The Atkins diet has gone through significant changes since it was first introduced in the 1960s by Robert Atkins, M.D., a cardiologist. The current program allows you to choose from different eating styles based on your weight loss or health goals. Atkins 20 and Atkins 40 are described as keto diets by the company. Ketogenic diets limit carbohydrate intake so that your body burns fat as fuel.

Weight loss is likely to occur on the Atkins plan, especially during the more restrictive phases of the program. According to the company, an average person can expect to lose 1–2 pounds per week on the plan. Some people who are already at a healthy body size might use the Atkins program to maintain their weight or boost health.

What Experts Say The Atkins diet is a carbohydrate limiting weight loss diet. Health professionals agree limiting fiber-rich food groups can lead to constipation and nutrient imbalances. A focus on counting carbohydrates prompts eating by numbers instead of exploring individual likes and needs.

—Willow Jarosh, MS, RD

Background

The Atkins diet is probably the most widely recognized low-carb diet plan. It was developed by New York City cardiologist Dr. Robert Atkins in the 1960s as an alternative to the use of amphetamines for appetite suppression and weight loss. Prior to the publication of his first book Dr. Atkins' Diet Revolution in 1972, Dr. Atkins and several of his colleagues tried the diet themselves and experienced substantial weight loss.

Since its beginning, the Atkins approach to eating has garnered substantial controversy because nutrition experts advised higher carbohydrate diets that limited fat. The Atkins plan was commonly known as diet that allowed you to eat foods high in saturated fat like bacon, butter, and ground beef. Many critics were concerned about the long-term effects of this eating style on heart health.

Over the years, Dr. Atkins refined his approach as new research about diet and nutrition became available. The Atkins diet still focuses on limiting carbohydrates but offers consumers different intake levels for consumers based on their health goals. They are also advised to make nutritious food choices including healthy fats, fiber-rich carbohydrates, and a wide range of protein sources such as seafood, beef, and poultry.

People think of the Atkins diet as primarily a weight loss diet,﻿﻿ but some people also use the eating program hoping to control blood glucose, reduce blood pressure, or to gain other health benefits.

One of the main goals of the diet is to help each individual find the optimal amount of carbohydrate for that person's body

How It Works

The Atkins diet plan relies on knowing how much carbohydrate is in everything you eat. Specifically, consumers count their net carbs. Net carbs can be calculated by checking the total grams of carbohydrate in your portion of food and subtracting the grams of fiber and sugar alcohols or glycerin (if applicable).

There are three Atkins programs based on different levels of net carb intake per day. The company recommends that you check with your healthcare provider for personalized advice before choosing a program to manage a medical condition.

Atkins 20

The Atkins 20 plan is what most would consider to be the classic Atkins plan. It is designed for those who have over 40 pounds to lose, have a waist size of over 35 (for women) or 40 (for men), are pre-diabetic, or diabetic.

People on this program start by consuming just 20 net carbs per day. They eat a variety of approved (foundational) vegetables, lean meat, cheese, and healthy fats to meet their energy needs. After two weeks on Atkins 20, people on this plan can begin to add berries, nuts, and other fiber-rich carb sources in five net carb increments. Then gradually they learn to incorporate more healthy carbohydrate choices to reach and maintain their goal weight.

There are four phases to the Atkins 20 program:

Induction Phase . For two weeks or longer, consumers keep their net carbs at the lowest level.

. For two weeks or longer, consumers keep their net carbs at the lowest level. Balancing Phase. People on the program slowly add grams of net carbs to find the best carbohydrate balance.

People on the program slowly add grams of net carbs to find the best carbohydrate balance. Fine Tuning Phase . Clients are advised make small tweaks to reach and maintain their goal weight for at least a month.

. Clients are advised make small tweaks to reach and maintain their goal weight for at least a month. Lifetime Maintenance. You continue to eat a healthy diet with limited carbohydrates to maintain your goal weight.

Atkins 40

This plan offers a more relaxed program where dieters eat from all food groups from day one. The plan is designed for people who have 40 pounds or less to lose, those who prefer a wider variety of food choices, or for women who are breastfeeding with a goal to lose weight.

On this program, you start the first phase of the plan by consuming 40 grams of net carbs per day from vegetables, fruits, nuts, legumes, and whole grains. As dieters approach their goal weight, they add carbs in 10 net carb increments to find their personal carb "sweet spot" to maintain their healthy weight.

Atkins 100

This is the most relaxed Atkins eating program. It is designed for those who want to maintain their current weight, who prefer the widest variety of food choices, or for women who are breastfeeding and have a goal to maintain weight. The company also suggests this program for women who are pregnant as long as they have approval from their healthcare provider.

On this plan, you consume about 100 grams of net carb per day with no foods that are off limits.

On each of the Atkins plans, net carbs are to be divided between three meals and two snacks per day so that blood sugar remains stable throughout the day. You don't count calories on these programs, but portion size recommendations are provided. Additionally, it recommended that certain foods (such as added fats) are limited.

Pros and Cons

Consumers who choose to go on an Atkins eating plan are likely to see some weight loss and health benefits.

For many people, restricting carbohydrates means eliminating heavily processed, high-sugar, high-starch foods which contribute calories without substantial nutrition.

If you replace those less healthy foods with more nutritious foods (such as those on the Atkins Acceptable Foods lists), you are likely to increase your intake of important micro and macronutrients.

On the flip side, however, if you currently consume a standard American diet, adjusting to an Atkins plan may be challenging, especially if you choose to go on the Atkins 20 plan. Typically, people consume most of their calories from carbohydrate. Cutting back on carbs can lead to symptoms including headaches, fatigue, mood swings, and constipation.

