Gain less weight by snacking on nuts

Researchers affiliated with Harvard's Medical School utilized data gathered through three large-scale, long-term observational studies: the Health Professionals' Follow-up Study and the Nurses' Health Study, both of which began recruiting participants in 1986, and the Nurses' Health Study II, which began recruiting participants in 1991.

Upon enrollment and every 4 years thereafter, the participants in these studies responded to detailed dietary, health, and demographic questionnaires, which allowed the authors to not just estimate each participant's daily intake of nuts, but also to track how the participant's nut intake changed over time as well as how that participant's Body Mass Index might have changed over the same time periods, up to 2011, the point at which the authors closed their analysis.

The authors excluded from their study any participant who, at the start of the studies, reporting experiencing cancer, diabetes (regardless of type), heart attack or stroke, as well as those with missing or implausible BMI scores or dietary questionnaires.

As well, the authors removed from further analysis the responses of any participant who reached the age of 65 - to avoid the effects of age-related weight or muscle loss.

The final number of participants in these researchers' analysis included over 144,000 people, of whom the vast majority were Caucasian women.

The authors note that the amount of weight gain per year, averaged across the three study groups, was about 3/4 pound per year, with women averaging a greater yearly weight gain than men.

In their analysis, the researchers controlled for age, Body Mass Index, smoking status, physical activity, and a number of dietary factors, from the total number of calories, the amount of vegetables consumed, and even the amount of French fries consumed, while correlating nut intake across each four-year period with each participant's Body Mass Index (and whether it changed in that four-year period).

The findings? Adding just 1/2 serving of nuts (any type of nuts) per day, on average, to one's daily intake meant gaining 1/2 pound less over 4 years. Add another 1/2 serving of walnuts, specifically, each day reduced one's weight gain by 0.8 pounds, and another 1/2 cup of tree nuts in general reduced one's weight gain by just a little less.

Indeed, compared with those who didn't eat nuts much at all, those who ate just 1/2 serving of nuts per day were 23% less likely to move into the clinically obese range of Body Mass Index.

This analysis defined 'nuts' as including peanuts and peanut butter along with tree nuts. As the authors themselves sum up: "Increasing total nut intake by 0.5 servings/day was associated with less weight gain... suggesting that incorporating nuts into the diet, even given their calorie content, is helpful in mitigating a portion of long-term gradual weight gain."

What this means for you

If you're going to snack, have nuts. raw nuts would be best, with dry roasted and unsalted next, then dry roasted and lightly salted followed by dry roasted and salted. Chocolate- or candy-coated nuts should be considered candy and saved for a special treat (as in, once every few months).

The Mediterranean-style diet guideline of 8 ounces of nuts per day can easily be achieved by having just 1/2 ounce of nuts for your between-meal snacks. They'll be tasty and satisfying!

First posted: October 2, 2019