But some aspects of Eat Yourself Thin are useful, says Holden. In particular, the book's focus on calorie counting can be useful.

How Many Calories Do You Need

"The best thing about the book is that it teaches people how to calculate an approximate basal metabolic rate," says Holden. "That's the number of calories your body needs every day to maintain a constant weight. The number is different for everyone."

The book, says Holden, tells readers to establish their ideal body weight and then multiply that number by 10 to arrive at the daily calorie intake. For example, if your ideal body weight was 130 pounds, you would multiply that 130 by 10 to get 1,300 calories per day.

"That is a very rough estimate of what you need to eat each day at your ideal weight," says Holden. "So that gives you a place to start. If you weigh 160 pounds, and your ideal weight is 130 pounds, then you start a calorie diary to see how much you're eating each day. Then you can get a better idea of how much you can eat every day to start working off weight to get closer to your ideal weight."

That much, she says, is useful. But the book goes on to tout the wonders of low-carb eating as the best way to maximize loss of body fat.

"That's the part you want to avoid," says Holden. "Low-carb diets provide quick weight loss but do not help you maintain weight loss."

The American Dietetic Association (ADA) says that both low-carb and high-protein diets are bad.

"These diets are not safe, they are not healthy, and they are not a good way to try to get healthy," says Leslie Bonci, RD, nutritionist with the University of Pittsburgh Medical Center Sports Complex and a spokesperson for the ADA. "They provide short-term, rapid weight loss by causing the body to shed water weight and muscle. But that is no way to keep weight off for very long, and it's dangerous to your body chemistry."

Dangerous Process

According to the ADA, low-carb diets and others like it trigger short-term weight loss through a process called ketosis. This process kicks in when your body is in short supply of carbohydrates, a prime source of energy for the entire body, but especially for the brain, which operates exclusively on carbohydrates.

During ketosis, your carbohydrate-depleted body grabs other sources, including ketones from stored fat or protein, to satisfy daily energy needs. This leads to ketoacidosis, a state similar to that seen with type 1 diabetes. This type of diet can have a negative long-term impact on health.

"Next time you talk to someone on one of these diets, pay attention to their mental state, how alert they seem," says Holden. "The lack of carbohydrates tends to make them seem a bit fuzzy mentally because the brain is not getting enough fuel. Is that any way to diet?"

New Research Supports It

But a study in the July 2002 issue of the American Journal of Medicine showed that the most famous of low-carb diets, the Atkins diet, does work.

Study participants lost an average of 20 pounds while on the Atkins diet for six months, but they were not followed longer to see if they kept the weight off. Most people also had improved cholesterol levels at the end of the study, even though the eating plan permits unlimited quantities of cholesterol-rich foods such as eggs and meat.

The study was funded by a grant from the Robert Atkins Center for Complementary Medicine. Duke researcher Eric Westman, MD, says he became interested in studying the Atkins diet after several of his patients lost large amounts of weight on it.

But though researchers were impressed by the weight loss, they say more study is needed to pronounce the carbohydrate-restricting diet safe.

Safe Dieting

Here's how the American Heart Association says to take weight off, and keep it off.

Be active: try walking 30 minutes a day most days of the week.

To lose weight, most women should eat 1,200-1,500 calories per day.

To lose weight, most men should eat 1,500-1,800 calories a day.

A loss of one to two pounds per week is considered a healthy weight loss.

People who lose weight gradually are more likely to keep the weight off.

Eat no more than 30% of your total calories from fat.

Include at least five servings of fruit and vegetables in your diet each day.

Examine your eating habits -- keep a written journal of what and when you eat.

Weigh yourself only once a week.

Eat breakfast to curb binge eating.

"There are still a lot of things we don't know about food and nutrition," says Holden. "Nutrition is a relatively young science, but we do know that you can trick the body's mechanisms in the short run. In the long run, however, those short cuts catch up with you in the form of weight gain."

Source: WebMD