Additionally, even though you don't have to count calories on the Atkins diet, you do need to count carbs, calculate net carbs and balance carbs between meals and snacks. You'll also need to use food lists to make sure you're consuming foods that are compliant. For many busy people, this work may seem overwhelming. As an alternative, consumers can choose to purchase an Atkins meal plan and get pre-packaged meals, smoothies, and snacks.

Common Myths and Questions

Myth: You don't eat any fruits or vegetables on the Atkins diet.

Non-starchy vegetables are encouraged on the Atkins eating plan. On the most restrictive phase of Atkins 20 (Phase 1) consumers are advised to consume 12–15 grams of net carbs from foundational vegetables per day. These vegetables include greens like spinach, arugula, and kale and other colorful veggies such as bell peppers, eggplant, radishes, artichokes, and many others.

Starting with Phase 2 on Atkins 20 and on Atkins 40 and Atkins 100, fruits are included in the plan including higher-fiber choices such as berries, honeydew, and cantaloupe.

Myth: You need to eat a lot of red meat and cheese when you're on Atkins.

Meat is not required on the Atkins plan. If you prefer not to eat meat at all, you can follow the vegetarian program. But if you follow the traditional plan, many types of protein are encouraged. For example, fish, poultry, shellfish, and eggs are encouraged. Cheese is also on the acceptable foods list but Atkins recommends consuming no more than 3–4 ounces per day. Processed meats with nitrates are not recommended.

Myth: You lose the most weight during induction.

Induction is another name for Phase 1 of the Atkins 20 plan. This phase is believed to be the most effective phase for weight loss. However, you generally don't stay on this phase of Atkins. Most people who follow the program will move on to the "balancing" phase or Phase 2.

During induction, you are likely to lose substantial water weight because your body doesn't need to hold water to store carbohydrate. So while you may see a substantial change on the scale, this weight isn't necessarily fat loss. Weight loss during the other stages is estimated to be at a rate of one to two pounds per week.

How It Compares

While the Atkins diet was a novel approach to weight loss when it was first introduced, there have been quite a few similar diets established in the years since Dr. Atkins' book was first published in 1972. Low carb eating has become one of the most common approaches to weight loss, wellness, and weight maintenance. However, the program still differs substantially from USDA recommendations.

USDA Recommendations

The macronutrient balance of the Atkins diet varies substantially from guidelines provided by the US Departments of Agriculture and Health and Human Services. The 2015-2020 Dietary Guidelines for Americans suggest that an adult who consumes a 2,000 calorie per day diet should consume 130 grams of carbohydrates per day.﻿﻿

On the Atkins diet, you consume fewer than 50 grams of carbohydrate per day. Carb intake varies on the plan you choose and clients can tailor their carb intake to meet their health goals on the Atkins 100 plan. But you can expect to consume substantially more fat, slightly more protein and fewer carbs than recommended by the 2015-2020 Dietary Guidelines for Americans.﻿﻿

Ketogenic Diet

On a traditional ketogenic diet, you can expect to consume less than ten percent of your total calories from carbohydrate.﻿﻿ This is one of the primary factors that makes keto diets exceptionally hard to maintain. In addition, on a keto diet, you might count total carbs rather than net carbs.

On the Atkins plan, your carb intake is still low but it is usually higher than on a traditional keto eating plan. On Atkins 20 you start by consuming five percent to 10 percent of your total calories from carbohydrate. On Atkins 40, you begin by consuming 10 percent to 15 percent of your total calories from carbs.

Paleo Diet

On this low-carb eating plan, you eat a diet similar to the one consumed by our prehistoric ancestors. Since grains were not available to these pre-agricultural, hunter-gatherer ancestors, you won't consume any traditional carbohydrate foods, like bread, pasta, or cereal grains.﻿﻿ This keeps the carb count very low. Instead, you eat meat (preferably grass-fed), seafood, fruits, vegetables, eggs, nuts/seeds, and healthy oils.

While the program sounds similar to Atkins, the plans differ in that the more recent versions of the Atkins plan provide serving sizes and suggested intake amounts. For example, they suggest that you keep meat and seafood portions to 4–6 ounces.

Also, on the Paleo diet, you don't consume any processed foods (such as microwavable foods or packaged smoothies). Customers who choose one of the Atkins meal plans will consume many of their meals in this form.

South Beach Diet

Like the Atkins diet, the South Beach Diet was developed by a physician (Dr. Arthur Agatston) who was trying to help his patients lose weight. It also has stages during which you stick to different calorie or macronutrient guidelines.﻿﻿

On South Beach, Phase one allows you to consume about 1,000 calories per day. Of that, about 25 percent to 35 percent of your calories will come from carbohydrate—more than is allowed on Atkins. Fat intake begins at 30 percent to 40 of total calories (lower than Atkins) and then increases to 40 percent to 45 percent of total calories.

Like Atkins, they encourage their customers to choose less processed foods and they provide suggested portion sizes. South Beach also provides a complete diet meal delivery service for a monthly membership fee that includes microwavable foods and shakes.

A Word From Verywell

While the Atkins diet has gained acceptance from many in the nutrition and health communities, some are still worried that the diet is too restrictive to maintain for the long term. Additionally, high saturated fat intake is still a concern—with some studies indicating no relationship to heart health and others still showing a negative effect.

If you choose to try the Atkins diet, speak with your health care provider and talk about how your intake of carbohydrates and fat might change on the plan. Based on your health history and current status, your medical provider can make personalized suggestions about whether or not the program is likely to be healthy for you and modifications that you might make to make the diet more manageable.