Increasing Daily Nut Consumption May Help Stave Off Gradual Weight Gain, Reduce Obesity Risk

Increasing nut consumption by just half a serving (14 g) a day may help mitigate the gradual weight gain common during adulthood, and beneficially contribute to the prevention of obesity, according to a new study in the journal BMJ Nutrition, Prevention Health.

Increasing daily consumption of nuts is associated with less long-term weight gain and a lower risk of obesity in adults. Image credit: Piviso.

Nuts are nutrient-dense foods rich in unsaturated fatty acids, vitamins, minerals and fiber. Their high fat content leads some to perceive nuts as unhealthful and to be avoided by those attempting to manage or lose their body weight.

Consumption of nuts and seeds in the U.S. increased from 0.5 servings/day in 1999 to 0.75 servings/day in 2012.

A research team led by Dr. Deirdre Tobias of the Harvard University T.H. Chan School of Public Health aimed to evaluate the association between changes in total consumption of nuts and intakes of different nuts (including peanuts) and long-term weight change, in three independent cohort studies.

They analysed information on weight, diet and physical activity in 51,529 male health professionals (40-75 years old) from the Health Professionals Follow Up Study; 121,700 nurses (35-55 years old) from the Nurses Health Study (NHS); and 116,686 nurses (24-44 years old) 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) of nuts, including peanuts and peanut butter.

Average weekly exercise — walking, jogging, cycling, swimming, racquet sports and gardening — was assessed every two years by questionnaire. It was measured in metabolic equivalent of task hours, which express how much energy (calories) is expended per hour of physical activity.

Average annual weight gain across all three groups was 0.32 kg.

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 (BMI of 30 or more kg/m2), overall.

Increasing nut consumption by half a serving a day was associated with a lower risk of putting on 2 kg or more over any 4 year period. And a daily half serving increase in walnut consumption was associated with a 15% lower risk of obesity.

Substituting processed meats, refined grains, or desserts, including chocolates, pastries, pies and donuts, for half a serving of nuts was associated with staving off weight gain of between 0.41 and 0.70 kg in any 4 year period.

Within any 4 year period, upping daily nut consumption from none to at least half a serving was associated with staving off 0.74 kg in weight, a lower risk of moderate weight gain, and a 16% lower risk of obesity, compared with not eating any nuts.

And a consistently higher nut intake of at least half a serving a day was associated with a 23% lower risk of putting on 5 kg or more and of becoming obese over the same timeframe. No such associations were observed for increases in peanut butter intake.

“Our findings support food-based dietary recommendations and support the incorporation of nuts as an effective strategy for making attainable dietary modifications for the primary prevention of obesity,” Dr. Tobias and colleagues said.

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X. Liu et al. 2019. Changes in nut consumption influence long-term weight change in US men and women. BMJ Nutrition, Prevention Health, published online September 23, 2019; doi: 10.1136/bmjnph-2019-000034