There’s an equal amount of confusion and hype surrounding a low-carb diet.
Research shows low-carb diets can be an effective way to shed pounds — although not necessarily superior to weight-reduction results achieved by other diets, such as a low-fat or reduced-calorie diets.
But a low-carb diet plan isn’t as straightforward as the name might have you believe.
“A low-carbohydrate diet can have a wide, unclear definition,” says Holly Klamer, M.S., R.D., “but in general terms, it means following a diet that has less than 45–65 percent of [total daily] calories from carbohydrates.”
(For reference, the recommended carbohydrate range for adults, according to the 2015–2020 Dietary Guidelines for Americans, is 45–65 percent of total daily calories.)
In general, however, most low-carb diets focus on limiting refined grains and starches (like white bread, pasta, and potatoes) in favor of lean protein, whole grains, non-starchy veggies, and low-glycemic fruits.
But with so much varying information out there, it can be easy to misinterpret a low-carb diet or to implement its principles in an extreme or unsustainable way.
The intention behind the diet — to reduce the amount of unhealthy carbs you consume on a regular basis — isn’t inherently a bad idea, but you need to be smart about how you execute it. Here are seven common mistakes to avoid.
7 Common Low-Carb Diet Mistakes
1. Ignoring the nutritional value of carbs
These foods provide our bodies with the natural, sustained energy we need to function and stay active. “A carbohydrate-dense fruit such as a banana can give you the fuel you need to increase the intensity of your workout; [you might] burn more calories [as a result],” says Klamer.
High-quality carbs are also chockful of vital nutrients like B vitamins, potassium, fiber, and vitamin C. Klamer says reducing your carbohydrate intake to super low levels puts you at risk for deficiencies in these areas.
2. Eating too much unhealthy fat
Eating low-carb isn’t an excuse to go nuts on beef, pork, eggs, butter, cheese, and other foods with high trans or saturated fat content.
Eating a diet high in trans fat isn’t heart-healthy, says Sharon George, M.S., R.D., C.D.N. Consuming high levels of trans fat may cause your liver to produce more LDL cholesterol, the “bad” cholesterol.
According to the American Heart Association, too much “bad” cholesterol (LDL) and not enough “good” cholesterol (HDL) may put you at risk for certain types of disease.
In fact, one study carried out by the Harvard School of Public Health found that a low-carb diet high in animal protein (dairy and meat) was associated with higher all-cause mortality, while a low-carb diet high in plant protein (veggies, tofu, lentils, etc.) and lower in trans fat was associated with lower all-cause mortality rates.
Researchers found that substituting saturated fats with polyunsaturated fats and limiting consumption of refined carbohydrates may be beneficial for overall health.
The overall takeaway: Cut back on trans and saturated fat consumption, while also reducing refined carbs (think: white bread, pasta, rice, sugary pastries, cookies, etc.).
Instead, eat healthy fats, such as mono- and polyunsaturated fats, as well as omega-3 fatty acids. Great sources of these types of fats include salmon, flaxseeds, walnuts, avocados, seeds, nuts, and extra-virgin olive oil.
3. Misunderstanding portion sizes
If you don’t have a basic idea of portion sizes — say, what a single portion of brown rice or steel-cut oats actually looks like — you’re likely to either over- or underestimate how much food you need.
Understanding portion sizes can help prevent overeating while also ensuring you consume enough nutrients to fuel your body properly.
Denis Faye, M.S. and Beachbody’s executive director of nutrition, says the Portion Fix plan advocates for a healthy balance of macronutrients: 30 percent of your total daily calories from protein, 30 percent from healthy fats, and 40 percent from carbs — the majority of which should be unprocessed and unrefined.
“By going with 40 percent carbs, we’re able to make the majority of carbs [in the plan] produce-based without crushing people [who are] new to healthy eating under a kale, broccoli, and mixed-berry avalanche,” says Faye.
There are three containers for carbs in the system: Purple is for fruits, green is for veggies, and yellow is for other carbs like whole grains. You fill each one up with its corresponding foods anywhere from two to six times a day, depending on your predetermined calorie target range; no measuring or overthinking necessary.
Faye also notes that the 40 percent carbs guideline isn’t a hard-and-fast rule: “Starting your diet at 40 percent carbs allows you to experiment and increase your carbs to a level that best works for you, which is much easier than trying to slowly reduce carbs to find your sweet spot,” he explains.
4. Eating too much protein
“Getting enough protein is hugely important for both health reasons and because it aids muscle recovery,” says Faye. (Protein breaks down into amino acids, which are the building blocks of muscle.)
Eating less carbs certainly means you’ll need to eat more protein (especially if you want to crush your workouts), but it’s important not to go overboard.
“When [your] carbohydrate intake is significantly decreased, the body starts breaking down stored carbohydrate sources [glycogen, for energy],” says Klamer. “When these stores get depleted, the body will start altering fat and protein to make carbohydrates.”
Gluconeogenesis (which means “creating new sugar”) is the metabolic process by which the liver converts non-carbohydrate sources (like fats, amino acids, and lactate) into glucose to regulate blood sugar levels.
Gluconeogenesis usually occurs when your body doesn’t have sufficient carbohydrates to properly fuel your brain and muscles.
Amino acids (the building blocks of protein) can’t be stored for long-term energy, which means the body has to convert this excess protein into either glucose or fat storage, possibly negating the effect of eating low-carb and making it more difficult to lose weight.
