Atkins 40® Diet Facts

Understanding the Atkins 40 Diet in full is important before beginning. Learn the basics to start your weight loss journey with us today.

Q: What is the Atkins Diet?

The Atkins Diet® is the original leading low-carb weight loss plan that provides quick, effective, satisfying and balanced weight loss based on an extensive body of scientific research. The Atkins Diet is designed to “flip the body’s metabolic switch” from burning carbs to burning fat. Graduated carb introduction limits blood sugar and insulin spikes, which cause hunger and cravings, and result in overeating and weight gain.


  • Atkins has the additional application of being the weight loss plan of choice for the millions of people who have a reduced ability to process carbohydrates – those who have varying levels of “carbohydrate intolerance.” The Atkins 40 plan allows you to start the Atkins program with 40 grams of Net Carbs. This means you can eat from all food groups on the acceptable foods list from all four phases from day one on the program, and still enjoy the weight loss success on a fat burning metabolism.
  • On Atkins 40 you will eat:
    • More vegetables than the USDA recommends
    • Proteins including meats, fish, poultry and plant-based proteins
    • Healthy fats including olive oil, avocado and nuts
    • Dairy including whole Greek yogurt, as well as hard and soft cheeses
    • Variety of fruits and whole grains

Q: Does this mean people can consume a little sugar and still lose weight?

We do not recommend consumption of added sugar on Atkins 40, as it has an immediate impact on blood sugar and offers little nutritional benefit compared to other foods allowed in the daily 40g Net Carb intake. Those who chose the Atkins 40 plan will use the acceptable foods lists from the Atkins 20 plan from all four phases.

Q: What data did you use to determine the efficacy?

We evaluated 31 clinical studies and concluded that a low-carb diet of 40g Net Carbs per day can maintain ketosis ( fat burning) and be an effective weight-loss program, as well as improve other health markers such as triglyceride, HDL, glucose and insulin levels.

Q: Why are some of the portions so small (ex. one Atkins-serving of whole wheat bread or quinoa)?

Some items on the acceptable food list for Atkins 40 are higher in carbohydrates and lower in fiber than others, and Atkins therefore recommends smaller serving sizes of those foods, in order to maximize nutritional benefits of your 40g net carb intake.

Q: How is this different than Phase One of the Atkins plan?

Atkins 40 focuses on eating foods at 40g Net Carbs and offers an extensive food list, as well as focuses on portion control. Phase One, also known as Atkins 20, starts you out at 20g of Net Carbs.

Q: Are any foods still off-limits?

Atkins 40 dieters should continue to avoid/limit added sugar and refined carbs such as white flour, which are low in nutritional value. In addition, dieters should avoid foods that act as “triggers” for them, personally (i.e. foods that cause unhealthy cravings and temptations).

Q: Will I still be able to lose weight quickly?

As 40g Net Carbs has been scientifically validated as an acceptable level for the body to begin burning fat as fuel (i.e. ketosis), most individuals will still be able to lose weight at a healthy pace following Atkins 40.

Q: What is the difference between a low-carb diet and a low-fat diet?

Carbs and fat are your body’s two sources of fuel. A low-fat diet is high in carbs, so when you eat more carbs than your body needs, it stores them as fat. Atkins is an effective diet that transforms your metabolism from one that stores fat into one that burns fat. High carbohydrate diets raise blood sugar, which in turn signals the body to secrete more insulin—you wind up with more fat on your body and a “sugar burning” metabolism. The Atkins diet restricts foods that are known to raise blood sugar and insulin. Limiting carbohydrates forces your body to use fat for energy rather than sugar.

Q: I’ve been following the traditional Atkins Diet, now called Atkins 20 – should I switch to Atkins 40?

There are some things to consider before you jump to Atkins 40.

Reasons to continue following Atkins 20:

  • You have more than 40 pounds to lose
  • You are pre-diabetic or diabetic
  • Your waist circumference is higher than 40 inches for men, 35 inches for women
  • You are content with food choices being re-introduced gradually, in pre-defined order
  • You are seeing positive results with Atkins 20 (“If it isn’t broke, don’t fix it!”)


Reasons to consider moving to Atkins 40:

  • You have less than 40 pounds to lose
  • You are not pre-diabetic or diabetic
  • Your waist circumference is less than 40 inches for men, 35 inches for women
  • You are pregnant or nursing
  • You are currently on Atkins 20, and looking for more variety in food choices

Q: How do I get back on track after an “indiscretion”?

First of all, don’t beat yourself up. We all have moments of weakness, and maybe that plate of French fries your friend was eating was more than you could resist. Second, don’t play the game of “Well, since I’ve already messed up, I might as well go whole hog.” For the rest of the day, eat appropriately. Don’t wait until tomorrow to get back on the wagon.

