Atkins Diet: What You Need to Know

A plate with salmon and some vegetables.
The Atkins diet allows you to eat fairly large amounts of red meat, eggs, cheese, butter, and even bacon - all of which would be considered contraband on other plans. lacaosa / Getty Images

Let's face it, you or someone you know has been on a diet at one time or another. In fact, there's a good chance that many of the folks reading this article are on some kind of diet right now. There are all sorts of diets out there, but most of them have one basic thing in common -- in following the plan, you're required to watch the amount of calories you eat. A majority of diets also require you to avoid high-fat foods. There's one diet out there, though, that doesn't do this. Unlike its fellow regimen, it allows you to eat fairly large amounts of red meat, eggs, cheese, butter and even bacon -- all of which would be considered contraband on other plans.

Obviously there's a considerable amount of controversy over such a program; the Atkins diet, now known as the Atkins Nutritional Approach™, is a frequent topic among the media. While dieters across the nation are thrilled with the results of following this unorthodox plan, the medical community is fairly-well divided on how healthy an approach like this can be for someone -- especially in the long run.


Right now you're probably wondering how a diet like this could actually lead to weight loss. According to the late Dr. Atkins, it's all about limiting carbohydrates. As Americans, we eat a large amount of carbohydrates. These are foods that contain white flour and refined sugar. In other words, most of the packaged foods we eat such as pasta, bread and cereal are carbohydrate-rich. According to the core principle of the Atkins diet, by limiting carbohydrates in a four-phase process your body is forced to burn its stored fat, rather than carbohydrates, for fuel.

In this article we'll take a look at the general theory behind low-carbohydrate dieting. We will look at the four phases of the Atkins diet and what foods the plan allows you to eat. And finally, we'll discuss the benefits and drawbacks of the program and what medical experts have to say about it.


What is Low-Carbohydrate Dieting?

The late Dr. Atkins in his office at The Atkins Center for Complementary Medicine.
Photo courtesy Atkins®

In 1972, Dr. Robert Atkins first published his book, Dr. Atkins New Diet Revolution, which suggested a new way to diet. Up until this time, dieting consisted of lowering the number of calories eaten per day or lowering both the amount of fats and carbohydrates eaten. But, Dr. Atkins' diet was strictly focused on limiting carbohydrate consumption. So, what are carbohydrates?

You have probably heard of "carbohydrates" and "complex carbohydrates." They come in many forms including rice, pasta, bread, crackers, cereal, fruits and vegetables. Carbohydrates provide your body with its basic fuel. You can think about the relationship between your body and carbohydrates in much the same way you would consider the relationship between a car engine and gasoline.


The simplest carbohydrate is glucose. Glucose, also called "blood sugar" and "dextrose," flows in the bloodstream so that it is available to every cell in your body. Your cells absorb glucose and convert it into energy to drive the cell.

The word "carbohydrate" comes from the fact that glucose is made up of carbon and water. The chemical formula for glucose is:

You can see that glucose is made of six carbon atoms (carbo...) and the elements of six water molecules (...hydrate). Glucose is a simple sugar, meaning that to our tongues it tastes sweet. There are other simple sugars that you have probably heard of:

  • Fructose
  • Galactose
  • Lactose
  • Sucrose
  • Maltose

Glucose, fructose and Galactose are referred to as monosaccharides. Lactose, sucrose and maltose are called disaccharides (they contain two monosaccharides). Monosaccharides and disaccharides are called simple carbohydrates. When you look at a "Nutrition Facts" label on a food package and see "Sugars" under the "Carbohydrates" section of the label, these simple sugars are what the label is talking about.

There are also complex carbohydrates, commonly known as "starches." A complex carbohydrate is made up of chains of glucose molecules. Starches are the way plants store energy -- plants produce glucose and chain the glucose molecules together to form starch. Most grains (wheat, corn, oats, rice) and things like potatoes and plantains are high in starch. Your digestive system breaks a complex carbohydrate (starch) back down into its component glucose molecules so that the glucose can enter your bloodstream. It takes a lot longer to break down a starch, however. If you drink a can of soda full of sugar, glucose will enter the bloodstream at a rate of something like 30 calories per minute. A complex carbohydrate is digested more slowly, so glucose enters the bloodstream at a rate of only 2 calories per minute (reference). Complex carbs can be either high in fiber such as broccoli or low in fiber such as bananas or potatoes.

