You can lose weight by eliminating carbs for 14 days, but there's no guarantee you'll drop any pounds if you don't watch calories. Carbs account for half or more of total daily calories for most people. Because you'll need to replace some of those calories -- if not all of them -- with other foods, be sure you don't end up consuming more calories than you got with carbs. Don't follow a zero-carb diet longer than 14 days unless you consult a doctor or registered dietitian.
Drop Carb-Related Water Weight
When blood levels of sugar get too high, some of the excess sugar goes to the liver, where it's turned into glycogen or fat and sent into storage. Glycogen is stored in the liver and muscles, where it's rapidly turned back into glucose when needed for energy. The body has limited storage space for glycogen, so when it's full, extra sugar is stored as fat.
Most people have about 2,000 calories of stored glycogen. Long-term endurance training increases the amount of glycogen in muscles, so if you consistently train, you may have slightly higher glycogen stores. When you eliminate carbs, glycogen stores aren't refilled after they're used. You can deplete all glycogen after about 90 minutes of low-intensity exercise, reports Iowa State University.
If you're an active person or involved in sports, your performance will suffer if you don't refill glycogen, but losing glycogen is a boost if you're trying to drop a few pounds. Each gram of glycogen holds 2.7 grams of water, according to the American Council on Exercise. As you use glycogen for energy, you also lose the water associated with each gram of glycogen. As a result, you'll lose 3 to 5 pounds of water weight fairly quickly. How much you lose for the rest of the 14 days will vary from person to person and will depend on your overall diet.
Calorie Management for Weight Loss
The amount of weight lost beyond water weight depends on the total number of calories consumed. If you replace all the calories lost from eliminating carbs with other no-carb foods, you won't lose any additional weight. But if you restrict calories, it's easy to estimate the number of pounds you'll drop in addition to carb-related water weight.
Begin by determining exactly how many calories you currently consume. If you don't know, take a few days to keep track of everything you eat and drink, then tally the calories and use that number to see how many calories you can cut while maintaining your health. You should consume at least 1,200 to 1,400 calories daily, which is what you need to sustain your body's essential life support, according to Columbia University. The difference between your current calorie consumption and 1,200 is the maximum number of calories you should cut.
If your daily caloric intake is 2,200 calories, you could cut 1,000 calories daily and still get 1,200 calories. Over 14 days, that equals a loss of about 4 pounds because you have to burn 3,500 calories to lose 1 pound. Now you've lost 7 to 9 pounds by cutting out carbs and reducing calories.
Support Weight Loss With Exercise
The number of calories burned during activity depends on your weight, the type of exercise and the length of time spent exercising. For example, a person who weighs 125 pounds burns 90 calories from playing volleyball for 30 minutes and 300 calories by jumping rope for the same amount of time, according to Harvard Medical School. Thirty minutes of vigorous bicycling and running burn 495 calories in a 125-pound person, while a person weighing 185 pounds uses 733 calories.
However, for the 14 days on a no-carb diet, you may not have enough energy for strenuous exercise. Doing some light activity -- such as walking for 30 minutes daily and doing resistance training two days per week -- will help keep you fit while you're limiting carbs.
Regular exercise will help you keep the weight off when your diet returns to normal. If you exercise for 30 minutes every day and engage in activities that burn 250 calories, you'll lose 1 more pound. Of course, if you double the time spent exercising, you'll lose 2 pounds in addition to the 7 to 9 pounds already lost. And there's a bigger payoff: the health benefits from exercise. It helps lower blood sugar, strengthens muscles, preserves bone mass, reduces stress and lowers your risk for heart disease.
No-Carb Diet Considerations and Concerns
Eliminating carbs may help you lose weight through two other actions, but the impact on total pounds lost is hard to determine. Blood sugar doesn't spike if you don't eat carbs. As a result, insulin isn't secreted, which is good for weight loss because insulin signals the body to store fat rather than burn it. Researchers found that after people lost weight, if they continued to follow a low-carb diet their metabolic rate stayed higher compared to people who resumed a low-fat diet, according to the Journal of the American Medical Association in 2012.
Fats are metabolized and used for energy when the body doesn't have carbohydrates. During the breakdown of fat, ketone bodies are formed. These are essential because the brain can use them for energy. As ketones build up in your body, you may experience side effects such as nausea, headache, fatigue and bad breath, but if you're healthy and limit the diet to 14 days, they shouldn't be cause for alarm. High levels of ketones should be avoided by pregnant or breast-feeding women, however, and they're dangerous for anyone with kidney disease or diabetes.
- Iowa State University Extension and Outreach: Carbohydrate
- American Council on Exercise: Why Do I Seem to Gain Weight When I Start to Train for an Endurance Race Like a Half Marathon?
- Columbia University: Go Ask Alice: Ideal Caloric Intake?
- Centers for Disease Control and Prevention: Losing Weight
- Harvard Medical School: Calories Burned in 30 Minutes for People of Three Different Weights
- University of California, San Francisco: Benefits of Exercise
- Journal of the American Medical Association: Effects of Dietary Composition During Weight Loss Maintenance: A Controlled Feeding Study
- Columbia University: Go Ask Alice: Are Low Carb Diets Safe?
- University of California, San Francisco: Ketones