The Atkins Diet

Steak with Bearnaise sauce, eggs and bacon, cheddar cheese omelets -- don't hold the yolks, Roquefort dressing, and silky smooth avocado cream soup made with real cream? These rich foods are allowed as part of the controversial diet described in Dr. Atkins' New Diet Revolution, a phenomenal best seller, and several follow-up books, including the 2010 New Atkins for a New You.

The Atkins diet promises that not only will you lose weight -- and not be hungry -- with a low-carbohydrate diet, but you'll also be on the road to better heart health and memory function, as well as other wellness benefits.

The diet is based on the theory that overweight people eat too many carbohydrates. Our bodies burn both fat and carbohydrates for energy, but carbs are used first. By drastically reducing carbs and eating more protein and fat, our bodies naturally lose weight by burning stored body fat more efficiently.

Although it's undoubtedly the weight-loss claims -- and noted success stories -- that are selling the books, the Center for Complementary Medicine in New York (which Atkins founded) claims that most people follow the Atkins diet for weight maintenance, good health, and disease prevention.

Drastically restricting carbohydrates to a mere fraction of that found in the typical American diet causes the body to go into a state of ketosis, which means it burns its own fat for fuel. A person in ketosis is getting energy from ketones, little carbon fragments that are the fuel created by the breakdown of fat stores. When the body is in ketosis, you tend to feel less hungry, and thus you're likely to eat less than you might otherwise. However, ketosis can also cause a variety of unpleasant effects (such as unusual breath odor and constipation) in a small number of people.

As a result, your body changes from a carbohydrate-burning engine into a fat-burning engine. So instead of relying on the carbohydrate-rich items you might typically consume for energy, and leaving your fat stores just where they were before (alas, the hips, belly, and thunder thighs are popular fat-gathering spots), your fat stores become a primary energy source. The purported result: weight loss.

In slightly more detail, consider what happens when you eat a high-carbohydrate meal. Sugar from the carbohydrate quickly enters the bloodstream. To keep the blood sugar from rising too high, the body secretes insulin. Insulin allows the extra sugar to be stored in the liver and muscle as glycogen, but these stores are rapidly filled to capacity. The insulin then converts any extra sugar to fat -- the stuff we're trying so hard to get rid of.

According to the Atkins theory, if the body keeps on making "too much" insulin -- as it tries to deal with the "excess" sugar -- it may become less responsive to insulin and eventually may develop the metabolic disorder diabetes. The Atkins theory states that this should properly be called "unstable blood sugar" since the blood sugar level rises and then drops quickly.

This "first step in an unhealthy metabolic path" leads to "the early stages of diabetes." However, a body in ketosis burns up excess fat, and in time -- according to the Atkins theory -- returns to normal metabolic function. Though all the fat in this diet may temporarily spike someone's cholesterol level, this is usually short lived and soon rights itself with a lower cholesterol and triglyceride level as weight loss occurs -- at least, that's the theory.

For most people, the carb consumption must be no more than 40 grams a day for this biochemical mechanism to occur. Although exercise isn't stressed, the Atkins theory holds that some people will need to add physical activity for ketosis to kick in. People are urged to supplement with vitamins, since they won't be getting them from sources such as vegetables and fruits.

The plan allows you to eat foods that many dieters have only dreamed about. The diet is said to work even if other diets have left you feeling depressed and deprived. The Atkins diet at a glance:

• Sets few limits on the amount of food you eat but instead severely restricts the kinds of food allowed on your plate: no refined sugar, milk, white rice, or white flour
• Allows you to eat foods traditionally regarded as "rich": meat, eggs, cheese, and more
• Claims to reduce your appetite in the process

On the Atkins diet, you're eating almost pure protein and fat. You can consume red meat, fish (including shellfish), fowl, and regular cheese (not "diet" cheese, cheese spreads, or whey cheeses). You can cook with butter, have mayo with your tuna, and put olive oil on your salads.

On the other hand, carbs are restricted (about 20 grams of net carbs per day, meaning total carbs minus fiber) in the first two weeks, which translates to three cups of loosely packed salad or two cups of salad with two-thirds cup of certain cooked vegetables each day.

There are no exceptions to these rules during the first two weeks because low-carb consumption (no fruits and only a few leafy green vegetables) is supposed to jump-start the weight-loss biochemical activity of the diet. You're not counting calories (in fact, you may be eating more calories than you were before).

Later, the carb allowance is increased in the form of fiber-rich foods, but you do not return to eating refined sugar (by the teaspoonful or in desserts), milk, white rice, white bread, white potatoes or pasta made with the dreaded white flour. Those remain on a lifelong list of forbidden pleasures.

The diet does allow for adding fruits, vegetables, and whole-grain foods after the two-week induction period.

Then, over time, the transition from weight loss to weight maintenance is made by gradually increasing carbs so long as gradual weight loss is maintained.

Exercise in all phases as part of a healthy lifestyle is now emphasized more than when the diet was first introduced.

Both in the U.S. and abroad, the Atkins diet remains highly controversial.

An Atkins spokesperson points out that a number of studies since 2002, including those funded by the American Heart Association, the National Institutes of Health, and the Philadelphia Veterans Administration, demonstrate some benefits of a low-carbohydrate diet -- especially when weight-loss results achieved with a diet like the Atkins plan are compared to weight-loss results on other diet plans.

But many health experts remain wary. "The Atkins diet is a viable option that requires more testing," Gary D. Foster, PhD, clinical director of the weight and eating disorders program at the University of Pennsylvania, tells WebMD. "The Atkins diet works at producing weight loss. If you are looking for weight loss, yes, it works. If you are looking for improvement in triglycerides and HDL cholesterol, yes, it works."

But Foster, like other experts, remains concerned about the long-term safety of the diet.

Robert H. Eckel, MD, director of the general clinical research center at the University of Colorado Health Sciences Center in Denver, agrees. He tells WebMD, "Our worries over the Atkins diet go way past the question of whether it is effective for losing weight or even for keeping weight off. We worry that the diet promotes heart disease. ... We have concerns over whether this is a healthy diet for preventing heart disease, stroke, and cancer. There is also potential loss of bone, and the potential for people with liver and kidney problems to have trouble with the high amounts of protein in these diets."

The American Dietetic Association also has concerns about the Atkins diet. Gail Frank, PhD, former spokeswoman for the organization and professor of nutrition at California State University in Long Beach, says, "The body needs a minimum of carbohydrates for efficient and healthy functioning -- about 150 grams daily." Below that, normal metabolic activity is disrupted.

"The brain needs glucose to function efficiently, and it takes a long time to break down fat and protein to get to the brain," says Frank. Carbohydrates, especially in the form of vegetables, grains, and fruits, are more efficiently converted to glucose. And this more efficient use of glucose has developed over a long period of time, according to Frank. "Fruits and berries are much more indicative of early man's eating pattern than eating only protein, and we haven't changed all that much physiologically."

Volumetrics author Barbara Rolls, PhD, who holds the Guthrie Chair in Nutrition at Penn State University, offers this: "No one has shown, in any studies, that anything magical is going on with Atkins other than calorie restriction. The diet is very prescriptive, very restrictive, and limits half of the foods we normally eat," she says. "In the end it's not fat, it's not protein, it's not carbs, it's calories. You can lose weight on anything that helps you to eat less, but that doesn't mean it's good for you."

The Atkins diet has changed and improved over the years to promote a variety of foods including lean protein, vegetables, fruits, nuts, legumes, and in some cases, whole grains and healthy fats.

WebMD Medical Reference