To avoid getting too much of a good thing, aim for protein to make up a solid 30 percent of your diet, not half. For ideas, check out these healthy, high-protein snacks for when you’re on the go.
5. Not considering activity level when determining carb intake
“Carbs are fuel. They’re massively important and the body is super efficient at processing them, which is a blessing and a curse,” says Faye. “If you get the right amount [of carbs], they’re the ideal fuel for exercise, health — even for fueling your brain.”
But what’s the ideal amount? That depends, in part, on your level of activity and how much weight you want to lose. If you exercise a few times a week and make a point to move often throughout the day, you probably don’t need more than 40 percent of your daily calories from carbs. This amount ensures you get enough carbs to energize and fuel your body, but not so many that you can’t burn them off through regular exercise and your daily 10,000 steps.
6. Eating too many carbs
Just as it’s possible to eat too few carbs when starting a low-carb diet, it’s also possible to eat too many.
What constitutes an excess of carbs varies for each individual depending on metabolism and activity level, but in general, consuming more than 45 percent of your total daily calories from carbs isn’t technically a low-carb diet plan, according to the 2015–2020 Dietary Guidelines for Americans.
If carbs make up half or the majority of your food consumption, you may be missing out on other essential macronutrients like lean protein and healthy fats. Protein is necessary for building muscle, and healthy fats provide our bodies with energy, aid in nutrient absorption, and facilitate cell growth and function.
7. Eating too many processed low-carb foods
Just because a food is low-carb doesn’t mean it’s automatically healthy. Highly processed foods like bacon, certain deli meats, and low-carb snack bars don’t have many carbohydrates, but they’re often loaded with excess sodium, trans fats, and other additives.
Eating low-carb foods with refined and processed ingredients may not provide you with the nutrients you need to feel satisfied and energized. Before you load your shopping cart or plate with any item that has a low-carb label, consider the quality of the food in front of you.
If a food contains refined grains, artificial additives, added sugar, or ingredients you can’t pronounce or wouldn’t cook with at home, it’s probably highly processed.
Whenever possible, choose whole or minimally processed carbs. “Naturally occurring carbohydrates like the ones found in whole foods such as whole grains, dairy like yogurt and milk, and fruits and vegetables, provide important nutrients,” says Gorin.
How to Reduce Your Carb Intake in a Healthy Way
Adopting new eating habits takes time and patience, which is why it’s important to go slowly and be realistic about your expectations for weight loss.
“Many people get discouraged when starting a low-carb diet because it can take weeks to see results [from actual fat loss],” says George. Though you might see a lower number on the scale in the first week of eating low-carb, this change is probably a result of losing water weight.
The process of shedding fat and gaining muscle, however, might be more gradual. If that’s the case, remember that slow and steady wins the race.
Cut back on less-healthy carbs first
“If you’re looking to reduce carbohydrate intake,” says Gorin, “I recommend reducing the types of carbs that aren’t beneficial — [like] processed foods that contain added sugars and refined [grains].”
Items such as soda, candy, desserts, chips, and other processed foods don’t supply your body with enough vital nutrients. You don’t need to completely nix these foods from your diet, though (unless you want to!).
Instead, aim to enjoy them sparingly and with smart modifications. With Beachbody’s Portion Fix Eating Plan, for example, you can indulge in the occasional treat made at home using whole foods and natural ingredients, such as unsweetened applesauce, pure maple syrup, or extra-virgin coconut oil, to make treats like peanut butter chocolate chip cookies, strawberry lemonade bars, or red velvet cupcakes.
Eat carbs with more nutritional value
“If you are choosing to eat less carbs, it is important to make the carbs you do eat as nutritious as possible,” says Klamer. Try to eat low-glycemic, high-fiber carbs whenever you can.
For more fiber and nutrients, Klamer recommends whole-grain bread, whole-wheat pasta, and brown or wild rice. Other fiber-rich foods include black beans, lentils, broccoli, barley, artichokes, and raspberries.
(Pro tip: Need ideas on how to lose weight and get fit? Download our free “100 Ways to Lose Weight” guide here!)
High-Quality, Nutrient-Rich Carbs
Not sure which carbs to enjoy? Here are some examples of totally delicious and Portion Fix-approved carbs to add to your diet:
- Sweet potato
- Beans (kidney, black, garbanzo, white, lima, fava, etc.)
- Brown rice
- Wild rice
- Potato, mashed or ½ medium
- Corn on the cob, 1 ear
- Oatmeal, rolled
- Pasta, whole-grain
- Couscous, whole wheat
- Bread, whole-grain, 1 slice
- Pita bread, whole wheat, 1 small slice (4-inch)
- Bagel, whole-grain, ½ small bagel (3-inch)
- Tortilla, whole wheat, 1 small (6-inch)
*Green and purple containers:
- Peppers (sweet)
- Winter squash
The 20-Second Takeaway
Many people who start low-carb diets take them to extreme measures, and can end up drastically reducing their carb intake, consuming large amounts of unhealthy fats, or not incorporating enough nutrient-rich carb sources into their meals.
That doesn’t mean low-carb diets are bad, though — they can be an effective weight-loss strategy, but you need to be thoughtful about the approach you take.
In general, focus on limiting processed and refined carbs, and eating more high-quality carbs from whole grains, fruits, and veggies. You’ll gradually lose weight and get all the nutrients you body needs to thrive.