Don’t knock nuts. While they have a bad rap for being high in calories, these nutritional powerhouses could be a dieter’s best friend – as long as you don’t overdo it. Nuts often get lumped into the “bad” food category, especially for those worried about weight gain. Given that nuts are high in fat and are calorie-dense, that makes sense. After all, if you add nuts to your diet when you’re trying to lose weight, isn’t that counterproductive?

The simple answer is no, nuts actually help you lose weight or maintain a healthy weight, says Richard D. Mattes, M.P.H., Ph.D., RD, distinguished professor of nutrition science at Purdue University in West Lafayette, Indiana. “The reality is that in spite of nuts being high-fat and energy-dense, they have a number of properties that mitigate this,” he explains. So while eating nuts won’t help you lose weight, they add protein, fiber, nutrients, and satiating healthy fat to your diet, helpful if you’re trying to restrict intake over the course of a day.

Why Nuts Won't Make You Gain Weight

Nuts, which include ground nuts like peanuts and tree nuts like almonds, pistachios, walnuts, pecans, and cashews, and others, do deliver the calories. Just one ounce of walnuts contains 190 calories, while the same amount of cashews, pistachios, and almonds contain 160 calories. The fat content is also high: 19 grams in walnuts, 14 grams in almonds, and 13 grams in pistachios and cashews. But they are also an excellent source of protein. Peanuts have 9./5 grams of protein per 1/4 cup (a typical serving). Almonds have 7 grams per 1/4 cup, while pistachios have 6 grams of protein per 1/4 cup, cashews have 5 grams per 1.4 cup and pine nuts contain 4.5 grams of protein per 1/4 cup.

But numbers don’t always tell the whole story, as is the case here. That’s because no matter what nut you choose, they each have unique properties that help negate these effects. For starters, you don’t absorb all of the energy (aka calories) from nuts. “There’s a portion of the energy that’s not biologically available,” Mattes says, so your body absorbs only about 80 percent of the calories from nuts. Unused calories exit through your stool.

Take a look at data from the Agricultural Research Service in which researchers examined how many of the calories in walnuts, almonds, and pistachios the body uses versus how many are actually in these nuts. Across the board, the body used fewer calories than were actually in the nuts. For pistachios, calorie uptake was 22.6 calories per gram versus 23.7 calories per gram, the generally accepted number of calories in pistachios. So in that ounce of pistachios, your body would only use 153.8 of the 161.9 calories available. And in one ounce of walnuts, 146 of the 185 calories were available to the body while in almonds, the difference was 129 calories versus roughly 170 calories.

Plus, because nuts are so satiating, they reduce how much you eat that day. “When people eat nuts, they tend to compensate by eating less during others times of the day and offsetting a good portion of the energy,” Mattes says. His research shows that nuts may even make an energy-restricted diet more palatable, which could improve compliance to that diet.

What else you should love about nuts? “Although this is less established, nuts can elevate resting energy expenditure, which would also contribute to offsetting the calories,” Mattes says.

All of this means nuts can be a dieter’s best friend, and there are numerous studies to show that nuts can help stave off weight gain. For instance, according to a study from BMJ Nutrition, Prevention & Health, increasing nut consumption by a serving a day was significantly associated with less weight gain and lower risk for obesity over a four-year period, even more so when study participants swapped a serving of any type of nuts for less healthy foods like French fries, dessert, red or processed meat or potato chips.

Just note that this doesn’t apply to nut butters. “When you consume a nut butter, the cell wall of the nut has been broken, which liberates the energy contained in those cells,” Mattes says. In other words, your body will absorb all of the calories in those nut butters.

The Health Benefits of Nuts

Weight management isn’t the only reason nuts deserve a spot in your plant-based diet. “Nuts contain healthy fats and are a great source of dietary fiber that feeds the gut microbiome,” says William W. Li, M.D., an internationally renowned physician, scientist and author of the New York Times bestseller Eat to Beat Disease. That can lower blood cholesterol and has even been shown to activate fat-burning processes in the body.

Along with containing monounsaturated fats, fiber, and protein, nuts are also loaded with micronutrients, says Alexandra Caspero, M.A., R.D., a dietitian in St. Louis who runs delishknowledge.com and co-author of The Plant-Based Baby + Toddler. Think vitamin E, magnesium, phosphorus, copper, manganese, and selenium.

Nuts have been shown to help lower the risk of heart disease.  “In three large prospective cohort studies, higher consumption of nuts was inversely associated with total cardiovascular disease risk and coronary heart disease risk,” Caspero says. “And it’s not just heart disease, as significant inverse associations were also observed between nut consumption and deaths due to cancer and respiratory disease.”

The key to eating nuts is practicing moderation. They may be good for you, but those calories and fat can add up. Generally about an ounce or an ounce and a half per day is the sweet spot, Mattes says.

Just make sure you choose plain nuts. Many are fried or coated in sugar or contain added preservatives. “All of this can reduce the health potential of tree nuts,” Li says.

Bottom line: “Nuts should be included in the diet, in moderation, without a concern for weight gain,” Caspero says.