Are Beans a Protein or a Carb? Should You Limit Them? An Expert Answers

If you are trying to follow a low-carb diet while tracking your macros – the carbs, proteins, and fats that you consume every day – there can be some confusion when it comes to beans, which check more than one box. So we talked to Natalie Rizzo, a New York-based registered dietitian, to answer the question, "Are beans carbs or protein?"

Technically, beans are a starchy vegetable, and they do contain carbs, but beans are so full of protein that most people eating plant-based or trying to get more high-fiber foods into their diet, turn to beans as a great source of protein, fiber, and other important nutrients.

Still, if you worry about the carbs in plant-based proteins like beans or other vegetables, you are not alone. After all, beans and legumes are quite starchy and if you are trying to follow a low-carb diet, the carbs in beans can add up. I hear from my clients that they are constantly worried that carbs make you gain weight. That's not exactly the case. Let me set the record straight.

Balancing carbs and protein on a plant-based diet may seem like an impossible task. But not all carbs are created equal, so I tell people that they really shouldn't worry too much about the carb content of the foods they are eating on a whole food plant-based diet. Here’s why.

In the nutrition world, the claim that eating carbs make you fat is one of the biggest misconceptions around. Fruits, vegetables, whole grains, beans, and legumes all fall into the carb category, along with soda, desserts, chips, pretzels, and other processed foods.

Distinguishing the healthy from the not-so-healthy carbs is one of the keys to figuring out how to eat right on a plant-based diet. Whereas whole food carbs provide beneficial vitamins, minerals, fiber, and antioxidants to the diet, processed refined carbs often lack nutrients, which get stripped out in processing. It’s well known that eating an ultra-processed diet is associated with an increased risk of obesity and heart disease, making choosing the right type of carbs key to a healthy diet.

The Dietary Guidelines for Americans recommend that 45 to 65 percent of your total daily calories come from carbohydrates. In other words, the majority of your diet should consist of carbs. This translates to about 3 to 5 grams per kilogram (1.3 to 2.2 grams per pound) of body weight per day. For a 150-pound individual, that’s about 195 to 330 grams of carbs each day.

The number of daily carbs a person needs varies greatly based on activity level, with active people needing more. Since carbs are the primary fuel for exercise, those who engage in regular endurance activity may need anywhere from 5 to 10 grams of carbs per kilogram (2.2 to 4.5 grams per pound) of body weight per day. For that same 150-pound person, that equals 330 to 675 grams of carbs each day.

Why is the recommendation for carbs so high? Well, this macronutrient plays an important role in maintaining energy levels for daily life and exercise and fueling the brain and other organs. What’s more, eating a diet rich in fruits and vegetables (aka carbs) can help reduce the risk of many chronic diseases, like cardiovascular disease, type 2 diabetes, cancer, and obesity. Despite these benefits, only 9 percent of adults eat the recommended amount of vegetables and 12 percent of adults eat the recommended amount of fruit, according to CDC analysis.

When you look at the carb count on beans, lentils, or brown rice, you may feel like you exceed the recommended percentage of daily carbs. This is because these legumes –– as well as the carbs in vegetables and whole grains –– are "complex" carbs rather than simple carbs, and have long molecule chains which give your body vitamins, minerals, and fiber as well as energy.

After all, 100 grams of lentils has 9 grams of protein and 20 grams of carbs, as compared to 32 grams of protein and zero grams of carbs in 100 grams of chicken. If you’re eating a wide variety of fruits, vegetables, beans, legumes, soy products, nuts, and seeds, chances are that your daily carb count falls within 45-65 percent of calories. And research suggests that it may not matter even if it goes beyond that “ideal” range.

A recent study in the journal Nature Medicine placed 20 participants on either an animal-based diet with 10 percent carbs and 75 percent fat or a plant-based diet with 75 percent carbs and 10 percent fat. Both groups consumed 5 percent of calories from protein, and neither restricted calories. Although the higher-carb plant-based eaters experienced higher insulin spikes after eating, they ate fewer total calories and lost more body fat than the low-carb eaters. Although this study was small in size, the results are promising and warrant further investigation.

An animal study used 29 different types of diets to test the carbohydrate-insulin model, a theory that suggests that insulin spikes occurring after eating carbs increase calorie intake and decrease energy expenditure, leading to weight gain. Like the people in the previous study, after three months, the mice on the higher-carb diets actually ate fewer calories, gained less fat, and had lower body weight. Lastly, a recent review of current research found that a high-carbohydrate diet or increased percentage of total energy intake in the form of carbohydrates does not increase the odds of obesity.

When eating a plant-based diet don't worry about the carbs in beans and other legumes since, vegetables, fruit, and other whole foods contain fiber that can slow down nutrient absorption and keep you feeling full longer, and prevent insulin spikes.

Of course, eating too much of any macronutrient can cause weight gain. If you constantly consume more calories than you burn off, the body stores those calories as fat.

This can happen when the excess calories are carbs, protein, or fat. Plant-based diets are associated with lower body mass index (BMI), so don’t worry about carb counting if you’re eating a primarily whole-food, plant-based diet.

For more research-backed content, visit The Beet's Health & Nutrition articles.