Increasing nut consumption by just half a serving/day may stave off weight gain and lower the risk of obesity, according to the results of a large, long-term observational study.
On average, US adults add on 1 lb every year. Substituting unhealthy foods (eg, processed meats, French fries, and potato chips) with 0.5 servings/day of nuts may be a simple strategy to ward off the gradual weight gain that often accompanies the aging process.
“Our results indicate that increased consumption of total nuts or any types of nut (including peanuts) is associated with less long-term weight gain, despite being calorically dense. Incorporating nuts as part of a healthy dietary pattern by replacing less healthful foods may help mitigate the gradual weight gain common during adulthood, and beneficially contribute to the prevention of obesity,” stated researchers, led by senior author Deirdre Tobias, DSc, Department of Nutrition, Harvard University T.H. Chan School of Public Health, Boston, Massachusetts.
Tobias and colleagues published the results online on September 24, 2019, in BMJ Nutrition, Prevention & Health.
The researchers analyzed information on weight, diet, and physical activity in 3 groups of people:
- 51 529 male health professionals (aged 40-75) from the Health Professionals Follow-Up Study
- 121 700 nurses (aged 35-55) from the Nurses’ Health Study (NHS)
- 116 686 nurses (aged 24-44) from the Nurses’ Health Study II (NHS II)
Over more than 20 years of monitoring, participants were asked every 4 years to state their weight, and how often over the preceding year they had eaten a serving (28 g or 1 ounce) of nuts, including peanuts and peanut butter. Average weekly exercise-walking, jogging, cycling, swimming, racquet sports, and gardening-was assessed every 2 years by questionnaire.
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Between 1986 and 2010, total nut consumption rose from a quarter to just under half a serving/day in men and from 0.15 to 0.31 servings/day among the women in the NHS study. Between 1991 and 2011, total daily nut consumption rose from 0.07 to 0.31 servings among women in the NHS II study.
Increasing consumption of any type of nut was associated with less long-term weight gain and a lower risk of becoming obese (body mass index of ≥30 kg/m2). Increasing nut consumption by a half serving/day was associated with a lower risk of putting on ≥4 lbs over any 4-year period. A consistently higher nut intake of at least half a serving/day was associated with a 23% lower risk of putting on ≥10 lbs and of becoming obese over the same timeframe.
The researchers suggested multiple mechanisms underlying their observations including:
- Chewing nuts takes some effort which may lead to dietary modification through reduced food intake
- The high-fiber content of nuts can delay stomach emptying and increase satiety
- Nut fiber binds well to fats in the gut
- The high unsaturated fat content of nuts increases resting energy expenditure, which may also help to prevent weight gain