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Atkins diet: What's behind the claims?

By Mayo Clinic staff

Definition

The Atkins diet is a popular low-carbohydrate weight-loss diet created in 1972 by cardiologist Robert C. Atkins. The diet, officially called the Atkins Nutritional Approach, has been detailed in many books and is credited with launching the low-carb diet trend. The Atkins diet is a commercial weight-loss diet, not a medical diet prescribed by your doctor.

The Atkins diet restricts carbohydrates while emphasizing protein and fats. Depending on the phase of the Atkins diet, you consume between 20 and 100 grams of carbohydrates a day. This is far less than the 225 to 325 grams per day recommended by the Institute of Medicine, which is why the Atkins diet is sometimes called a very low-carbohydrate diet.

Purpose

The Atkins diet aims to change your eating habits to help you lose weight and keep it off, and to help you live a healthier lifestyle and feel better.

Why you might follow the Atkins diet
You might choose to follow the Atkins diet because you:

  • Enjoy the types and amounts of food featured in the diet
  • Believe that a diet that restricts certain carbs will help you lose weight quickly or easily
  • Believe that you have blood sugar imbalances related to your current diet
  • Think that following this diet will help you achieve overall healthier eating habits
  • Think that you can stick with this diet for the long term
  • Like the related Atkins diet products, such as cookbooks, shakes and bars
  • Have friends who are doing the Atkins diet

Check with your doctor or health care provider before starting any weight-loss diet, especially if you have any health conditions, such as diabetes or kidney disease.

Diet details

The Atkins diet claims that obesity and related health problems, such as type 2 diabetes and heart disease, are the fault of the typical low-fat, high-carbohydrate American diet. The Atkins diet says that consuming excessive carbohydrates — especially sugar, white flour and other refined carbs — increases your insulin level, leading to blood sugar imbalances, weight gain and cardiovascular problems. To that end, the Atkins diet restricts carbohydrates and encourages higher consumption of protein and "good" fats. Like many diet plans, the Atkins diet has evolved over time — even since its founder died in 2003. It now takes a healthier approach, especially regarding consumption of dietary fats, suggesting, for instance, that you limit trans fats and saturated fats. Because some of the older Atkins diet books are still in print, they may not match the current Atkins diet advice.

The Atkins diet doesn't require calorie counting or portion control. It does require you to track your carbs, though. It uses a system called net carbs, which is the total carbohydrate content of an item minus its fiber content. For example, a half-cup of raw broccoli has 2.3 grams of total carbs and 1.3 grams of fiber, putting its net carb value at 1 gram.

The Atkins diet says its approach, called "controlled carbohydrate weight loss," will burn off your body's fat stores, regulate your blood sugar and help you achieve optimal health, while not leaving you feeling hungry or deprived. Once you're at your goal weight, the Atkins diet also says it will help you identify the number of grams of net carbs you can eat each day without gaining or losing weight, an amount called the "Atkins Carbohydrate Equilibrium."

Phases of the Atkins diet
The Atkins diet has four phases. Depending on your weight-loss goals, you can start at any of the first three phases.

  • Phase 1: Induction. In this strict phase, you cut out almost all carbohydrates from your diet, consuming just 20 grams a day. Instead of getting 45 to 65 percent of your daily calories from carbohydrates, as recommended by the Institute of Medicine, you get only about 10 percent. You focus on eating lean protein, such as poultry, fish, beef and eggs, and good fats, such as olive oil. You can also eat salad greens and low-starch vegetables, such as broccoli. You can't have sugary baked goods, breads, pastas, grains, fruits, nuts or alcohol. This phase claims to boost your metabolism. You stay in this phase for at least two weeks, depending on your weight loss.
  • Phase 2: Ongoing weight loss. In this phase, you add back in some nutrient-rich "good" carbs, such as more vegetables, cheese, berries, nuts and seeds, as you continue to lose weight. You typically eat between 40 and 60 grams of carbohydrates a day. As in phase 1, you focus on eating lean protein and good fats. You stay in this phase until you're within 5 to 10 pounds of your goal weight.
  • Phase 3: Pre-maintenance. In this phase, you deliberately slow down your weight loss as you learn a new way of eating that you can maintain for life. You can add about 10 grams of carbs to your diet each week, but you must cut back if your weight loss stops.
  • Phase 4: Lifetime maintenance. You move into this phase when you reach your goal weight and then you continue this way of eating for life. The Atkins diet says that most people can consume between 45 and 100 grams of carbs a day and maintain their desired weight. If you're fit and get at least an hour of exercise a day, you may be able to eat more carbs. In this phase, you achieve your Atkins Carbohydrate Equilibrium.

