How Much Weight Can You Lose in 14 Days of No Carbs?

On a low-carb diet, weight loss in two weeks depends on your overall calorie intake and the nutritional value of the foods you choose to eat. Many carb-heavy foods are high in calories and wreak havoc on your blood sugar, and cutting out these carbs is good for your health — diet or no diet. But cutting out all carbs could end up making you feel sick, which may sabotage your weight-loss efforts.

The internet is rife with misinformation and misconceptions about carbohydrates. "All carbs make you gain weight," "Your body can't burn fat when you eat carbs," and so on. Many people buy into this dogma without realizing that there's little scientific evidence to support it.

Here's the truth: Some carbs aren't all that healthy and in some circles are labeled bad , and others are healthy — in fact critical to health. You have absolutely nothing to gain and much to lose by cutting all carbs out of your diet for two weeks. Here's why:

• Carbs are your body's main source of energy. You need some carbs to fuel your daily activities of living and exercise — a critical component of weight loss. The sugar glucose — the product of carbohydrate metabolism — also provides energy for the brain; in fact, the brain uses 20 percent of glucose-derived energy, according to a review published in Trends in Neurosciences in October 2013.
• Vegetables, fruits and whole grains provide a type of carbohydrate called dietary fiber, which is crucial for normal digestion and the prevention of digestive diseases. Dietary fiber also helps control blood sugar and lower cholesterol. Last, dietary fiber slows digestion and makes you feel full, which can help you control your appetite and calorie intake.

Cutting out all carbs for two weeks isn't likely to cause long-term damage; however, it can have some uncomfortable effects. Many people complain of hunger and food cravings. If you ate a lot of refined and processed carbs and sugar, which have addictive properties according to a February 2018 study in PLoS One, you could find the withdrawal to be difficult. Many people aren't able to handle it and end up on a carb-binge. That's not going to help with weight loss.

Read more: 10 Convenient Low-Carb Snacks

In addition, a sudden decrease in carbs may cause you to experience:

• Headache
• Bad breath
• Weakness
• Muscle cramps
• Fatigue
• Skin rash
• Constipation or diarrhea

If you're following a very low-carb high-fat diet like the ketogenic diet, you may experience something called the "keto flu," symptoms of which include:

• Nausea
• Vomiting
• Headache
• Fatigue
• Dizziness
• Insomnia
• Exercise intolerance
• Constipation

Doesn't sound like much fun. Some of these effects can be disruptive to your normal everyday functioning. Even if cutting out all carbs for two weeks does help you lose a little weight, is it really worth it?

Maybe you're still gung-ho to ditch all the carbs, or maybe you've reconsidered. Either way, there are a lot of carbs you can feel free to abstain from — not just for two weeks, but for life. These are simple carbs, from refined grains and sugar, found in:

• White bread and white pasta
• Anything made with white flour
• Candy, cake, cookies and pastries
• Pretzels, French fries, potato chips and other snack foods
• Pancakes and waffles
• Sugary cereals
• Fruit juice
• Soda and other sweetened beverages
• Table sugar and anything containing other derivatives of sugar, including brown rice syrup, dextrose, maltose and corn syrup — even honey and agave syrup

Why are these foods so bad for your health and for weight loss? Here's why:

They are high in calories and low in nutrients. Some, including sugary candy, drinks and desserts, provide no nutrition at all — just empty calories.

They're low in fiber. Remember that dietary fiber that offers so many benefits to your health? It's almost non-existent in the list of "foods" above.

They spike your blood sugar. Maybe you've experienced a "sugar high" before — that rush of energy you get after eating a candy bar or drinking a soda. Simple carbs are simple in chemical structure; your body breaks them down quickly, and glucose floods your bloodstream. This leads to a quick energy surge and then an energy crash.

They make you overeat. In addition to their high calorie-to-nutrient ratio, the blood sugar spike you experience after consuming simple carbs can leave you feeling hungry soon after eating. You might find yourself reaching for another sugary snack just to pick you up again. That's a surefire way to exceed your calorie needs and gain weight.

If you've been eating some — or all — of the carbs on the list above, cutting these out of your diet can significantly reduce your calorie intake and help you lose up to several pounds in two weeks. According to the National Institutes of Health, you can lose 1 to 2 pounds per week by creating a calorie deficit of 500 to 1,000 calories a day. If you consider how many calories are in soda, donuts, chips and candy, you can easily see how avoiding those can get you to this deficit.

However, it makes a difference what other foods you plan to eat over the next two weeks. If you're doing the keto diet, you may be getting up to 90 percent of your calories from fat, according to Harvard Health Publishing. Nutritionally, there's nothing wrong with that in the short-term; however, it can hamper your weight loss efforts if you don't do it right.

Fat has 9 calories per gram, versus carbohydrate and protein, which have 4 calories per gram, according to the USDA. Because fat is so calorically dense, it's easier to exceed your daily calorie needs when you eat a lot of it. A mistake some keto dieters make is thinking they can binge on fatty foods as long as they're not eating carbs and they're in ketosis — the metabolic state in which your body is using fat for fuel and creating ketones to provide energy. However, if you're eating too many calories, you're going to gain weight, not lose it.

Read more: Irresistible Avocado Toast Recipes For a Keto Diet

Maintaining a calorie deficit through a balanced, calorie-controlled diet and regular exercise is key to weight loss. Instead of cutting out all carbs, consider only cutting out those that are unhealthy for you. Keep the healthy carbs in your diet, such as fresh fruits, vegetables and whole grains.

If you want to cut out the latter category for two weeks, go ahead — it won't hurt. But a long-term weight loss diet is one that is nutritionally balanced and contains all the major food groups. Diets that encourage ditching one or more food groups are considered fad diets, which the Academy of Nutrition and Dietetics warns staying away from. These diets aren't sustainable long-term; when you go back to your normal eating habits, you're likely to gain back any weight you may have lost.