Atkins Diet: What's behind the claims?

By Mayo Clinic Staff

What is the Atkins Diet?

The Atkins Diet is a popular low-carbohydrate eating plan developed in the 1960s by heart specialist (cardiologist) Robert C. Atkins. The Atkins Diet restricts carbs (carbohydrates) while focusing on protein and fats.

The Atkins Diet has several phases for weight loss and maintenance. It starts out with a very low-carbohydrate eating plan. The Atkins Diet is formally called the Atkins Nutritional Approach. It has been detailed in many books and is credited with starting the low-carb diet trend.

What is the purpose of the Atkins Diet?

The purpose of the Atkins Diet is to change your eating habits to help you lose weight and keep it off. The Atkins Diet also says it's a healthy lifelong approach to eating. It says it's a healthy approach whether you want to lose weight, boost your energy or improve health problems, such as high blood pressure or metabolic syndrome.

Why might you 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
  • Want a diet that restricts certain carbs to help you lose weight
  • Want to change your overall eating habits
  • Have medical concerns you think the diet can help improve
  • Like the related Atkins Diet products, such as cookbooks, shakes and bars

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

What does the Atkins Diet involve?

The main dietary focus of the Atkins Diet is eating the right balance of carbohydrates, protein, and fats for optimal weight loss and health.

The Atkins Diet notes that obesity and related health problems, such as type 2 diabetes and heart disease, are the fault of the typical low-fat, high-carb American diet. The Atkins Diet says that you don't need to avoid fatty cuts of meat or trim off excess fat. Rather, controlling carbs is what's important.

The Atkins Diet holds that eating too many carbs — especially sugar, white flour and other refined carbs — leads to many issues. The Atkins Diet says that it leads to blood sugar imbalances, weight gain and heart problems. To that end, the Atkins Diet limits carbs. The Atkins Diet encourages eating more protein and fat. But the Atkins Diet says it's not a high-protein diet.

Like many diet plans, the Atkins Diet keeps changing. It now encourages eating more high-fiber vegetables and has included changes to meet vegetarian and vegan needs. It also addresses health problems that may come up when first starting a low-carb diet.

Carbohydrates

The Atkins Diet doesn't require calorie counting or portion control. You do need to track your carbs, though. It uses a system called net carbs. Net carbs is the total carbohydrate content of an item minus its fiber content. For example, a half-cup (4 ounces) of raw broccoli has 2.3 grams of total carbs and 1.3 grams of fiber. This puts its net carb value at 1 gram.

The Atkins Diet says its approach to carbs will burn off your body's fat stores, control your blood sugar and help you achieve optimal health. And the Atkins Diet says it won't leave you feeling hungry or deprived.

Once you're at your goal weight, the Atkins Diet also explains it will help you find your personal carbohydrate balance. The personal carbohydrate balance is the number of grams of net carbs you can eat each day without gaining or losing weight.

Exercise

The Atkins Diet claims exercise isn't needed for weight loss. But it states that exercise can help keep your weight steady and offer other health benefits.

What are the 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. You eat just 20 grams of net carbs a day, mainly from vegetables.

    Instead of getting about half of your daily calories from carbohydrates, as recommended by most nutrition guidelines, you get only about 10%. "Foundation" vegetables, such as asparagus, broccoli, celery, cucumber, green beans and peppers, should account for 12 to 15 grams of your daily net carbs.

    In this phase, you eat protein, such as fish and shellfish, poultry, meat, eggs, and cheese, at every meal. You don't need to limit oils and fats. But you can't have most fruits, sugary baked goods, breads, pastas, grains, nuts or alcohol. You drink at least eight glasses of water a day. You stay in this phase for at least two weeks, depending on your weight loss.

  • Phase 2: Balancing. In this phase, you keep eating a minimum of 12 to 15 grams of net carbs as foundation vegetables. You also keep avoiding foods with added sugar. You can slowly add back in some carbs that are high in nutrients, such as more vegetables and berries, nuts, and seeds, as you keep losing weight. You stay in this phase until you're about 10 pounds (4.5 kilograms) from your goal weight.
  • Phase 3: Pre-maintenance. In this phase, you slowly keep increasing the range of foods you can eat, including fruits, starchy vegetables and whole grains. You can add about 10 grams of carbs to your diet each week. But you must cut back if your weight loss stops. You stay in this phase until you reach your goal weight.
  • Phase 4: Lifetime maintenance. You move into this phase when you reach your goal weight. Then you keep on with this way of eating for life.

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:

  • Breakfast. Egg-filled avocado with prosciutto. Acceptable drinks include coffee, tea, water, diet soda and herbal tea.
  • Lunch. Baby kale and blue cheese salad with hazelnut dressing, along with an allowable drink.
  • Dinner. Salmon and steamed artichoke with homemade lemon mayonnaise, along with an allowable drink.
  • Snacks. You typically can have two snacks a day. Snacks may include an Atkins Diet product, such as a chocolate shake or granola bar. Or you can have a simple snack such as celery and cheddar cheese.

What are the results of the Atkins Diet?

Weight loss

The Atkins Diet says that you can lose a large amount of weight in the first two weeks of phase 1 — but it also states that those aren't typical results. The Atkins Diet also notes that you may lose water weight at first. It says that you'll keep losing weight in phases 2 and 3 as long as you don't eat more carbs than your body can tolerate.

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 the Atkins Diet are no more effective for weight loss than are standard weight-loss diets. And studies find that most people regain the weight they lost no matter which diet plan they used.

Because carbs usually provide over half of calories consumed, the main reason for weight loss on the Atkins Diet is lower overall calorie intake from eating less carbs. Some studies suggest that there are other reasons for weight loss with the Atkins Diet. 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. Both of these effects also contribute to lower overall calorie intake.

Health benefits

The Atkins Diet says that its eating plan can prevent or improve serious health conditions, such as metabolic syndrome, diabetes, high blood pressure and heart disease. In fact, almost any diet that helps you shed excess weight can reduce or even reverse risk factors for heart disease and diabetes.

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 the Atkins Diet had improved triglycerides, suggesting better heart health. But there have been no major studies to show whether such benefits hold up for the long term or increase how long you live.

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.

But 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 two years or less.

What are the risks of the Atkins Diet?

The Atkins Diet says that cutting carbs extremely in the early phase of the program can cause some side effects, including:

  • Headache
  • Dizziness
  • Weakness
  • Fatigue
  • Constipation

Some very low-carb diets also restrict carbs so much that they cause you not to have enough nutrients or fiber. This can cause such health problems as constipation, diarrhea and nausea. Eating carbs that are high fiber, whole grain and high in nutrients can improve the health profile of programs like the Atkins Diet, though.

It's also possible that restricting carbohydrates to less than 20 grams a day — the level recommended for phase 1 of the diet — can result in ketosis. Ketosis occurs when you don't have enough carbohydrates that are broken down into sugar (glucose) for energy, so your body breaks down stored fat. This causes ketones to build up in your body. Side effects from ketosis can include nausea, headache, mental fatigue and bad breath.

In addition, the Atkins Diet isn't a good idea for everyone. For example, the Atkins Diet recommends that you talk to your health care provider before starting the diet if you take diuretics, insulin or oral diabetes medications. Also, people with severe kidney disease shouldn't follow the diet. And the weight-loss phases of the diet aren't a good fit for women who are pregnant or breastfeeding.

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May 12, 2022 See more In-depth