Carbohydrates are not the only substances the body uses for energy. The body also uses proteins and fats for fuel. Protein is contained in foods like red meat, poultry fish and cheese. Fats are also an important part of our diet. Many foods contain fat in different amounts. High-fat foods include dairy products like butter and cream as well as mayonnaise and oils. The idea behind low-carbohydrate dieting is to restrict the amount of carbs you eat and increase the amount of protein and fat. In other words, eating a low-carb diet would allow you to indulge in a cheeseburger but you must order it without the bun. Remember, bread contains carbs and the burger and cheese contain protein and fat. So, low-carb dieting is just what it sounds like -- you can eat protein and fat, but you must limit the amount of carbohydrates you eat.


The Four Phases of Atkins

Dr. Atkins walking on the beach on Long Island - The Atkins plan encourages integrating physical activity into your daily routine.
Photo courtesy Atkins®

The Atkins diet consists of a four-phase eating plan. The foods you eat vary depending on what phase you are in and your own personal metabolism. The four phases of the Atkins diet include:

  1. Induction - This is the first phase of the Atkins diet. It is also considered the most restrictive phase. In other words, phase one allows you to eat very little to no carbohydrates. You are limited to only 20 grams per day. The carbs you are allowed to eat consist of salad and other non-starchy vegetables.
  2. Ongoing Weight Loss - Phase two allows you to add some carbohydrates to your diet. In this phase, carbs are increased to 25 grams per day. Each week, you can increase the number of carbs you eat by five grams. So, the second week of phase two, you can have 30 grams of carbs. The third week you can consume 35 grams of carbs and so on. You continue on the course of slowly increasing carbohydrates until your body stops losing weight. When that occurs, you subtract five grams of carbohydrates from your daily intake. This level will allow you to maintain your weight.
  3. Pre-Maintenance - In this phase, you transition from weight loss to weight maintenance. You can increase your carbohydrate allowance by 10-gram increments each week as long as you continue to keep the weight off.
  4. Lifetime Maintenance - The final phase allows you to select from a wide variety of foods, while still limiting the amount of carbohydrates you eat. It is this phase that allows you to continue to keep your weight down as well as allows you to eat more foods than in the previous phases.


The Foods You Can Eat

The USDA Food Guide Pyramid
USDA Food pyramid courtesy Food and Nutrition Information Center

The USDA Food Pyramid recommends a diet rich in carbohydrate consumption. As you can see in the image below, the foundation of the pyramid is a recommended six to eleven servings of carbohydrates daily.

The Atkins food pyramid looks very different from this one. In fact, one of the reasons the Atkins diet was popular in the 1970s and has become popular again today is because it allows dieters to eat more of the foods most diets restrict or would never even allow -- such as red meat and high-fat dairy products like cheese and butter. According to the Atkins Web site, the Atkins plan helps people feel less hungry and less deprived than many other diets.


The Atkins Lifestyle Food Guide Pyramid™
Image courtesy Atkins®

Unlike the traditional food pyramid, the Atkins pyramid places dietary emphasis on protein sources as opposed to whole grain foods. Additionaly, the Atkins plan doesn't set limits on the amount of food you eat. It only sets limits on the type of food you eat. For example, you cannot eat white rice or foods made with white flour like cake or pasta, but you can eat a large amount of fish, poultry, red meat, eggs and cheese. These foods are made up mostly of protein and fat, as opposed to carbohydrates. Furthermore, Atkins is different from most diets in that you don't need to count calories. In fact, many people on Atkins consume more calories than they were before the diet (one gram of fat contains 9 calories, while one gram of any carbohydrate contains 4 calories).

Since the Atkins diet occurs in four phases, what you can eat will differ slightly in each phase. As you go through the phases, you are allowed more and more carbohydrates, but they should consist mostly of fiber-rich carbohydrates like leafy greens and certain vegetables. White rice, white bread, potatoes and pasta made from "white" or processed flour remain forbidden-foods for the duration of the Atkins plan. At this point, you may be asking yourself "How can someone lose weight on a diet like this?"

Let's examine how the Atkins plan can result in weight loss.