A typical day's menu on the Atkins diet
Here's a look at what you might eat during a typical day on phase 1 of the Atkins diet, according to the Atkins diet Web site:

  • Breakfast. One option is a Southwestern omelet with onions, peppers and ham. Beverages such as coffee, tea, water, diet soda and herbal tea are allowed in phase 1.
  • Lunch. Lunch might be a Caesar salad with poached salmon. You can have phase 1 beverages, plus side dishes if you stick to your daily carb allowance.
  • Dinner. A dinner option is chicken with rosemary roasted vegetables. You can have phase 1 beverages, plus side dishes if you stick to your daily carb allowance.
  • Dessert. The sample two-week phase 1 meal plan doesn't list desserts, but you can add them in as long as you meet your daily carb allowance.
  • Snacks. You generally can have two snacks a day. They may include an Atkins diet product, such as a chocolate shake or granola bar, olives, cheese, deviled eggs or sugar-free gelatin.

Results

Weight loss
The claim: The Atkins diet claims that you can lose 15 pounds (6.8 kilograms) in the first two weeks of phase 1 — but it also acknowledges that those aren't typical results. It says that you'll continue to lose weight in phases 2 and 3 as long as you don't eat more than your carb threshold.

The reality: Most people can lose weight on almost any diet plan that restricts calories — at least in the short term. Over the long term, though, studies show that low-carb diets like Atkins are no more effective than are standard high-carbohydrate diets and that most people regain the weight they lost regardless of diet plan. However, studies have shown that people who continued to follow diet plans such as Atkins for two years did lose an average of nearly 9 pounds (4.1 kilograms) overall. Some studies suggest that it's not cutting carbs that leads to weight loss with Atkins. Instead, you may shed pounds because your food choices are limited and you eat less since the extra protein and fat keep you feeling full longer. The bottom line is that to lose weight you must reduce the calories you take in and increase the calories you burn. Traditional recommendations for weight loss advise losing 1 to 2 pounds (0.45 to 0.9 kilograms) a week by reducing calories and fat and emphasizing complex carbohydrates. Losing a large amount of weight rapidly could indicate that you're losing water weight or lean tissue, rather than fat.

Health benefits
The claim: The Atkins diet claims that it can prevent or improve serious health conditions, such as diabetes, high blood pressure and cardiovascular disease. Atkins also claims that digestive problems such as heartburn, gallstones, gas and bloating will improve when you greatly reduce carbohydrate consumption.

The reality: Almost any diet can reduce or even reverse risks factors for cardiovascular disease and diabetes — if it helps you shed excess weight. And most weight-loss diets — not just low-carb diets — may improve blood cholesterol or blood sugar levels, at least temporarily. One study showed that people who followed Atkins had improved triglycerides, suggesting better heart health. But there have been no major research studies to show whether such benefits hold up for the long term or increase how long you live. Some low-carb or very low-carb diets restrict carbohydrate intake so much that they result in nutritional deficiencies or insufficient fiber, which can cause such health problems as constipation, diarrhea and nausea. Eating carbs that are high fiber, whole grain and nutrient dense can improve the health profile of programs like the Atkins diet, though.

Exercise
The claim: The Atkins diet says that exercise is a vital part of its approach. It also says exercise is important to maintaining weight loss and achieving other health benefits. And it disputes any notion that you can do the Atkins diet successfully without exercise.

