Keto vs. Atkins

Atkins and keto are the two best-known low-carb diets. Both stipulate an extreme reduction in high-carb foods, including sweets, sugary drinks, bread, grains, fruits, legumes, and potatoes.

The two popular diets drastically reduce carb consumption, but here’s how they stack up in terms of difficulty, safety, and results.

Though these diets are very much alike, they have differences as well.

The recommended daily carb intake for adults is about 200–300 grams (g) per day. The Keto and Atkins diets both involve a significant decrease in carbohydrate consumption. They also create similar effects on the body.

There are, however, differences in these eating plans. The differences affect the timing and extent of carb intake and specific effects on the body.

If both diets were ranked, the ketogenic diet and the Atkins diet would be neck and neck. “They both serve carbohydrate restriction,” says Erin Dolinski, RD, a clinical dietitian specialist at Beaumont Hospital in Royal Oak, Michigan.

We’re not just talking about reducing the bad-for-you carbs, but even things like fruit and some veggies. Limiting your carb intake puts the body into ketosis. This means the body turns to fat for fuel once its glucose stores are depleted.

Ketosis plays a role in each of the diets but in different ways, affecting how sustainable the diet is in the long run.

This article will compare and contrast the Atkins and Keto diets to help you decide which may be a better fit:

How the Ketogenic Diet Works?

There are a lot of moving parts with Atkins and its four phases. The ketogenic or keto diet, on the other hand, promotes one way of eating for the entirety of the diet.

As a result of eating this way for a few days, you will enter ketosis, which you can monitor with keto urine strips if you choose.

The keto diet was first developed in the 1920s to treat children with epilepsy, Dolinski says. Since then, research has linked the diet with weight loss. Hence, many people without a history of seizures hopped on the bandwagon.

A study published in November 2017 found that subjects who did the keto diet for ten weeks had notable changes in their weight, body fat percentage, body mass index (BMI), and HgA1c levels. 

Still, Dolinski advises the diet only for children with epilepsy. That’s because cutting out entire food groups and drastically changing the way you eat poses a fair amount of risk.

A growing body of evidence suggests the keto diet may help adults with epilepsy, too, but more research is needed in this population. If you have epilepsy, be sure to check with your doctor before making adjustments to your diet.

“The buildup of ketones can cause a lot of side effects, such as nausea, headaches, mental fatigue, and bad breath,” Dolinski says.

It can also lead to essential vitamin and mineral deficiencies. It can also increase your risk of kidney stones and potentially heart disease, depending on the types of fats people choose.

A person following the keto diet will eat very few carbohydrates, lots of fat, and some protein.

Below are the proportions of a person’s total daily macronutrient intake on the keto diet:

  • 70–80% fat
  • 20–25% protein
  • 5–10% carbohydrates

Carbs are the body’s go-to source of fuel. The keto diet involves significantly reducing carbs levels so that the body can no longer use them for energy.

When this happens, the body enters a state called ketosis, wherein the body starts to burn fats and produce ketones, which serves as a new energy source. For this reason, many people follow the keto diet as a way to burn body fat.

Keto diet enthusiasts recommend getting the carbs allowed from specific foods. This includes keto-friendly vegetables, such as leafy greens, and certain fruits, primarily berries.

How Does the Atkins Diet Works?

The Atkins diet was introduced in 1972 by a cardiologist named Robert Atkins, and it’s been popular on and off since Dolinski says.

The original version of the diet is called Atkins 20, and it has four phases. The introductory phase of the diet kicks it off with by far the most confining rules.

Like the keto diet, the Atkins diet permits few carbs, moderate amounts of protein, and high amounts of fat.

Over the years, the Atkins diet has developed to include various eating plans. 

According to the Atkins website, these 4 phases distinguished by the number of carbs that a person eats each day:

  • Phase 1 – This is the most restrictive phase, enabling just 20–25 g of carbohydrates per day. People stay in this phase until they are 15 pounds less from their ideal weight.
  • Phase 2 – During this phase, subjects can eat 25–50 g of carbs each day.
  • Phase 3 – This allows people to eat up to 80 g of carbs per day until they meet their goal weight and keep it for at least one month.
  • Phase 4 – Phase 4 is the maintenance phase, allowing 80–100 g of carbs per day.

The final phase is the least restrictive. The aim is to help a person be conscious of their carb intake and maintain a healthy weight.

During the first phase, the body enters ketosis, much like in the keto diet. As the person moves through the different stages, they begin to eat more carbs and more varied foods.

Protein and fat are fair game on Atkins, but carbs are strictly limited to between 20 and 25 grams (g) of net carbs (total carbs minus fiber) during the introductory phase.

