The 21-day Wonder Diet Plan

The 21-Day Wonder Diet Plan promises rapid weight loss of up to 10 kg -- 22 lb. -- in three weeks. The low-fat, low-calorie diet may help you lose some weight, but it's mathematically all but impossible to lose a pound a day of fat. The plan provides some healthy recipes that may help you reach more realistic goals, but don't buy the diet book before separating the authors' hype from scientific fact.

Diet Basics

The Centers for Disease Control and Prevention describes American society as "obesogenic," an environment that promotes increased intake of foods. Such an environment breeds obesity -- and fascination with fad diets such as the 21-Day Wonder Diet Plan produced by the "Australian Women's Weekly" magazine. The book provides recipes that keep your fat intake below 20 g daily and your calorie count to about 1,000. The authors do not explain -- perhaps because they cannot -- how a 1,000-calorie yields a weight loss of 22 lb. in 21 days.

Doing the Math

A woman needs about 2,000 calories a day to maintain her current weight. In order to lose 22 lb., she needs to create a calorie deficit of 77,000 calories. Without dieting, a woman would consume about 42,000 calories in 21 days. Even if you consumed no food in 21 days, you'd need to burn off another 35,000 calories in exercise in order to lose 22 lb. of fat. You may lose water weight from the diet's restriction of carbohydrates, but such weight loss won't be permanent. On a 1,000-calorie diet, you could expect to lose 6 lb. of fat in three days, based on the formula that a pound of fat contains 3,500 calories.

Precautions

You put your health at risk by consuming only half of your daily caloric requirements. This holds particularly true for anyone suffering from disease. Pregnant women also should avoid extreme diets as they need enough calories to support a developing fetus. But even if you don't fall in the high-risk category for following a very low-calorie diet, consult with a health professional before embarking on the 21 Day Wonder Diet or any other weight loss plan.

Alternative Approach

You can lose weight without following an extreme regimen such as the one dictated by the 21-Day Wonder Diet Plan. You could follow a moderate diet -- about 1,500 calories -- recommended by the United States Department of Agriculture or simply cut junk food out of your diet. The "International Journal of Obesity" states that obesity is usually the result of an excessively positive energy balance, due to consuming more than the body needs. You don't need to buy a book or consult a calorie counter to know that you body doesn't need a slice of cake for dessert.