumption by a similar amount was associated with a 15% lower obesity risk, while adding tree nuts like cashews and almonds was tied to an 11% lower obesity risk.
How nuts might ward off weight gain
Increasing nuts in the diet may help maintain a healthy body weight in several ways.
Their high healthy-fat and fibre content are more filling for longer compared with refined (white) carbohydrates and other more easily digested, highly processed foods.
That way, eating nuts may benefit the overall quality of the diet by making less room for less-healthy snack foods.
Each year during the study, participants gained an average of 0.32 kilograms (0.71 pounds). But each half-serving of nuts added to a daily diet was associated with less weight gain.
With an added half-serving of nuts in general, people gained an average of 0.19 kg (0.42 lb) less every four years than those who didn’t add nuts to their diet, while adding a similar amount of walnuts was tied to 0.37 kg (0.82 lb) less weight gain and tree nuts were associated with 0.15 kg (0.33 lb) less weight gain.
The study also found that adding nuts to the diet was associated with a 4% lower risk of gaining more than 2 kg (4.4 lb) or more than 5 kg (11 lb) every four years.
Study limitations
The study wasn’t a controlled experiment designed to prove whether or how changes in nut consumption might directly impact weight gain over time.
Also, researchers relied on participants to accurately recall and report on their eating habits once every several years; it’s possible this might not reflect what they actually ate.
Authors on the study received funding from The Peanut Institution and the California Walnut Commission.
Source: The BMJ, online September 23, 2019.
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