Those carbs come from nuts, seeds, veggies, and cheese. “Having only that amount of carbohydrates can result in your body going into ketosis,” Dolinski says. You’ll stay in this phase until you’re about 15 pounds (lb) away from your objective weight.

Phase two raises the carb allotment between 25 and 50 g. This means you can add foods like blueberries, cottage cheese, and yogurt to your meal. You’ll stay here until you’re about 10 lb away from your objective weight.

During the third phase, you’ll increase between 50 and 80 grams of net carbs as you try to find that perfect balance. Simply put, how many carbs can you eat before the weight loss stalls?

“It is done slowly, realistically, with some trial and error to see what amount of carbohydrates can be consumed again without causing any weight gain,” says Michelle Jaelin, RD, a Hamilton, Ontario–based blogger at

Once you figure that out and maintain it for one month, it’s on to phase four: Lifetime Maintenance. This part of the diet focuses on continuing the habits developed during phase three. Carbs are allowed (up to 100 g per day), as long as the weight doesn’t creep back on.

Similarities Between the Keto and Atkins Diets

As they’re both low-carb diets, Atkins and keto are similar in some ways.

Phase 1 (Induction) of the Atkins diet is comparable to the keto diet, as it restricts net carbs to 25 grams per day. In doing so, your body likely begins ketosis and starts burning fat as its primary source of fuel.

What’s more, both diets may result in weight loss by reducing the number of calories you eat. Many carbs — particularly refined carbs like sweets, chips, and sugary drinks — are high in calories and may add to weight gain.

Both Atkins and keto require you to exclude these high-calorie, carb-rich foods so you can cut calories and lose weight with ease.

Will you reduce weight on a low-carb diet like these? Most likely, you will if you follow them rigidly.

Dolinski assumes that you’ll mainly lose water weight in the beginning because carbs retain water. She also believes that you’ll gain a lot of that back once you start eating normally again.

A study published in November 2014 in Circulation: Cardiovascular Quality and Outcomes found that after one year, people who followed Atkins lost a modest amount of weight (4.6 to 10.3 lb). However, some of the weight was regained by the end of year two.

You don’t have to count your calories on Atkins or keto. But you do need to track the number of carbs you take in. On keto, you also need to make sure you’re hitting the right percentages of calories coming from fat and protein.

As for which diet is more comfortable to follow, it depends on the person and his eating habits before starting the diet.

Unfortunately, neither of these diets will be easy to follow. That’s because low-carb diets can lead to dizziness, nutritional deficiencies, and mental and physical fatigue.

The Differences Between Keto and Atkins

Atkins and keto have individual differences as well.

One crucial difference between the keto diet and Atkins is the amount of protein you’re allowed to take in. There’s no cap on Atkins, while keto restricts protein to about 20 percent of your daily calories.

While keto is a moderate-protein approach, with about 20% of calories coming from protein, the Atkins diet permits up to 30% of calories from protein, depending on the phase.

Additionally, you want to keep your body in ketosis on the keto diet by restricting your carb intake.

On the other hand, the Atkins diet has gradually developed your carb intake, which will eventually kick your body out of ketosis.

Due to this flexible carb limit, Atkins allows for a wider variety of foods, such as more fruits and vegetables and even some grains.

The other big contrast is that keto centers on the body being in ketosis during the diet’s entire period. Meanwhile, ketosis plays a role only during phases one and two of Atkins.

On Atkins, you eventually reintroduce carbs, but on keto, carbs are always restricted.

Overall, Atkins is a less limiting approach, as you don’t have to monitor ketones or stick to specific macronutrient targets to stay in ketosis.

That means Atkins may be more sustainable in the long run because it’s not quite as limiting. It doesn’t require you to make sure your body remains in ketosis, either. Plus, on Atkins, you can eventually add back nutritious foods like quinoa, oatmeal, and fruit, the Atkins website notes.

Potential Health Benefits

Though once considered unhealthy, low-carb diets have now been shown to offer various health benefits.

A review published in the European Journal of Clinical Nutrition suggests that ketogenic diets protect the body from certain illnesses, such as cardiovascular disease and type 2 diabetes.

These benefits may reduce highly processed, high carb foods, and excess sugar in the diet.

There is emerging evidence these diets may help with other issues, such as acne and neurological disorders, although confirming this will require more research.

Weight loss

Low-carb diets can lead to more weight loss than other diet plans.

During a review of six popular diets, the Atkins diet resulted in the most weight loss after six months. A similar study found that it is the most likely to help lose weight after 6–12 months of following the diet.

