Atkins Diet vs. Keto Diet: What is the Difference?

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Written by Brenda Peralta, Registered Dietitian and medically reviewed by Abby Courtenay

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If you are looking to lose some weight, a common go-to solution is the ketogenic diet. Although keto is the most popular diet today, in years past people used to follow the Atkins diet for the same purpose.

So, what is the difference between keto and Atkins? Are they safe to follow? What are the pros and cons of following each one? What foods are allowed in each?

Although the two eating styles are very similar, since both are low-carb, high-fat diets, there are important differences that make each one unique.

If you are wondering which one is more effective, or which is more compatible with your lifestyle, keep reading to find the best option for you.


What is the Atkins diet?

The Atkins diet is a low-carb way of eating created by the physician Dr. Robert C. Atkins in 1972. It was created for people who are looking to lose weight.

The Atkins diet has been optimized over the years. There are different macronutrient ratios on the Atkins diet depending on how much weight you want to lose. The main difference is the carb ratio. Protein usually stays around 20-30% of your total daily intake, and the fats account for 70-90%. Carbs are divided into three categories.

  • Atkins 20. Less than 20 g of total net carbs.
  • Atkins 40. 40 g of total net carbs.
  • Atkins 100. 100 g of total net carbs.

Atkins 20 has four different phases. At the start, you greatly reduce your carb intake. As time goes on, you increase the number of carbs you consume.

  1. Phase 1. 20-25 g of net carbs per day. You can eat healthy fats, protein, most cheeses, and low-carb veggies. This usually lasts at least two weeks, or until you have only 15 pounds (7 kg) to lose to reach your goal.
  2. Phase 2. Increase the carb intake to 25-50 g per day. You can start adding other products like cherries, melon, berries, plain Greek yogurt, whole milk, legumes, and tomato juice. This phase lasts until you have only about 10 pounds (4.5 kg) more to lose.
  3. Phase 3. Increase the carb intake to 50-80 g per day. You can now add starchy vegetables, other fruits, and whole grains. This lasts until you achieve your goal.
  4. Phase 4. Increase the carb intake to 80-100 g per day. This is the final phase, and you stay here as a permanent lifestyle.

The main focus of Atkins is that it doesn’t rely on counting calories but on only counting carbs. However, on average, they have 1,500-1,800 kcal meal plans for women and 1,800-2,000 kcal for men.

Can you eat keto and Atkins at the same time?

No, you can’t. Although they have a similar base of being low-carb and high-fat diets, you really cannot follow both at the same time.

Atkins slowly starts increasing the carb intake and focuses mainly on protein intake rather than fats. On keto, you keep carbs consistently low and focus on eating fats.

Since they have different macronutrient compositions, you can’t follow them together.

If you wanted to combine them, you could do keto first, then transition to Atkins and slowly increase your carbs.


Similarities between Atkins and keto diets

How are keto and Atkins related? Let’s find out!

Carb limit on atkins and keto

The exact carbohydrate intake depends on the Atkins phase you are in and the type of keto you are doing. However, the carb limit is always very low.

Carb limit (grams of net carbs) Phase 1: 20-25 g
Phase 2: 25-50 g
Phase 3: 50-80 g
Phase 4: 80-100 g
Less than 50 g


Even though the Atkins diet slowly increases the carbs slowly, 100 g of carbs per day is still considered low-carb. Most people eat around 50% carbs, which would be about 250 grams (or 220g net carbs) for the average person consuming 2,000 daily calories.

Weight loss

Both diets are commonly used to lose weight. Since they are low-carb, they induce a ketosis state. This means that you end up using your fat reserves for energy. In both cases, you can see dramatic weight loss.


For bodybuilding, both are excellent options for those that are looking to shed some fat mass. If you are in a cutting phase, either one of these diets could be a good fit..

If you are in a bulking phase, you could potentially achieve weight gain. However, since fat and protein are more filling, it might be more challenging to reach the total daily caloric intake for a bodybuilder in a bulking phase. This can reach 3,000 calories or even more.

Type 2 diabetes

Thanks to their ability to induce ketosis, both can be options for those trying to handle type 2 diabetes. For people who have a hard time reducing their carb intake, following either keto or Atkins can be a good way to decrease sugar levels.

Remember to always speak with your healthcare provider before making any special diet changes.

Atkins or keto for inflammation

For both diets, there are several studies on their relationship with inflammation. Being in a ketosis state seems to reduce inflammation in the body. (Both ways of eating use ketosis.)

Also, both eliminate high-carb sugary foods like candy, sugar, cakes, pastries, and refined grains. This, in the end, leads to reduced inflammation.

However, following traditional Atkins, where there is a focus on saturated fats and protein, might not be the best for reducing inflammation. In that case, keto may be better for reducing inflammation than Atkins

Atkins has added modifications over the years, so it may be possible to follow a healthier version.


Differences between keto and Atkins

Now that you know the similarities shared by both diets, let’s look at the ways they differ.

Compare keto and Atkins macros amount

While both carb intakes are very low, there is a difference with the protein intake. Atkins prefers a high-protein approach, with 20-30% of total daily calories from proteins.

Keto, on the other hand, prefers a moderate protein approach. Typically, it recommends having no more than 20% of total calories dedicated to this macronutrient.

The fat intake can be a little bit lower in the Atkins, depending on the protein intake. Fat could range from 60-70%, while on the keto, it is usually higher at 70-80%.

The macros for the keto diet stay the same over time. You calculate your macros and stick to them. 

In the Atkins diet, this is not the case. As seen above, there are four different phases to go through, with the total carb intake increasing over time.

