Eating a Handful of Nuts a Day May Help With Weight Control, Study Finds
Researchers at Harvard University found that eating a handful of nuts may help with weight loss and maintenance.
Nuts, whether you add a handful a day to your regular diet or swap them for your daily bag of potato chips and have nuts instead, may help you maintain your weight or drop unwanted pounds, according to a preliminary study. While nuts are calorie dense, researchers sought to analyze whether they affected long-term weight change in the research, which will be presented November 10, 2018, at the American Heart Association’s Scientific Sessions 2018 in Chicago.
“For someone interested in weight management or weight loss, quite often the tendency is to shy away from calorie-dense foods,” says the study's first author, Xiaoran Liu, PhD, a research associate in the nutrition department of the Harvard School of Public Health in Boston.
The researchers looked at the effects of adding nuts to participants’ diets and swapping nuts for other snacks, including red meat, processed meat, fries, desserts, and chips. In both cases, a serving of nuts was beneficial. Adding a daily serving (about 28 grams, or a small handful) was associated with less risk of weight gain or becoming obese. And substituting a food with a daily serving of nuts was associated with less weight gain.
For their analysis, Dr. Liu and her colleagues followed three separate study cohorts: 25,394 men (Health Professionals Follow-up Study), 53,541 women (Nurses’ Health Study), and 47,255 women (Nurses’ Health Study II). The participants did not have chronic disease and were not obese at the start of the study. To determine the amount of nuts that the participants ate, researchers used food-frequency questionnaires every four years over the course of each established study group, which ran for an average of 26 years. Researchers found that walnuts were especially effective, though it’s worth noting the California Walnut Commission partially funded the study.
The study participants were mainly white, but Liu notes that she expects results would be consistent across other populations, as the association between nut consumption and other health outcomes is “pretty consistent” across populations in the U.S. and Europe.
The fiber in nuts may explain the researchers’ findings, as this nutrient is important for weight control, says Lori Chong, RD, at the Ohio State University Wexner Medical Center in Columbus, who wasn’t involved in the current study. It could also be related to the blood sugar response to nuts, compared with the other snacks. “Anything that spikes blood sugar will spike insulin, and that promotes fat storage,” Chong says. “If you snack on something that doesn’t cause that blood sugar spike, it doesn’t require insulin.”
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Nuts May Help With Weight Maintenance Along With Weight Loss
For optimal health, maintaining your weight is just as, if not more, important than losing weight if you need to, experts say. And, as the study suggests, nuts may help with weight maintenance.
“When people enter adulthood, over time they have a gradual weight gain of [about] 1 pound a year [on average],” Liu says. “That extra 10 pounds after about 15 years is associated with health risks such as cancer and type 2 diabetes.”
Preventing weight gain is a more effective strategy than trying to lose weight later, Chong agrees.
“A lot of people feel it’s normal or expected to gain weight as you get older, but it doesn’t have to happen,” Chong says. “We should just be focusing on a good, healthy balance in our diet, staying away from processed foods, and getting regular exercise.”
Nuts Are Calorie-Dense but Full of Nutrients
Liu notes that her team’s findings showed calories are not the only marker of a food’s nutritional impact. Nuts are high in healthy polyunsaturated fat and monounsaturated fat, which are heart healthy especially when they're replacing unhealthy saturated and trans fat. The fiber in nuts improves satiety and fullness and is beneficial for gut microbial diversity, Liu says. Gut bacteria may play a role in immunity, weight, and risk for various diseases such as diabetes, heart disease, and inflammatory bowel diseases, according to an April 2015 article in the International Journal of Molecular Sciences.
In addition, nuts provide all three macronutrients (carbohydrates, protein, fat), and are a good source of calcium, phytonutrients, and other minerals your body needs for optimal health.
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Brazil Nuts Can Help You Feel Full, a Separate Study Suggests
Other recent research supports eating nuts for weight control.
In an unrelated preliminary study from San Diego State University also presented at the American Heart Association’s Scientific Sessions, researchers compared the effects of Brazil nuts and pretzels on satiety. The small study of 22 adults found that, after eating Brazil nuts, participants felt fuller and had stable blood glucose and insulin levels 40 minutes after eating. Forty minutes after having pretzels, participants showed a significant increase in blood glucose and insulin.
Rather than focus on finding the most nutrient dense or “best” nut, Chong recommends eating a variety to get a breadth of nutrients.
“There will always be a slight nutritional difference from one variety to another,” she says.
What to Look for When Buying Nuts at the Grocery Store
When it comes to grocery shopping for nuts, Chong recommends buying raw or dry-roasted nuts. Skip those roasted in oil, topped with salt, and any that have added sweeteners (we’re looking at you, honey roasted).
“Most Americans are consuming way too much sugar, and that’s just another example of extra sugar we don’t need,” Chong says.
Chong avoids nuts that have added spices, as they may include chemicals used to create flavor. If you don’t like plain, raw nuts, roast them at home and mix them with your favorite herbs or spices for flavor.
Chong likes Trader Joe’s or Aldi’s as options for well-priced nuts — plus, they sell a lot that are raw or dry roasted.
“Don’t buy a Snickers bar to try to get your nuts,” Chong says.