While low-carb diets have cycled in and out of fashion, there’s a new wave of enthusiasm for super low-carb diets like the keto diet among celebrities and dieters. But this trend comes at a cost — and perpetuates misconceptions. Here are three facts to understand before jumping on the bread-less bandwagon:
1. Carbohydrates don’t make you fat.
Very low-carb diets are designed to deplete the body of glucose (the primary energy source for your brain and muscles). Without glucose, your body thinks you’re starving and will break fat down into ketone bodies to fuel your brain in a process called ketosis (hence, the keto diet). While fat breakdown via ketosis can produce impressive weight loss, this “quick ?x” can also come at a cost. Doctors warn that starving the brain of its primary energy source could potentially be harmful in the long term.
Are extreme carb-cutting measures really worth it? Probably not. A large randomized clinical trial published earlier this year shows that low-carb diets are no more effective than low-fat diets when it comes to weight loss.
Weight problems are almost never the fault of one food or nutrient — it’s total diet and lifestyle that matter. Calories in any form, be they from carbohydrates, protein or fat, can eventually lead to weight gain if eaten in excess. Plus, all plant foods (from quinoa to carrots) contain some carbohydrates, so people who eat a no-carb or very low-carb diet miss out on great swaths of the plant kingdom with solidly established health benefits.
2. All carbohydrates are not created equal.
It’s true that from kidney beans to candy bars, all carbohydrate foods eventually get broken down into simple sugar molecules like glucose. But different carbohydrate sources can have widely different impacts on health. A simple sugar like what’s found in soda, for example, will quickly spike your blood sugar and won’t deliver any healthy nutrients. On the other hand, a complex carbohydrate like whole-wheat spaghetti has a more gentle impact on your blood sugar and offers many other essential nutrients to boot.
What’s more, eating complex carbs seems to actually help your body burn calories. One study, for instance, showed people burn 50 percent more calories digesting a sandwich on whole-grain bread with real cheese compared to a sandwich on white bread with a processed cheese product, even though both sandwiches had the same number of calories and the same ratio of bread to cheese. Similarly, in a randomized clinical trial of 81 adults, the group eating whole grains had significantly higher concentrations of “good” gut microbes and significantly improved their metabolisms over the six-week study compared with the group eating re?ned grains.
Whole grains, fruits, vegetables, yogurt and beans are all examples of healthy carbohydrate foods. The Dietary Guidelines for Americans recommend filling half your plate with vegetables and fruits, and making at least half of your grains whole grains. (Whole grains contain all of their original bran, germ and endosperm, so contrary to many super low-carb dieters’ beliefs, your body can certainly tell the difference.) Choosing more whole grains is a simple change that can have a big impact on health.
3. Eating carbs is good for the planet — and its inhabitants.
Carbohydrates have anchored traditional diets around the globe for centuries, from rice and millet in Asia to wheat and barley in the Mediterranean. Shifting to a very low-carb diet could have serious consequences for both people and the planet.
In an August 2018 study in The Lancet, for instance, researchers found low-carb diets that had lots of meat were linked with higher mortality rates. Based on data from 15,428 adults, they found that the “sweet spot” for the lowest risk of mortality was eating a diet that has 50 to 55 percent of its calories from carbohydrates, especially from plant foods like whole grains. Similarly, researchers in Canada found that not getting enough whole grains is linked with billions of dollars in healthcare costs.
Shifting diets away from carbohydrates can take a serious toll on the environment as well. Grains provide the most food calories using the least amount of water: only 0.51 liters per calorie (compared with 1.34 liters per calorie of vegetables, 2.09 liters per calorie of fruit and 10.19 liters per calorie of beef). Raising animals for meat production also requires a substantial amount of land. Carbohydrates help us eat lower on the food chain and make the best use of our planet’s precious resources.
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