Types of foods allowed

Although it has changed its approach to foods, the traditional Atkins diet emphasizes the consumption of high-fat meats. This means that the saturated fat intake was higher than normally recommended (no more than 10% of the total daily calories).

The keto diet recommends healthy fats from unsaturated sources like nuts, seeds, olive oil, olives, and avocados. It also emphasizes using whole, natural ingredients for clean eating and reducing your intake of ultra-processed foods.

Atkins vs. keto for epilepsy

The traditional ketogenic diet is used by doctors as an effective treatment for epilepsy for both children and adults. This is why the diet was first created, before people realized its potential for weight loss.

The Atkins diet is not traditionally used to treat epilepsy. There is a modified Atkins sometimes used for these cases, but it was not originally intended for this purpose.


Benefits of the ketogenic diet and Atkins

Because both promote a ketosis state, they have similar advantages. Here is a list of the benefits you can get from following a low-carb and high-fat diet.

  • Weight loss. This is the most common benefit and the main reason why people follow these diets.
  • Improved insulin sensitivity.  Having a lower carb diet can have a positive impact on insulin, making it work better in your body.
  • Decreased appetite. Due to the increase in fats (and in some cases protein), these ways of eating provide more satiety. This means you are less likely to be hungry during the day even when calories are decreased.
  • Decrease intake of highly processed foods. Since most highly processed foods are carbs, they are reduced in both diets since the daily carb wouldn’t allow it.
  • Improved symptoms of PCOS. Some women have had success using these diets to alleviate this condition.
  • Reducing the risk of seizures. Thanks to ketones, there is a decrease in the incidence of attacks in many people with epilepsy. *If you have epilepsy, chat to your doctor before changing your diet, there are specific circumstances where a ketogenic diet is recommended in these patients).


Side effects of Atkins and keto

You can get similar disadvantages from the Atkins or the keto diet, mostly due to the low-carb intake. Here are the most common risks.

  • The low-carb “flu”. During the first few days, while your body adapts, you may experience fatigue, foggy brain, nausea, and decreased performance.
  • Constipation. Due to the low carb intake (where fiber comes from), there might be a risk of getting constipation. Make sure you eat enough fiber (at least 25 g per day) and have a good water intake.
  • Highly restrictive. Some people may find it challenging to maintain this eating pattern, especially during social gatherings. Although now there are more low-carb options available on the market, you should be aware of the possibility you may feel excluded or nervous about explaining your needs to friends and family.
  • Low nutrient intake. Since veggies and fruits can be lowered, there is an increased risk of having nutrient deficiencies. Make sure to eat the rainbow. This means adding different colorful veggies into your daily life.


Foods to eat on Atkins and keto

Even if they are similar, there are different foods that are allowed in one and not the other.

Since Atkins has different phases, this also affects which types of foods you can eat.

Remember that this is a guideline for you to use. As long as you have variety and manage to keep your carb intake below the recommended amount in both diets, you can include almost any type of food in moderation.

Beans and legumes Allowed
Not allowed Allowed
Condiments and sauces Allowed
Dairy Allowed
(high-fat diary like cream & hard cheeses)
Sugar-free drinks Allowed Allowed Allowed
Sugar-sweetened beverages Not allowed Not allowed Not allowed
Alcoholic drinks Allowed
Not allowed Allowed
Eggs Allowed Allowed Allowed
Fish and seafood Allowed Allowed Allowed
Fruits Allowed
Not allowed Allowed
Grains and starches Allowed
Not allowed Allowed
Herbs and spices Allowed Allowed Allowed
Meat and poultry Allowed Allowed Allowed
Nuts and seeds Allowed Allowed Allowed
Oils and fats Allowed Allowed Allowed
Processed foods Limited 
(low carb)
(low carb)
(low carb)
Sugar-free sweeteners Allowed Allowed Allowed
Natural sweeteners Allowed
White and brown sugars Not allowed Not allowed Not allowed
Starchy vegetables Allowed
Not allowed Allowed
Non-starchy vegetables Allowed Allowed Allowed


This table gives you a summary of which foods to eat according to the diet you are following. You can see that they are very similar with a few differences.

If you have any questions on which foods are keto, you can search for them in the index of keto-friendly foods. Other resources are available to check whether or not you can eat certain foods, and how much.


Atkins versus keto cost

The cost of each diet is very similar. The cost of them depends on your personal choices. For example, if you choose more premium types of meat cuts or buy them organic, the price tag will be bigger.

If you buy local and look for products that are in season, there shouldn’t be a big difference in buying more veggies to add to your diet.

There might be a slight cost increase on the Atkins diet since it requires you to eat more protein, which can be more costly. However, if you choose low-cost meats, this shouldn’t be a significant difference.


Which diet is healthier, keto or Atkins?

Thanks to the adaptations made throughout the years on both diets, they can both be great options for someone looking to follow a low-carb lifestyle.

As long as you eat lots of vegetables and focus on including more unsaturated fats like peanuts, flaxseeds, salmon, olive oil, and olives, doing either Atkins or keto can be a healthy choice.

If you opt to do the Atkins diet, try to increase your protein intake with lean protein instead of fatty proteins like bacon (there is nothing wrong with adding it once in a while).


Bottom line

Both can be effective low-carb diets to follow for weight loss. If you don’t want to feel so restrictive, following the Atkins diet might be the one for you since it has slightly more carbs.

Remember to also add more color variety to your fruits and veggies. Try to have the goal of having at least three different colors during the day. The more, the better, but try to reach at least 3. That way, you get different nutrients.