What Low Carb Actually Means
Depending on who you talk to, there are different definitions of a low-carb diet. Plans can range from 100 grams of carbohydrates per day to zero grams (yikes), says Susan Kleiner, PhD, RD, author of Power Eating. To put that into perspective, a small piece of fruit has about 15 grams of carbs and a banana contains up to 30 grams.
For the sake of this article, though, we'll define a low-carb diet as containing 100 grams of carbs per day for someone who exercises three times a week at a moderate pace. For everyone else, a true low-carb diet would be about 50 grams per day, says Kleiner.
What's Considered a Carb?
Unfortunately for Regina George, butter is not a carb. But according to the USDA's Nutrient Database, lots of foods, including fruits and veggies, contain high amounts of carbohydrates. Though you probably know that potatoes and bananas are packed with carbohydrates, over 20 grams of the macronutrient are also found in a serving of grapes, apples, pears, or cauliflower. Plus, dried fruits, such as apricots, cranberries, and raisins, have a whopping 80 grams per serving.
You'll find carbs lurking in other unsuspecting places, too. Frozen yogurt, almond and soy milk, barbeque sauce, and protein-packed beans and legumes (including chickpeas, kidney beans, and baked beans) are all considered high-carb foods.
How Low-Carb Diets Became Trendy
According to a 2008 article in the journal Epilepsia, the ketogenic diet, a high-fat, high-protein, low-carb diet, originated as a cure for epilepsy in 500 B.C. and is still used as such today.
The Atkins diet was invented in 1972 as a result of research aimed to help overweight people with hypertension, says Kleiner. Prior to Atkins, doctors were "starving" diseases in overweight patients with ultra-low-calorie diets (500 to 600 calories a day). So when researchers discovered that a high-protein, low-carb diet was just as effective for weight loss, they started using this method so participants could have a normal calorie intake.
The reason these diets have such staying power is because they do help people lose weight, says Keri Gans, RD, author of The Small Change Diet. The thing is, people get frustrated with deprivation diets so they give up, she says.
Why Low-Carb Works Well for Some
No carbs means no-brainer portion control. Weight loss associated with a low-carb diet is mainly a result of eating less, says Albert Matheny, CSCS, RD, of SoHo Strength Lab and Promix Nutrition. "Carbs aren't bad, they're just overconsumed relative to a person's activity level," he says. When you cut carbs, you're giving up the foods you might be overindulging in, which saves you tons of calories.
And it's easy to see why we can't stop, won't stop with the refined carbohydrates, says Matheny. Besides being super-satisfying, things like cereal, spaghetti, and rice are cheaper, more convenient, and more frequently advertised than other foods, he says.
Plus, portion control is difficult for most people. "It's much easier to eliminate a food group than to learn how to eat it in a healthier way," says Gans. If you're a carb overeater, you'll likely be cutting at least 20% of the food you consume, so of course you'd lose weight.
It keeps blood sugar in check. A high-carb diet leads to greater variations in blood sugar, says Matheny. These fluctuations make your body physiologically dependent on carbs, so you crave more and more each time your blood sugar drops. This leads to overeating and weight gain, he says. When you lower your carb intake, your blood sugar stabilizes, and your cravings are crushed.
More carbs = more water weight. Most of the weight you lose when you start a low-carb diet is water weight, says Gans. Fluctuating insulin levels found in many overweight individuals cause the body to retain sodium and water. And, according to a study published in the Journal of the American Heart Association, a high-fat, low-carb diet stabilizes insulin levels, which leads to losing water weight and fat.
Why Low-Carb Doesn't Work for Everyone
You overconsume other macronutrients. Because cutting out a chunk of your food intake leaves you hungry, many people will overeat other macronutrients that they're "allowed" to have, says Matheny. The problem is, if you're consuming 3,000 calories of fat and protein a day and burning only 1,500 calories, you're still going to gain weight—regardless of the carb deficit.
It isn't sustainable. The chief problem with a low-carb diet is that people can't keep it up long-term. Both Kleiner and Gans agree that cutting out carbs completely, or even cutting back to 100 grams a day, is too difficult for most people.
"Giving up a food you love to eat almost always leads to feelings of deprivation," says Kleiner. "If you feel deprived, there is no way you are going to keep up those eating habits."
Your genes love carbs. You may be thinking, "But my sister-in-law's cousin hasn't had bread in 3 years and swears by it!" But, Kleiner says, those who claim they worship at the low-carb altar for the long haul are either lying or genetically predisposed to not miss carbs. It's true; studies have shown that genes can actually affect our taste preferences. And some people's genetically predetermined taste buds might lead them to feel 'meh' about carbs, says Kleiner.
