Is cutting down on carbohydrates the key to losing weight and improving your health? Advocates of popular diet plans such as Atkins and keto cast most carbs as the enemy when we are hoping to slim down—but a growing body of evidence seems to undermine this theory. Example: A year-long study by Stanford University researchers involving more than 600 overweight adults found that a low-carb diet did not produce greater weight loss than a low-fat diet. A low-carb diet is sometimes defined as less than 130 grams of carbs per day or less than 10% of calories from carbs.
Worse, there’s reason to fear that following a low-carb diet is dangerous. A study in The Lancet Public Health by researchers at Boston’s Brigham and Women’s Hospital found that people who followed low-carb diets had significantly higher mortality rates—that is, they were more likely to die during the 26-year study period, than those who consumed moderate amounts of carbs. A separate study by an international team of researchers at University College London, University of Glasgow and other institutions found that participants who had the lowest carbohydrate intake had the highest rates of fatal cardiovascular disease and cancer, as well as higher mortality rates overall.
Bottom Line Personal asked Rice University dietitian Roberta Anding to share the truth about carbohydrates…
Be wary of any diet that eliminates entire food groups. In the long run, nutritional balance is better for your body than dietary extremism. Rather than avoid specific food groups, select healthier options from within those food groups. Examples: Eat lean proteins such as chicken, fish, tofu and tempeh rather than red meat…and healthy, nutritious carbs like brown rice, sweet potatoes and quinoa rather than white bread. Try to obtain about half your calories from healthy carbs and half from fat and protein. Cover around half of your plate with vegetables or fruits at every meal—they’ll make you feel full sooner so you eat less without feeling deprived.
The secret isn’t to “avoid carbs” or “load up on carbs”—it’s about balance. The popular press tends to turn carbohydrate research into a battle between “avoid carbs” and “consume lots of carbs.” But neither of these extremes is prudent—our bodies need a balanced diet that includes a moderate amount of carbs.
The diets consumed in the “Blue Zones”—areas such as Okinawa, Japan, and Ikaria, Greece, where the locals have some of the world’s longest life expectancies—are neither especially high nor especially low in carbohydrates. And the study in The Lancet Public Health that identified a link between low-carb diets and increased mortality rates did not find that more carbs are always healthier—it found that the lowest mortality rates are among people who obtain 50% to 55% of their calories from high-quality carbs and roughly half from fat and protein.
Potential exception: A low-carb diet could be worth a try for someone who is extremely overweight and has repeatedly tried and failed with other diets. For these people, finding a diet plan that they will follow is of paramount importance, even if that diet itself is less than ideal. But even here, there’s one modification worth making—if the low-carb diet plan selected emphasizes meat consumption, supplement that with significant amounts of vegetables. Reason: Doing so could overcome many of the problems with low-carb diets (more on this below).
Quality matters with carbs, not just quantity. When people picture high-carb foods, they often think of white bread, cereal, pasta, milk and snack foods such as cookies and candy. Cutting these foods out of a diet can indeed contribute to weight loss, along with other health benefits. But not all carbs are created equal—nutritious high-carb foods include sweet potatoes, quinoa, brown rice, legumes, oats and numerous fruits, including mangoes, papayas, apples and bananas. Problem: Low-carb diets tend to push people to avoid all carbohydrates—including these nutritious ones—which deprives the dieter of beneficial antioxidants as well as folic acid and other nutrients. Some people following strict meat-heavy, low-carb diets even have ended up with scurvy, a serious vitamin C deficiency.
Another problem that people can accidentally create for themselves when they follow low-carb diets—they don’t get enough fiber. Nutritious high-carb foods such as beans and whole grains tend to be among the very best sources of dietary fiber. Failing to get sufficient fiber doesn’t just put us at risk for constipation, it has been linked to a range of major health problems including heart disease, stroke, obesity, type 2 diabetes and certain cancers. Dietary fiber also is important for the beneficial bacteria that live in our gut—and failing to feed those bacteria properly can have major health consequences. In fact, the consequences likely are a significant part of the reason why people who follow low-carb diets have shorter life expectancies and elevated risk for a host of health problems.
What’s more, fiber is wonderfully satiating—it makes us feel full much faster than most other foods, reducing the odds that we’ll overeat.
Low-carb diets do sometimes result in some quick weight loss—but that’s deceptive. You may be wondering how diet plans like keto have become so popular if they don’t actually help people lose weight. Well, they do help people lose weight—at first. It’s not unheard of for people to drop five or six pounds within their first few days on the keto diet, convincing them that they’ve finally found an effective weight-loss strategy.
But this initial weight loss is largely water and won’t be sustained. Reason: When you don’t consume carbohydrates, the body starts to consume the carbs stored in our muscles and liver. These carbs are like sponges—each carb molecule holds onto three molecules of water—so the body will ger rid of a noticeable amount of water weight. But these water weight losses will not continue for long.
Another reason low-carb diets sometimes lead to weight loss: When the body is deprived of dietary carbohydrates, the liver produces chemicals known as ketones. It’s these ketones that give the keto diet its name. Elevated ketone levels sometimes make people feel nauseous, and that nausea discourages eating—but making oneself nauseous is certainly not a pleasant way to lose a few pounds.
And like many diets, popular low-carb diets such as keto and Atkins can lead to weight loss simply because they’re extremely restrictive. Some people consume less when given clear-cut rules about which foods they can and cannot eat. For these people, a low-carb diet—or some other restrictive diet—can be an effective way to lose weight. But if you decide to follow a restrictive diet, find a healthful way to fill any nutritional gaps it creates. When using a meat-heavy low-carb diet like Atkins or keto, the best way to fill those gaps is to consume large amounts of vegetables or fruits with each meal.
Your brain and body both crave carbs. There’s a reason why people crave pasta, candy and other high-carb foods when they’re hungry. Carbs are the preferred food of our exercising muscles—fatigue sets in sooner during intensive exercise for people who are on low-carb diets. The brain also prefers to run on carbs—that’s why low-carb diets sometimes leave people feeling irritable or suffering from “brain fog.” An Australian study by the Commonwealth Scientific and Industrial Research Organisation even found that people on low-carb diets experience more symptoms of depression and anxiety.