The reality: Physical activity and exercise help you burn more calories, aiding weight loss. Regular physical activity is also vital to prevent regaining the weight you've lost and, of course, provides numerous health benefits. Although the Atkins diet says exercise is important, it doesn't specify how much you need. Healthy adults typically need at least 30 minutes of physical activity a day, according to the Department of Health and Human Services. However, if you're obese or you want to lose weight, you may need to increase your activity.

Risks

It's not known with certainty what risks, if any, the Atkins diet may pose to your health, especially over the long term.

Some health experts believe that eating a large amount of fat and protein from animal sources, as allowed on the Atkins diet, can increase your risk of heart disease or some cancers. However, it's not known what risks, if any, the Atkins diet may pose over the long term because most of the studies about it have lasted for a year or less.

In addition, the Atkins diet isn't appropriate for everyone. For example, Atkins warns that people with severe kidney disease should not follow the diet. It also cautions that the weight-loss phases of the diet aren't suitable for women who are pregnant or nursing. The Atkins diet recommends that you consult your doctor before starting the diet, especially if you have diabetes or gout or take diuretics, insulin or oral diabetes medications.

There are other risks associated with any commercial weight-loss diet:

  • If you skip a face-to-face evaluation with your health care provider, you may be unaware of important medical concerns.
  • The diet isn't tailored to your specific situation, including your weight-loss goals and any health conditions you might have.
  • A very restrictive menu may cause you to give up on your weight-loss goals.
  • You may not get enough fiber on low-carb diets, which may increase your risk of constipation, certain kinds of cancer and other digestive problems.
  • Unless you take a multivitamin or nutritional supplement, you may be at risk of certain nutritional deficiencies.
References
  1. Walker C, et al. Diets for cardiovascular disease prevention: What is the evidence? American Family Physician. 2009;79:571.
  2. Sacks F, et al. Comparison of weight-loss diets with different compositions of fat, protein, and carbohydrates. New England Journal of Medicine. 2009;360:859.
  3. Last AR, et al. Low-carbohydrate diets. American Family Physician. 2006;73:1942.
  4. Baron M. Fighting obesity: Part 1. Review of popular low-carb diets. Health Care Food & Nutrition Focus. 2004;21:1.
  5. Atkins two-week meal plan. Atkins. http://www.atkins.com/Program/FourPhases/WhatIsInduction/TwoWeekMealPlan.aspx. Accessed April 6, 2009.
  6. Phase 1: What is induction? Atkins. http://www.atkins.com/Phase1.html. Accessed April 6, 2009.
  7. Atkins RC. Dr. Atkins' New Diet Revolution. New York: Avon Books; 2002.
  8. Astrup A, et al. Atkins and other low-carbohydrate diets: Hoax or an effective tool for weight loss? The Lancet. 2004;364:897.
  9. Atkins RC. Atkins for Life. 2003. New York: St. Martin's Press; 2003.
  10. Malik VS, et al. Popular weight-loss diets: From evidence to practice. Nature Clinical Practice Cardiovascular Medicine. 2007;4:34.
  11. Dietary Reference Intakes (DRIs): Energy, Carbohydrate, Fiber, Fat, Fatty Acids, Cholesterol, Protein, and Amino Acids (Macronutrients). Institute of Medicine. http://www.nap.edu/openbook.php?isbn=0309085373. Accessed May 1, 2009.
  12. Hensrud DD (expert opinion). Mayo Clinic, Rochester, Minn. May 31, 2009.
  13. 2008 physical activity guidelines for Americans. U.S. Department of Health and Human Services. http://www.health.gov/paguidelines/pdf/paguide.pdf. Accessed Feb. 6, 2009.
  14. Carb counter: Vegetables. Atkins. http://www.atkins.com/Program/FourPhases/CarbCounter/Details36/Vegetables.aspx. Accessed May 1, 2009.

MY00648

July 16, 2009

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