How Atkins Causes Weight Loss

A variety of Atkins products are available
Image courtesy Atkins®

As you now know, the Atkins plan begins by restricting carbohydrates. When your body is not given fuel in the form of carbohydrates, it uses fuel in other ways. So, let's say you've just started following the Atkins plan and are consuming a modest 20 grams of carbohydrates or less. Here is what's happening inside your body:

The liver stores glucose by converting it to glycogen. It holds perhaps a 12-hour supply of glucose in its glycogen. Once you finish digesting all of the carbohydrates that you last ate, the liver starts converting its stored glycogen back into glucose and releases it to maintain glucose in the blood. Lipolysis also starts breaking down fat in the fat cells and releasing fatty acids into the bloodstream. Tissues that do not need to use glucose for energy (for example, muscle cells) start burning the fatty acids. This reduces the glucose demand so that nerve cells get the glucose.

Once the liver runs out of glycogen, the liver converts to a process called gluconeogenesis. Gluconeogenesis turns amino acids into glucose.

The liver then begins producing ketone bodies from fatty acids being made available in the blood by lipolysis. Brain and nerve cells convert over from being pure consumers of glucose to partial consumers of ketone bodies for energy. This process is called ketosis -- which is why the Atkins plan is also known as a ketogenic diet.

So, what does this mean in simple terms? In theory, the Atkins diet enables your body to switch from a machine that uses carbohydrates for fuel to one that uses fat for fuel. Therefore, a diet with little or no carbs forces the body's storage of fat to become its main energy source.


To further understand the way your body loses weight on the Atkins diet, you must consider the way the body uses sugar as fuel. To turn sugars into fuel, your body uses the hormone insulin. Insulin enables our cells to turn carbohydrates into glucose by controlling the amount of sugar in our blood. The body secretes insulin to keep blood sugar from getting too high. Insulin is a storage hormone, meaning that it causes sugar we don't use for fuel to be stored as fat. It also keeps the body from burning stored fat. The Atkins diet suggests that it is this "insulin response" that continues to add fat to our bodies. This function is an asset when food is scarce, but an abundance of sugar-filled and high-carbohydrate foods will promote the accumulation of body fat.

On the contrary, a low-carbohydrate diet allows your body to release less insulin. According to the Atkins plan, when insulin levels are normal, your body will begin to burn its own fat as fuel; thereby resulting in weight loss. By keeping insulin levels stable, not only does your body burn fat, but it may also lead to less hunger and fewer cravings. Simply put, according to the Atkins folks, their diet attempts to control insulin levels by controlling the amount of carbohydrates you eat.


Benefits and Drawbacks

A sample menu following the Atkins plan. You can find recipes for each of these items at the Atkins Web site
Photos courtesy Atkins®

Now that you understand how the Atkins plan works, let's examine some of the benefits and drawbacks of low-carbohydrate eating. According to the Atkins Web site, there are four main benefits participants gain from following the Atkins plan:

  1. Weight Loss - When you cut down carbohydrates, your body converts from using carbohydrates for energy to burning fat as the primary energy source. This results in weight loss.
  2. Weight Maintenance - Each individual has a level of carbohydrate intake at which they will neither gain nor lose weight. The Atkins plan allows the body to determine this amount through the eventual increase in the amount of carbs you can eat.
  3. Good Health - Atkins dieters are encouraged to eat nutrition-rich foods with vitamin and nutritional supplements as needed.
  4. Disease Prevention - Lowering carbohydrate intake and, in turn, insulin production may help prevent diseases like diabetes.

The Atkins Web site also lists a few drawbacks to the diet. The two main drawbacks are bad breath, which is a result of excess ketone production, and constipation.


While some may consider the strictness of the diet a drawback, Atkins dieters are quick to point out that only carbohydrates are restricted - leaving a large selection of other food options.

And, unlike many other diets, for the most part the amount of food you eat has no restriction. Although, according to the Atkins plan, it's unlikely that you'll be overeating because:

  • Your cravings will be reduced
  • Protein-rich and high-fat foods are more satisfying and filling

The medical and nutritional communities have been increasingly concerned about some additional drawbacks to the Atkins diet. Many believe that the diet is a temporary fix for the permanent problem of weight loss. In other words, limiting carbohydrates to the degree the Atkins plan does, may be very difficult to maintain for many people. After all, the typical American eats a large amount of carbohydrates and the almost total elimination of this food group may not be something dieters can stick with for an extended amount of time.

