There is no bad guy when it comes to food. A calorie is a calorie is a calorie, goes a famous saying among nutritionists. “Promoters of dietary schemes such as The Atkins diet and the Zone would have us believe that a special substance or combination of foods will automatically result in weight reduction,” says George Rapitis, BS, a nutritionist and a member of the American Dietetic Association. “That's simply not true. To lose weight, you must eat less, or exercise more, or do both.”
Other fad diets and scams blame hormones or chemicals in your body, and offer magical solutions to deal with supposed unbalances. One such example is the Blood-Type Diet, based on a book written by Peter D’Adamo. “According to naturopath Peter J. D'Adamo, your blood type is a genetic fingerprint that is more powerful than race, culture or geography,” says Rapitis. “D'Adamo, unfortunately, it offers little in the way of scientific evidence, relying instead on a collection of anecdotal reports and case histories. His speculation that the one gene responsible the ABO blood type could exert such a dominant influence over everything else is unable to stand on its own merits.”
They promise results
There is no one-size-fits-all when it comes to dieting. People have different metabolisms, different lifestyles, and different eating habits. What works for a 250-pound man who needs to lose 50 pounds would probably not work for a 150-pound woman who only wants to lose 10. Diets that promise everybody will lose weight are most likely too extreme to be healthy.
They promise a quick fix
Fat is stubborn. Not matter how much you diet and exercise, it is basically impossible to lose more than two pounds of fat in any given week. Some extreme diets may appear to work faster, but this is simply an illusion. “As [a diet] begins, large amounts of water will be shed, leading the dieter to think that significant weight reduction is taking place,” says Rapitis. “However, most of the loss is water rather than fat; the lost water is regained quickly when eating is resumed.”
The major problem with extreme diets is that the pounds lost rarely come from the right source. “Fad diets […] can cause a 3-6% loss of muscle along with any fat lost,” says Rapitis. “If the weight is regained, more fat and less muscle is replaced, resulting in less overall muscle protein.”
Even when they work, extreme diets do not offer a long-term solution to weight problems.