Co-written by Meredith Price, MS, RD, CDN & Jaclyn Korman, PNW Intern, Summer 2020
Have you ever heard that carbohydrates, i.e. carbs, are bad for you or that they cause weight gain? If this is true, how does it play out on a plant-based diet? Many healthy, plant-based foods are considered carbohydrates including grains (like bread and quinoa), fruits, starchy vegetables, and legumes (such as beans and lentils). I recently had someone ask if transitioning to a plant-based diet would make her gain weight because of “all the carbs”. With the myths surrounding carbohydrates in general, particularly when we’re discussing a plant-based diet, there’s a lot to explore and bring to light.
A “Normal” Amount of Carbohydrates
Despite all of the (unfounded) beliefs, carbohydrates are really important for us to include in our diet and in large amounts. This macronutrient is a key part of our food intake and most of us should be getting 45-65% of our calories from carbs, no matter if we’re plant-based or not. What does this mean in reality? That about half of the foods we eat should be considered a carb. For example, if someone is following a 2,000 calorie diet, about 1,000 of those calories, or 250g of carbs, should be contributed by carbohydrates.
Carbohydrates 101
Why do we need carbohydrates? The number one reason is that our body relies on them as its main source of energy. For you science nerds out there, when the body digests and absorbs carbohydrates, they enter the bloodstream as glucose which cells use as energy to do our everyday routines such as breathing, thinking, walking, etc. as well as more vigorous activities like exercise.
Additionally, sources of carbohydrates, like whole grains, fruits, and legumes, contribute many important nutrients to a plant-based diet. These include fiber, phytonutrients, antioxidants, protein, vitamins, and minerals. Can you imagine a plant-based diet lacking in quinoa, oranges, oats, sweet potatoes, bananas, lentils, edamame, black beans, chickpeas or rice? All of those examples are considered to be “high carb” foods.
Sugar vs Fiber
To be fair, not all carbohydrates are created equal. Aside from the healthy examples listed above, sugar is also a form of a carb. The sugar naturally found in fruit, called fructose, is a healthy choice. But, table sugar, maple syrup, agave, and other sweeteners are not something to rely on as energy. So yes, if you ate half of your calories in the form of cookies, cakes, and pancakes with maple syrup, you might gain weight. Not because those foods contain carbohydrates but rather because they’re high calorie and not providing a whole lot of other beneficial nutrients. I’m not saying this to demonize these foods or suggest that you shouldn’t ever have them (if you know me, you know that I’m a chocoholic) but I want to make it clear that the term “carbohydrate” does not mean one thing.
On the other hand, fiber, which is only naturally found in carbohydrate-rich foods, is one of the best parts about eating a diet rich in carbohydrates. Why? Because fiber slows down digestion and keeps us feeling satiated after a meal. Fiber also has amazing benefits such as that it helps prevent constipation, keeps our digestive tract regular, promotes a healthy gut, stabilizes our blood sugar and can help lower cholesterol. Foods like fruits, nuts, beans, whole grains, and veggies are packed with fiber. Since fiber helps us feel more full and satisfied, we’re less likely to overeat. Therefore, individuals who consume a higher fiber diet, i.e. a plant-based diet, tend to maintain a healthy weight status, not gain weight.
“Low” vs “High” Carb & Weight Gain
There are many benefits from eating plant-based including a lower risk of heart disease and other chronic diseases. Additionally, studies consistently show that individuals who adhere to a plant-based style of eating tend to have a healthier weight status compared to omnivores. Studies have also shown more weight loss on a plant-based diet, even when placed on a “high-carb” version such as upwards of 78% of calories from carbs. It’s important to note that there are varying definitions of what exactly “high carb” means. Some studies consider over 65% of calories coming from carbs to be “high” while some surprisingly consider it to be over 45%, which is strange considering that’s within the recommended guidelines.
Alternatively, a “low-carb” diet, which seems to range from 20-70 grams a day (or 4-14% of calories), does tend to result in weight loss, at least in the first few weeks of following this type of restriction. It’s important to note that the weight loss seen in the beginning is generally water weight. After a few months of carbohydrate restriction, most individuals gain back the lost weight. Other dangerous and/or negative side effects often occur when going low-carb such as nausea, dizziness, constipation, dehydration, bad breath, and loss of appetite.
Plant-Based vs Omnivore
When comparing omnivore and plant-based style diets, the carbohydrate intake amounts are usually very similar (see table below) and both fall within the range of the recommended amounts. Therefore, it’s generally a myth that a plant-based diet is much higher in carbs. However, what is true is that fiber intake tends to be higher on a plant-based diet, which is likely why we actually tend to see weight loss when individuals transition to a plant-based diet.
Source: Clarys, Peter et al. “Comparison of nutritional quality of the vegan, vegetarian, semi-vegetarian, pesco-vegetarian and omnivorous diet.” Nutrients vol. 6,3 1318-32. 24 Mar. 2014, doi:10.3390/nu6031318
Important note about this study is that it was done in Belgium. An American version would likely be much lower in fiber, particularly on the omnivore diet.
Bottom Line
To sum it up, the last thing you should worry about when starting a plant-based diet is the carbs. Carbohydrates are important to consume because they provide us with our main source of energy, optimal nutrients, and fiber. There is no evidence that carbs make you gain weight and according to research, they can actually help with weight management and assist to achieve a healthy lifestyle.