Many medical groups have voiced concerns over the potential long-term health risks of the Atkins diet, such as kidney stones, ulcers and repeated kidney infections. Furthermore, in the past, research has shown that eating high levels of saturated fat -- as Atkins dieters often do -- may have negative health effects including increased cholesterol which can lead to heart disease and stroke.

Debates over the Atkins diet continue, and it would appear that the medical community is split on the issue. Let's take a closer look at what the experts are saying.



The Experts Weigh In

One of the many available books regarding the Atkins® program
Photos courtesy Atkins®

As mentioned earlier, there has been a great deal of controversy over the Atkins plan and other low-carbohydrate diets. The controversy generally revolves around the consumption of high-fat and high-protein foods, which are by and large believed to lead to heart disease and other ailments.

The controversy heated up when the Physician's Committee for Responsible Medicine (PCRM -- rumored to have ties to PETA) came out against the Atkins diet in December 2003 claiming that high-fat, carbohydrate-restricted diets lead to increased risk of chronic diseases and health problems. According to the PCRM's 2003 report, 429 people reported problems with high-protein, carbohydrate-restrictive diets. These ailments included kidney stones, heart problems (13 individuals reported heart attacks), gastrointestinal problems including ulcers and diarrhea and kidney infections. In fact, the American Academy of Family Physicians claims that high protein intake is largely responsible for the high prevalence of kidney stones in the United States.


However, critics of the PCRM data believe these studies cannot prove a cause-and-effect relationship between the Atkins diet and health problems. In fact, until recently, there has been little research into the long-term effects of the Atkins diet. It would appear that more studies will be needed to fully examine the effects of the Atkins plan and other low-carbohydrate diets. According to a recent report from ABC News entitled "Is the Atkins Diet Dangerous?", experts suggest that additional randomized, long-term studies are needed.

  • According to Dr. Arthur Frank, director of the George Washington University Weight Management Clinic in Washington, D.C., "Most of these diets are used by individuals for short times. The impact of any short-term intervention on heart disease is negligible. An important question is what happens for the long term."
  • Dr. Keith-Thomas Ayoob of Albert Einstein College of Medicine in New York states: I'd like to see a long-term study of at least 18 months, preferably two years, good compliance and follow-up to see what happens. These studies would monitor weight and cholesterol and track patients for adverse reactions such as heart disease and kidney problems.

According to another ABC news report, a new study published by the New England Journal of Medicine compared the weight loss of obese individuals on the Atkins diet versus traditional low-fat, low-calorie diets.

After one year, there was no weight difference between the groups. The Atkins group, though, did increase their HDL (the "good" cholesterol) levels. These results seem to suggest that the Atkins diet may not contribute to higher cholesterol levels even though the diet contains cholesterol-rich foods.

However, much of the medical community remains concerned about the increased levels of protein and fat consumed while following the Atkins plan. In addition to cholesteral levels and heart disease, they're also concerned about kidney function. An increased consumption of protein leads to an increase in ketones in the kidney. The increased level of ketones, or ketosis that occurs with the Atkins diet may be responsible for decreased kidney function. According to Harvard researchers, quoted in the PCRM study, individuals who consume large amounts of animal protein may be at risk for permanent loss of kidney function.

Regardless of the successful weight loss of people on the Atkins plan, doctors and nutritionists will continue to worry about the health effects of the diet. The PCRM Atkins Diet Alert suggests that carbohydrates are not necessarily responsible for weight gain. In fact, many people throughout Asia eat large amounts of carbohydrates and generally have lower body weights than Americans. Furthermore, many experts are quick to mention that carbohydrates are an essential part of the human diet.

In answer to this, Atkins supporters would point out that the Atkins plan limits carbohydrate intake, but does not eliminate it altogether. Although carbohydrate consumption is quite restricted during the "induction" and "ongoing weight loss" phases of the Atkins plan, progressively more amounts of carbohydrates, especially "good carbohydrates" like green, leafy vegetables and fruits, are allowed during the "pre-maintenance" and "lifetime maintenance" phases.

In the end, deciding to go on a diet, including the Atkins plan, is a personal decision. And, as is the case with any radical change in diet, it's a good idea to first discuss this with your physician.

For more information regarding the Atkins diet and related topics, check out the links on the following page.


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  • "Atkins for Life: The complete controlled carb program for permanent weight loss and good health" by Robert C. Atkins, M.D.