Q: How can individuals following Atkins 40 ensure they are getting a fully balanced, nutritional diet?

  • Atkins is founded on the principles of optimal protein intake, adequate healthy fat intake, and low carbohydrate consumption. Individuals experience success on Atkins by restricting carbohydrates to a level that allows the body to burn fat for fuel. For most people, fat burning or nutritional ketosis is achieved when a low carbohydrate (on average under 50g/day for the majority of adults) and moderate protein (about 100g/day or 4 to 6 ounce per serving) diet is followed for more than 3 days.
  • The scientific evidence for the Atkins low carbohydrate program continues to build and evolve in the past two decades. Results reported in independent peer review journals have consistently demonstrated robust health outcomes and better weight loss. More than 80 peer-reviewed, scientific studies back the low carbohydrate nutritional approach.
  • The Atkins Diet includes a wide variety of foods throughout the entire plan and encourages the consumption of a healthy balance of nutrient dense food, adequate protein, a full array of high-fiber vegetables, low glycemic fruits, whole grains, and healthy fats. It teaches every individual to discover their own perfect carbohydrate balance.

Q: In addition to weight loss, what are some of the health benefits associated with the Atkins Diet?

Independent third-party clinical research has found that the Atkins Diet reduces risk factors for heart-disease, insulin resistance, diabetes, and improves inflammation markers.


By eating carbohydrates in moderation, the Atkins Diet helps individuals (even those without diabetes) maintain stable blood sugar levels, leading to fewer carb cravings and more energy, among other health benefits. Scientific research has consistently found that subjects at a high risk for Coronary Artery Disease (CAD) that were following the low-carb approach had improvements in their cholesterol profiles, decreasing their risk of developing CAD.


There are also many digestive benefits that come with following Atkins. Fiber requirements can be easily met because the Atkins Diet replaces highly refined, low-fiber carbohydrates with salad greens, fresh vegetables, low sugar fruit, nuts, seeds and whole grains. The diet includes lots of vegetables to replace processed foods, which increases fiber intake. A high-fiber diet is the best way to lower risk factors associated with the colon. Additionally, numerous scientific studies have confirmed that those eating a high-fiber diet have lower cholesterol levels and fewer incidences of heart disease than those on a low-fiber diet.


With its ability to help you lose weight, improve your lipid profile and blood pressure, increase your energy and reduce your risk of heart disease, diabetes and many other life-threatening conditions, the Atkins Diet is indeed a healthier, more balanced way of eating and living.

Q: Can vegetarians or vegans follow the Atkins Diet?

The Atkins Diet allows individuals to consume a wide variety of foods, all framed within a context of eating fewer carbohydrates and sugars. The diet can be followed as a vegetarian or vegan. Vegetarians can start in Phase 2 of Atkins 20 at 30 grams of Net Carbs and introduce seeds and nuts before berries. Vegetarians will can get their protein from eggs, nuts, dairy, and soy products. Vegans can start in Atkins 40 at 40 grams of Net Carbs so they can have nuts, seeds as well as legumes from the start. Vegans can get sufficient protein from seeds, nuts, soy products, soy and rice cheeses, seitan, legumes and high protein grains like quinoa.

Q: It is common knowledge that Atkins limits carb intake, but does the diet allow for individuals to eat any carbs?

Those following the Atkins 40 plan will need to choose foods from the acceptable food lists. Atkins offers a well-balanced way of eating that incorporates foods from all major food groups – it does not include high sugar items like cakes or candy.


If someone follows the Atkins40 plan, they will have a wider variety of food choices from the beginning, from all rungs of the carb ladder. Their daily carb intake is 40g of net carbs per day, 12-15g coming from foundation vegetables, and the remaining net carbs can be budgeted to small portions of higher carb foods (i.e.: legumes, whole grains, fruit) or low-carb products. When someone is 15 pounds from their goal weight, they can increase their intake to 50g NC per day.

Q: Isn’t Atkins criticized for having too much fat?

Atkins does focus on fat, but a balance of fats that are commonly agreed to be healthy, such as monounsaturated fats like olive oil and avocado as well as naturally occurring saturated fats and polyunsaturated fats. If they wish, although not necessary, individuals can easily avoid saturated fats while on Atkins by following the plan as a vegetarian.


It is important to remember that if carbohydrate levels are low, fat intake needs to be higher. When the body is in fat-burning (aka ketosis), it uses fat from our food intake and body fat for fuel. As you increase your carb level, the amount of fat consumed will naturally decrease, and protein levels remain constant throughout the diet.


Research from more than 80 peer-reviewed independent studies has consistently demonstrated the diet’s safety and efficacy.

