Just a handful of nuts may help keep us from packing on the pounds as we age

Eating a handful of almonds, walnuts, peanuts or any type of nut on a regular basis may help prevent excessive weight gain and even lower the risk of obesity, new research suggests.

It may be that substituting healthy nuts for unhealthy snacks is a simple strategy to ward off the gradual weight gain that often accompanies aging, according to the researchers. Nuts also help us feel full longer, which might offset cravings for junk food.

Researchers looked at the diet and weight of more than 280,000 adults taking part in three long-term research studies. Over more than 20 years of monitoring, participants were asked every four years about their weight and, among other things, how often, over the preceding year, they had eaten a serving (about one ounce) of nuts.

On average, U.S. adults put on one pound of weight every year, according to researcher and epidemiologist Deirdre Tobias, a co-author of the new study, which appears in the online journal BMJ Nutrition, Prevention & Health. "We wanted to know whether nuts were associated with long-term weight gain," says Tobias, who's with Brigham and Women's Hospital in Boston. Tobias and her colleagues hypothesized that nuts might be beneficial, given the association of nuts with a lower risk of heart disease and Type 2 diabetes.

The researchers found that making nuts a regular part of one's diet was associated with less long-term weight gain and a lower risk of obesity. The people who most consistently ate nuts gained, on average, about half a pound a year, while those who ate nuts only now and then gained, on average, about one pound each year. That may not sound like a big difference, but Tobias says, "Those half-pounds add up over time."

It's important to note that we're not talking about piles of nuts — just a small handful a day, which Tobias says is about a dozen almonds or maybe 10 walnuts.

In analyzing data about participants' diets, researchers were able to see that as nuts became a more regular part of people's diets, their unhealthy food consumption decreased, including foods such as processed meats, refined grains and desserts like chocolates, pastries, pies and doughnuts.

"When you increase nuts at the expense of these other snack foods, there's an even greater benefit," says Tobias. A consistent nut intake of at least a half-ounce a day was associated with a 23 percent lower risk of putting on 10 or more pounds or of becoming obese over a four-year period.

But nuts' role in weight maintenance goes beyond merely acting as a substitute for pastries. "Nuts have protein in them, which helps us feel full longer, and fiber, which helps fill us up," says Libby Mills, spokesperson for the Academy of Nutrition and Dietetics. And because nuts are high in healthy fat, Mills says, they take much longer to digest than carbs and protein, and that can also "make us feel full longer."

As a registered dietitian, Mills says most of her clients are seeking to lose weight. They "love nuts," she says, so for them, the findings are welcome news. "They find them an easy, convenient snack to keep at their desk, perhaps individually packaged, tucked into a purse or gym bag, so they're always super-handy and perfect for people on the go."

So next time you find yourself craving something between meals, the take-home message here is clear: Go for the nuts — not the cookies.

And here's an added benefit: A nut habit is good for the planet, say the researchers. "In addition to the impact on human health, using environmentally friendly plant-based protein, such as nuts and seeds, to replace animal sources of protein may contribute to the promotion of a global sustainable food system," they write.

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