Do Carbs Make You Gain Weight? Here's What a Dietitian Has to Say

One of the biggest nutrition misconceptions is that eating carbohydrates makes you fat. After all, haven't celebrities and influencers been sharing their low-carb weight-loss success stories for years? "Carbs are an easy villain for those touting restrictive diets for weight loss," says Lauren Harris-Pincus, M.S., RDN, founder of NutritionStarringYOU.com and author of The Everything Easy Pre-Diabetes Cookbook. "This is largely because we overeat so many foods that are high in carbs but low in nutrients, like those found in ultra-processed snack foods, desserts and fast food," adds Harris-Pincus.

But, believe it or not, the 2020-2025 Dietary Guidelines for Americans recommends eating 45% to 65% of daily calories from carbs. Although those recommendations may seem high, there's a good reason that you need so many carbs—they provide energy for everyday life. Plus, not all carbs are created equal. Some carb-rich foods are highly nutritious, while others are may not offer much besides calories that burn up quickly.

It's time to set the record straight on carbs, once and for all. Let's chat about the true definition of carbohydrates, whether or not they make you gain weight, and tips for incorporating carbs into a balanced diet.

What Are Carbohydrates?

Carbohydrates are the body's preferred energy source. They help control blood glucose and insulin metabolism, provide fiber, fuel the brain, supply energy for daily activities and exercise and play a role in cholesterol and triglyceride metabolism. Someone following a 2,000-calorie diet should aim for about 900 to 1,300 calories (or 225 to 325 grams) of carbohydrates per day.

There are two types of carbs—simple and complex. Simple carbs have just two sugar molecules, and they are rapidly digested. They are found in foods like honey, sugar, desserts, chips, soda and refined grains. Complex carbs have more sugar molecules and take longer to digest. Plus, they're often paired with fiber and other nutrients that help the body break them down more slowly and have more sustain energy, versus a sharp spike and crash. Foods like grains, beans, legumes, fruits and vegetables contain complex carbohydrates.

"It's really important to differentiate between nutrient-dense whole-food carb sources and those that are ultra-processed and refined," says Harris-Pincus. "Carb-based fiber-rich foods, like fruit, veggies, beans and whole grains, provide essential nutrients as well as antioxidants and phytonutrients that can help to prevent the development of lifestyle diseases, like diabetes, cardiovascular disease and some [types of] cancers," she adds.

Do Carbs Make You Gain Weight?

"Carbohydrates and protein both contain 4 calories per gram, so it's the portion size and type of carb that matters for weight gain," says Harris-Pincus. Weight gain oftentimes is related to consuming more calories than you burn consistently over a long period of time. But, according to Harris-Pincus, the types of food you choose are as important as the number of calories they contain.

"Meals containing foods with protein, fiber and heart-healthy fats are digested and absorbed slowly, which helps to keep you satisfied longer and consume fewer overall calories," says Harris-Pincus. On the other end of the spectrum, ultra-processed foods, like chips and cookies, are hyper-palatable and easy to overeat, so the calories add up very quickly. As a matter of fact, a diet high in ultra-processed foods is associated with an increased risk of obesity and heart disease.

Although carbs are often demonized, science says they aren't the cause of weight gain. A 2022 review of the research found no difference in weight loss when people who were overweight and obese ate either low‐carbohydrate or balanced‐carbohydrate weight‐reducing diets. Another 2022 systematic review in the European Journal of Clinical Nutrition looked at the effectiveness of a low-fat, high-carbohydrate diet as compared to a low-carbohydrate, high-fat diet on weight loss and cardiovascular risk factors. The study authors concluded that both diets effectively helped control weight and reduced cardiovascular risk factors.

The type of carbs you choose makes all the difference in your weight goals. It's important not to completely cut carbs from your diet because they are the body's primary energy source and they are a good source of several vitamins and minerals the body needs to thrive. Dietary carbs are broken down into glucose, a type of sugar that feeds the cells, tissues, organs and brain. Without enough carbs in the diet, the body starts to break down muscle or fat for energy, although the brain can't easily use these fuel sources. In other words, skimping on carbs is an inefficient process for the body and can cause brain fog and lethargy, which could potentially cause you to eat more.

Tips for Incorporating Carbs into a Balanced Diet

"Instead of focusing on what to cut out, create a goal to add more fiber-rich carbs to your diet," says Harris-Pincus. Here are her top tips for doing so:

• Fill half your plate with at least one fruit or veggie per meal.
• Fill the remaining half of your plate with a quarter lean proteins, like chicken, tofu, tempeh, fish or eggs and a quarter whole grains, starchy vegetables or beans.
• Aim to eat 25 to 38 grams of fiber per day.
• Try to limit added sugar intake to less than 10% of daily calories (this is around 25 to 36 grams per day depending on your intake).
• Enjoy some treats as part of an overall balanced diet without fear or guilt.

Frequently Asked Questions

1. Do carbs cause weight gain?

Carbs alone are not the only cause of weight gain. Changes in weight are more nuanced and come down to the types of carbs you eat, total calorie intake and other factors like physical activity, genetics, stress levels and more.

2. Are carbs bad for belly fat?

No one macronutrient is associated with an increase in belly fat. As a matter of fact, fat accumulation happens in different parts of the body. For some people, eating too many high-added-sugar carbs may lead to belly fat. For others, it may lead to weight gain in other parts of the body like around the butt or thighs.

3. Is eating carbs good for losing weight?

Eating the right types of carbs can promote weight loss. A 2019 study in The Journal of Nutrition found that fiber intake may help promote weight loss. Fiber is found in carb-rich foods like fruits, vegetables, beans, legumes and whole grains.

The Bottom Line

Carbs are the body's primary source of energy, and eating them is not the only reason for weight gain or loss. To avoid weight gain, eat plenty of nutritious carb-rich foods, like fruits, vegetables, beans, legumes and whole grains. These foods are rich in fiber, which will help keep you full and prevent overeating. Ultra-processed carbs, like those found in sweets and snacks, are more likely to contribute to weight gain and should be enjoyed less frequently and in moderation.