Your body could respond poorly. If you eliminate carbohydrates, especially fiber-packed ones like potatoes, quinoa, and fruit, you're going to experience bloating and constipation from ousting them. Additionally, you could experience vitamin deficiencies and ketosis (a buildup of ketones in the body), which can lead to dehydration and insulin deficiency, says Gans.
It starts to affect your personality. Since carbs are energy fuel, you'll probably feel a bit sluggish, says Gans. And if you really love the starchy stuff, eliminating your favorite foods will make you cranky as hell (in addition to not being able to poop).
What Girls Who Work Out Need to Know
While low-intensity exercises, such as walking and yoga, take less energy and can be sustained without carbs, high-intensity workouts, like cycling and boot camp classes, require more fuel and are tough to take on without the help of carbohydrates in your diet, says Kleiner.
"Carbs are fuel for high-intensity activity," says Matheny.
Your body on a high-intensity sweat sesh and low-carb diet:Taking a high-intensity interval-training class while you're on a low-carb diet is a one-way ticket to the struggle bus. It's highly likely that you'll feel like your effort is at a 10 when you're only at a six, says Kleiner. That's because high-intensity workouts require energy from glucose (which comes from carbs) stored in our muscles, says Matheny. When you run out of glucose fuel, these workouts begin to break down muscle, which is bad for your body and your metabolism.
Also, if you're just starting a low-carb diet, your blood sugar will drop as your muscles become active, which can lead to fatigue and dizziness, says Matheny.
Your body on a low-intensity workout and low-carb meal plan:Since low-intensity workouts don't require as much immediate energy, your body has more time to convert fat to fuel, says Matheny.
Low-carb can lead to more effective fat-burning. That being said, a study published in the journal Metabolism found that ultra-marathoners (people who run 50 to 100 miles at once) experienced higher rates of fat burning when they capped carb consumption at 10% of their diet (for someone who eats 2,000 calories a day, that's 200 calories from carbohydrates, or about two slices of bread). But since the study didn't measure actual performance, we don't know if the runners'workouts were their best or not.
Is Low-Carb Right for You?
Whether you should increase or decrease your carb intake depends on your personal goals, health, and lifestyle.
If you want to lose weight… Nutritionists and scientists agree that a low-carb, ketogenic diet can be helpful for weight loss if used as a short-term solution or jumping-off point. The problem with diets like Atkins is that they force you to make extreme and sudden lifestyle changes. That drastic change often leads to weight loss, much of which is from water weight. And when you start to return to a "balanced" diet, maintaining that weight loss becomes difficult. Plus, yo-yo dieting in this way can have serious consequences for your body and your relationship with food.
If you have health concerns… Both Matheny and Gans point out that if you're diabetic or hypoglycemic, low-carb eating could be useful in blood sugar control, but you should consult a registered dietitian before making any changes. If you have gastrointestinal problems, the lack of fiber might be an issue.
If you have #FitnessGoals… Unless you're sticking to low-intensity yoga, a low-carb diet isn't the best option. High-intensity interval training is one of the most effective training techniques out there, and it requires a ton of carb-fueled energy. If you want to get better, faster, stronger (à la Kanye West), go ahead and eat a sweet potato a few hours before your HIIT workout.
What Is the Best Low-Carb Diet to Follow?
Let's get something out of the way right now: Following a strictly Paleodiet or obsessing over how many grams of carbs you eat per day is a recipe for weight loss failure (not to mention an effed-up relationship with food). Instead, it's best to focus on the types of carbs you're eating, says Gans.
"A healthy diet plan should include whole grains, fruit, veggies, and legumes—all of which are high-fiber carbohydrates," says Gans. We've said it once, we'll say it again: High-fiber foods can improve your digestion and help you lose weight by making you feel fuller, longer. "Learning portion control is key." Your dinner plate should be 25% protein, 25% high-fiber carbohydrates, and 50% vegetables, says Gans.
It's fine to nix refined sugar and carbs (see: rainbow bagels, Lucky Charms, chips, and pasta) if you're looking to cut back for a special event or as a general lifestyle change, says Kleiner. But as Matheny points out, even refined carbs have their place if you've got an activity level that can take it. Consuming refined carbs before you work out can provide quick energy and can even improve your results.
Bottom line: "Healthy eating shouldn't be about deprivation," says Gans.
