The Atkins diet: benefits, risks, and what to eat

There are a few certainties in life: death, taxes, and trendy ways to lose weight. At various times, dieters have been advised to count calories, avoid dietary fats, increase dietary fats, eat grapefruit, and the list goes on. Some popular diets have deservedly fizzled out, while others, like the Atkins diet, have lasted long enough to be influential today. Read on to learn more about the Atkins diet and its risks, benefits, and recommended foods.  

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The Atkins diet is named for Robert Atkins, a cardiologist who outlined the benefits of high-protein, low-carb diets in his 1972 book Dr. Atkins' Diet Revolution. It rose to popularity throughout the 1970s and challenged what at the time was conventional dieting advice to count calories and follow a low-fat eating plan. Atkins contended that reducing your intake of carbohydrates while emphasizing protein and fats could lead to more efficient weight loss. It's essentially the grandfather of the now-trendy ketogenic diet (keto diet).

There are four phases to the Atkins diet plan (Atkins.com, n.d.): 

• Induction: This phase involves limiting carbs significantly to 20 grams or less per day (with 12–15 grams of that coming from cooked vegetables or salad). It lasts two weeks.

• Balancing: During the balancing phase, you add 5 grams of carbs to your daily allowance each week, up to a total limit of 40 grams per day, including nuts, seeds, berries, and cheeses. 

• Pre-maintenance: You add an extra 10 grams of carbs per week (up to a max of 100 grams of carbs daily), including starchy vegetables, beans, more fruits, and whole grains. The goal is to determine your "carb balance" and goal weight. 

• Lifetime maintenance: Once you’ve reached your goal weight, you continue to eat at the carb level you find effective, potentially reducing your fat consumption slightly. If you gain weight, you're advised to drop your carb intake by 10–20 grams daily. 

There are three main variations on the Atkins diet—Atkins-20, Atkins-40, and Atkins-100, with the numbers standing for the number of net carbs allowed daily.

Because the Atkins diet is high in protein, which can provide more satiety than other macronutrients, it may encourage people to eat fewer calories overall, causing weight loss.  Often, people starting a high protein, low-carbohydrate diet notice rapid weight loss in the first two weeks—this is most likely due to a diuretic effect where some of that initial weight loss is water weight (Abassi, 2018).

Some of the recommendations in the Atkins diet plan—such as avoiding simple carbs and foods with added sugar and increasing your consumption of vegetables—may improve heart health. Studies show that low-carb, high-fat diets may promote weight loss, and improve blood sugar levels, especially in people with type 2 diabetes (Choi, 2020)

By cutting sugar and increasing low-carb vegetables, the Atkins diet may also affect your heart health. Some research suggests that following this diet may lower your risk of heart disease by raising your HDL cholesterol (i.e., “good” cholesterol) and lowering your triglycerides. However, other studies show an increase in total and LDL cholesterol, a risk factor for heart attacks and strokes (Choi, 2020). Experts are still unsure whether the Atkins diet provides long-term heart health benefits (Pallazola, 2019). 

Diets like Atkins, which encourage high protein and low carbohydrate intake, often cause your body to enter a state of ketosis. In ketosis, your body switches to a fat-burning mode where your liver converts fats into ketones. These ketones are then used as an energy source in place of carbohydrates (Abassi, 2018). 

While this sounds great in theory, it comes with risks. People following the Atkins diet may experience the “keto flu,” especially in the first few weeks. Symptoms of keto flu include (Masood, 2020):

• Nausea

• Vomiting

• Headaches

• Bad breath

• Fatigue

• Dizziness

• Problems sleeping (insomnia)

• Difficulty with exercise tolerance

• Constipation

Another downside of the Atkins diet previously mentioned is that it can raise your LDL cholesterol (i.e., “bad” cholesterol), potentially increasing your risk of heart disease (Choi, 2020). 

Lastly, restrictive diets are difficult to follow for extended periods and may make long-term weight loss hard to achieve. 

People often have questions about what foods/drinks they can eat on the Atkins diet. The answer depends somewhat on which phase of the diet you are currently following. Overall, the Atkins diet encourages you to create meal plans with a variety of foods that include meats, healthy fats like avocados and olive oil, low-carb vegetables, and full-fat dairy products. After Phase 1, you can add nuts, seeds, and some fruits to your meals.

Examples of acceptable foods to eat (Atkins.com, n.d.):

• Meats: beef, poultry, pork, fish, shellfish

• Dairy: eggs, full-fat milk, butter, Greek yogurt, cheese, other dairy products

• Fats: avocado, butter, mayonnaise, olive oil, vegetable oils

• Low-carb vegetables: leafy greens, olives, mushrooms, broccoli, cauliflower, tomatoes

• Fruits (after Phase 1): berries, cantaloupe, honeydew melon

• Nuts and seeds (after Phase 1): macadamia nuts, walnuts, almonds, sunflower seeds

The Atkins diet advises you to avoid high-carb foods like sugars, simple carbs, grains, and legumes—this is especially true during Phase 1 or the Induction phase. As you progress through the diet, you can add more foods to your repertoire.  

Examples of foods to avoid include (Atkins.com, n.d.): 

• Sugary foods: cookies, cakes, candy, soft drinks, juices

• High-carbohydrate vegetables: potatoes, yams, beans, corn, carrots

• High-carbohydrate fruits: apples, bananas, oranges, peaches, pears 

• Grains: white bread, pasta, rice, cereals

The Atkins diet is not for everyone, and you should consult with your healthcare provider before starting this or any other weight loss plan. Not every variation on the Atkins diet should be considered a long-term solution for weight loss. The most successful diets are flexible and less restrictive, and Atkins—the 20 and 40 variations, especially—may be difficult for some people to stick to.

Some people may need to take supplements while doing the Atkins diet to ensure their nutritional needs are met. You should avoid the Atkins diet, especially the more restrictive phases, if you are pregnant or breastfeeding. 

If you take insulin for diabetes or have kidney problems and choose to follow the Atkins diet, your healthcare provider may need to monitor you closely. High protein diets can affect your blood sugars and subsequent insulin dose, as well as your kidney function. 

The Atkins diet is not the only option out there—there is no “best diet” for weight loss. Several studies have shown that long-term weight loss of one year or more is the same in high-protein or high-carbohydrate diets, as long as they restrict calories (Gardner, 2018). The most important thing about losing weight is healthy eating while lowering your overall calorie intake and increasing your physical activity level (Rynders, 2019).

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Current version

July 27, 2021

Written by

Michael Martin

Fact checked by

Chimene Richa, MD

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About the medical reviewer

Chimene Richa, MD

Dr. Richa is a board-certified Ophthalmologist and medical writer for Ro.