Q: Is it dangerous to lose weight very quickly?

When you start the Induction phase of Atkins, you may experience rapid weight loss for the first time in your life. Don’t worry. What makes the initial drop dramatic is that you lose a good bit of water weight in the first 3 to 4 days. That’s because eating fewer grams of carbohydrate results in fewer spikes in blood sugar, resulting in less insulin output. Insulin makes the body retain sodium, which, as you probably know, makes your body retain water. When you’re not producing as much insulin, this cycle slows. After four days or so, however, you will also begin to lose body fat. Young men and people who have a lot of weight to lose are more likely to lose weight more rapidly at the start of the Atkins program.


Losing weight too fast is an issue only if:


1) You’re not eating enough, which could make you lose lean muscle mass. To lose only body fat, be sure to eat regular meals and take in adequate calories. If you aren’t hungry at meal times, have a small snack with your supplements. Also, drink at least 64 ounces of water every day.


2) You feel sick, weak, dizzy or fatigued. If you lose too fast, especially at the beginning of the program, you may be experiencing an extreme diuretic effect. This could deplete you of water and also some electrolytes, which contain sodium, potassium, calcium and magnesium. Signs of electrolyte depletion are muscle cramps and heaviness in your legs when climbing steps. You may need to add more vegetables to your meals to slow down weight loss and add a mineral supplement to replace lost minerals.


But if you feel well and aren’t starving yourself, you’re probably not losing too quickly.

Q: What is “Carbohydrate Intolerance” and Metabolic Syndrome?

Atkins offers a scientifically proven plan that delivers increased weight loss and health marker improvements among those who have carb intolerance. The Atkins Diet reduces carbs to begin weight loss, and then directs the dieter to increase their healthy carb intake until they find their perfect carb balance – the level where their body can effectively metabolize carbs and maintain their weight long term. No other weight loss plan does this.


Only a doctor can make a medical diagnosis of carb intolerance, but there is a simple way to spot the first indicator: waist measurement. Fat deposited at the waist is a particularly unhealthy type of fat (visceral fat), and increased amounts of visceral fat can be indicative of carb intolerance. Women with waist sizes greater than 35 inches and men with waist size greater than 40 inches should consider speaking with their doctors about carb intolerance. It is important to note that this is a simple guideline and health risks can vary with height and body type.

Q: I'm used to counting calories. How many am I allowed on the Atkins Diet?

The Atkins Nutritional Approach counts grams of carbohydrates instead of calories. However for weight loss purposes we suggest you shoot for a healthy range. For women that range is approximately 1500 to 1800 calories. For men that range is approximately 1800 to 2200 calories per day. Be sure to limit empty calories and follow the acceptable foods list.


Research has shown that on a controlled carbohydrate program, more calories are burned than on a low-fat, high-carbohydrate diet, so there is a certain metabolic advantage to the controlled carb approach. But understand that this does not give you a license to gorge.


The real goal of the Atkins program is to learn eating habits that will enable you to permanently maintain a healthy weight and lifestyle. This includes changing old habits such as overeating that contributed to your original weight problem.

Q: I lost weight for the first few months, but now the scale just won't budge. How do I get off this plateau?

First, before you assume there is a problem, ask yourself some questions: Are you feeling better? Are your clothes fitting better? (You may be losing inches, not pounds, because muscle is more dense than fat.) Are you still losing, but at a slower rate? You may just need to continue a bit longer, making slight modifications. These include:

  • Decreasing the number of grams of carbohydrate you are consuming by 5 or 10 grams.
  • Increasing the amount of fat and decrease protein if you are consuming more than 4 to 6 ounces per serving.
  • Finding and eliminating “hidden” carbs in the form of processed foods that may contain sugar.
  • Increasing your activity level.
  • Drinking at least eight 8-ounce glasses of water daily.
  • Look at which higher-carb foods you’ve consumed recently, and eliminate for a week. Perhaps you have a food sensitivity.

Q: How is the Atkins Diet beneficial to those who have been diagnosed with type 2 diabetes?

Yes, a type 2 diabetic can overcome high blood sugar using Atkins since the diet helps regulate blood sugar. Protein, fat, and low-carb vegetables have the least effect on blood sugar, which means they will not cause very high blood sugar. However, if an individual is on blood sugar lowering medications, they need to work closely with their doctor to adjust medication dosage. The need for medication diminishes dramatically and quickly while on Atkins.

Q: What is carb creep and how can I avoid it?

The great thing with Atkins 40 is that you have a wide variety of food choices to pick from, including starchy vegetables and whole grains so you don’t feel deprived. However, you want to be sure you’re keeping portion sizes in check especially when you’re eating those foods to avoid carb creep. On the website, we’ve provided a list of 5g and 10g net carb serving sizes of many of your favorite foods so you know what is appropriate.

