Losing up to 22 pounds in 13 days certainly sounds like a winning diet if you want to lose weight fast. However, the 13 Day Metabolism diet is a fad diet with strict rules and severe calorie restriction that you may have a hard time following for the allotted days. Because the diet is nutritionally inadequate, consult your doctor to discuss if it's a safe option for you.
About the 13 Day Metabolism Diet
The 13 Day Metabolism diet is also known as the "Royal Danish Hospital diet." Although the word "hospital" appears in this name, no hospital is behind the making of this diet, reports Diets in Review. The 13-day diet claims that it jump-starts your weight loss and bumps up your metabolism so that when you go back to your usual eating habits after following the diet for two weeks, you never have to diet again. Additionally, you are only supposed to go on the 13 Day Metabolism diet once every two years, and if you're unable to complete the full 13 days, you cannot resume the diet for six months.
What You Eat
During the 13-day diet, you eat two to three meals a day consisting of a mix of coffee, vegetables such as carrots, spinach and celery, fruit such as orange juice and apples, yogurt and protein foods such as boiled eggs, chicken, fish and beef. Toast is also on the menu a few days on the plan, but no other grains. Some mornings you do not eat any food but drink only coffee with sugar. In addition to skipping meals, some days you do not eat any fruit or any vegetables throughout the entire day. A typical day might include coffee with sugar and toast for breakfast, yogurt and carrots for lunch and boiled eggs with spinach for dinner. Overall, the calories vary greatly from day to day, but caloric intake is too low for most people throughout the diet.
The 13-day diet may be a type of calorie-cycling diet, sometimes referred to as a "calorie-shifting" diet. These types of diets vary your daily calorie intake -- you eat more on some days, less on others -- and theories abound as to the possible benefits. One idea is that the diet purportedly activates genes or hormones that promote fat burning, according to Berkeley Wellness.
You'll lose weight following the 13 Day Metabolism diet but not because of a magical combination of foods; instead, the diet helps you lose weight by severely restricting your calorie intake. On average, you'd consume 800 calories or fewer a day on this diet. The National Institute of Diabetes and Digestive and Kidney Diseases says you should not eat fewer than 800 calories a day unless directed to do so by your doctor. On many days of the diet, breakfast is simply coffee with one lump of sugar, which is essentially skipping breakfast. Other days, you're allowed a single slice of dry toast with your coffee. Restricting your caloric intake to such extremes makes it difficult to meet all your essential nutrient needs.
Additionally, cutting your calories too low may have the opposite effect on your metabolism and cause it to slow down. Also, when you lose weight quickly, you're most likely losing muscle, which is a major contributor to your metabolic rate and may cause it to slow down even further.
How to Up Your Metabolism
If you want to lose weight and rev up your metabolism, you need to eat enough calories, but not too many, and add strength-training exercises to your daily routine. Restricting calories is part of any weight-loss diet, but the McKinley Health Center says women should not eat fewer than 1,200 calories a day, and men should not eat fewer than 1,800 calories a day. Your doctor or dietitian can help determine your weight-loss calorie needs.
To keep your metabolism burning while you lose weight, you want to increase your muscle mass. That doesn't mean you need to bulk up, but you need to do strength-training exercises, such as lifting weights or yoga, at least two days a week.
Also include aerobic activity, a minimum of 150 minutes a week or 30 minutes five days a week to burn a few extra calories throughout the day to help you lose the weight. Because of the severe calorie restriction of the 13 Day Metabolism diet, exercise is not part of the plan.