Q: What is the highest level of carbohydrate consumption per day recommended for Lifetime Maintenance?

The important concept to understand in order to maintain your weight is finding your personal carb balance. You should find the highest level that won’t allow you to regain weight or cause hunger and cravings. Each person has a personal carb balance, and a bit of trial and error may be required for you to find yours.

Q: Can I drink alcohol now following Atkins 40??

The body burns alcohol for fuel when alcohol is available. So when it is burning alcohol, your body will not burn fat. This does not stop weight loss; it simply postpones it. Since the alcohol does not get stored as glycogen, you immediately get back into fat burning after the alcohol is used up. If it does not slow your weight loss, an occasional glass of wine is acceptable, so long as you count the carbohydrates in your daily tally. (A 3 1/2-ounce glass of wine contains about 4.3 grams of carbohydrate.) Spirits such as Scotch, rye, vodka and gin are acceptable, but do not mix with juice, tonic water or non-diet soda, all of which contain sugar. Seltzer, diet tonic and diet soda mixers are permitted. If you have added alcohol to your regimen and suddenly stop losing weight, discontinue your alcohol intake.

Q: I have been able to do Atkins successfully but now that I’ve been following it for a while, my appetite increased. Why and what can I do to manage it?

Appetite can return when you are no longer in lipolysis (fat burning). Or you may have added a food that may be causing your blood sugar to become unstable, contributing to hunger or the re-emergence of cravings. Examine what you’ve recently added and determine if it contains sugars or refined grain. Be sure that you are maintaining a regular intake of protein and fat and, if eating more of acceptable foods assuages your hunger, eat a bit more. If all else fails, stop the most recent additions until you get your appetite under control.

Q: What types of products and support does Atkins offer?

Atkins provides dieters with a wide variety of products, tools and support.  Atkins: Eat Right, Not Less: Your Guidebook for Living a Low-Carb and Low-Sugar Lifestyle, the all-new Atkins guidebook focuses on eating right—not less—for painless weight management and better overall health. Choose the program that works for you: Atkins’ classic approach (Atkins 20®), a better keto diet (Atkins 40®), or small changes that lead to big results (Atkins 100™).

The New Atkins for a New You and New Atkins Made Easy books provide readers with guidelines on how to follow the diet. A cookbook hit the stands in 2011 and is entitled The New Atkins for a New You Cookbook: 200 Simple and Delicious Low-Carb Recipes in 30 Minutes or Less.

Atkins also offers a variety of frozen meals, nutrition bars and shakes which can serve as a convenient meal, snack, or treat. Some of these products are indulgently sweet but low in carbs – so Atkins dieters can indulge their sweet tooth while managing hunger all day. They can be purchased at major retail stores or at Additionally, Atkins offers a free online community and resource center at with more than 1,600 recipes and menu plans, as well as shopping lists for each phase of the plan. Community Members get all the resources and support to complete the diet online for FREE at – other diets can cost upwards of $30 per month. Upon registration, a quick-start kit is available for FREE on to give dieters all the information they need to get started.

Q: How do Artificial Sweeteners Inhibit Weight Loss?

For many people artificial sweeteners can be a sensitivity that can cause slower weight loss or stop weight loss altogether. Everyone is different and may have different sensitivities. If you encounter a stall or plateau in weight loss, evaluate how much artificial sweetener you are consuming, and try reducing.

Q: What is the most up to date Atkins Diet book?

The Atkins® 100 Eating Solution Easy, Low Carb Living for Everyday Wellness.  Our newest book by Colette Heimowitz dives into the Atkins 100 program, making it easy for anyone to stick to 100 net carbs a day while enjoying every meal and getting real results. With cutting-edge research and 50 delicious recipes, The Atkins 100 Eating Solution provides an exciting, mouthwatering variety of food, and also explains the Atkins 20 and 40 programs, including low carb cooking and eating out hacks. Whether you’re looking to lose weight, manage an illness through diet, or simply feel better in your body, The Atkins 100 Eating Solution is here to help.

Atkins: Eat Right, Not Less: Your Guidebook for Living a Low-Carb and Low-Sugar Lifestyle by Colette Heimowitz focuses on eating right—not less—for painless weight management and better overall health. Choose the program that works for you: Atkins’ classic approach (Atkins 20®), a better keto diet (Atkins 40®), or small changes that lead to big results (Atkins 100™).

Q: Where do I find Articles/Data regarding the Atkins Diet?

To find more information regarding articles or data supporting the Atkins Diet, please visit our SCIENCE and LIBRARY tabs. If you’re looking for information to share with your physician, please direct them to our Healthcare Professional Portal,