Though more limiting than Atkins, the keto diet may aid weight loss as well. Studies indicate that being in ketosis decreases appetite, thereby removing one of the most significant barriers to weight loss — constant hunger.

Ketogenic diets also maintain your muscle mass, meaning that most of the lost weight is more likely to result from fat loss.

In one 12-month study, participants on a low-calorie keto diet lost about 44 pounds (20 kg) with few losses in muscle mass than the standard low-calorie group, which only lost 15 pounds (7 kg).

Moreover, the ketogenic diet maintains your resting metabolic rate (RMR) or the number of calories you burn at rest. In comparison, other low-calorie diets may cause your RMR to decrease.

Several studies have shown that these diets can result in weight loss, as the body burns fat very well when it enters ketosis. 

Most relevant studies show that a low carb diet results in significant weight loss than a low-fat diet. But in the longer term, these diets have similar weight loss results.

A small-scale study published in Diabetes & Metabolic Syndrome: Clinical Research & Reviews notes that ketosis may help manage obesity and metabolic risk factors that are precursors to type 2 diabetes. However, confirming these findings will require more research.

Blood sugar control

Research indicates that low-carb diets can benefit blood sugar control.

The American Diabetes Association recently revised the Standards of Medical Care. It is a document outlining how healthcare providers should manage and treat diabetes. This includes low-carb diets as a safe and effective option for people with type 2 diabetes.

Low-carb diets have been shown to decrease the need for diabetes medications and improve hemoglobin A1c (HgbA1c), a marker of long-term blood sugar control.

One 24-week study in 14 obese adults with type 2 diabetes on the Atkins diet found that participants lowered their HgbA1c levels and decreased their need for diabetes medications aside from losing weight.

Another 12-month study in 34 overweight adults noted that participants on a keto diet had lower HgbA1c levels, experienced more weight loss, and were more likely to discontinue diabetes medications than those on a moderate-carb, low-fat diet.

Other Benefits

Research suggests that low-carb, higher-fat diets may improve certain heart disease risk factors.

Low-carb diets may reduce triglyceride levels and increase HDL (good) cholesterol, thereby decreasing triglycerides’ ratio to HDL cholesterol.

A high triglyceride-to-HDL ratio is an indicator of poor heart health and has been linked to increased heart disease risk.

A review including over 1,300 people found that those on the Atkins diet had greater decreases in triglycerides, and more significant HDL cholesterol increases.

Low-carb diets have also been associated with other benefits, including improved mental health and digestion. Still, more research is needed.

Side Effects and Risks

Any diet that involves ketosis can cause adverse effects like bad breath, skin rashes, and “flu.” Staying in a state of ketosis for long periods can be harmful.

Also, people following either diet can develop nutrient deficiencies due to food restrictions.

For many people, carbohydrate sources are also vital sources of fiber. When reducing carbohydrates, people should get enough daily fiber from other sources, such as vegetables.

These diets may also increase the risk of deficiencies in electrolytes and many water-soluble nutrients that come from fruits and vegetables.

Finally, ketosis may help burn fat, but it may also lead to loss of muscle mass. Following a very low carb diet can result in a loss of muscle mass.

Which is Better?

Both Atkins and keto have benefits and downsides.

The ketogenic diet is too restrictive and may be challenging to stick to. Limiting your protein intake to 20% of calories while maintaining a very low carb and a very high fat intake can be challenging, especially in the long term.

Neither of these diets is recommended for people with chronic diseases like diabetes, heart disease, or kidney disease. But without any of those chronic situations, the diets can be safe if done short term.

The long-term safety of low-carb diets is a little uncertain. A study issued in February 2017 in BMJ Open Diabetes Research and Care looked at ten low-carb studies and found dropout rates varied from 2 percent to 60 percent.

What’s more, some people may feel the need to observe their ketone levels, which can be challenging and costly. Also, following a restrictive diet like the keto diet may lead to nutrient losses if you don’t pay careful attention to your diet quality.

Besides, there is limited evidence regarding the long-term safety or effectiveness of the keto diet. Hence, its long-term health risks are unknown.

Most people can reap some benefits from low-carb diets without being in ketosis. Therefore, moderate carb restriction on a low-carb diet like the Atkins diet is usually adequate instead of a strict keto program.

Overall, it’s most critical to focus on choosing healthy foods, regardless of the ratio of protein, fats, and carbs you eat. For example, higher-carb diets rich in plant foods, such as vegetables and fruits, are known to serve health in countless ways.

Though low-carb diets are healthy and safe for most people, it’s important to note that higher-carb diets that focus on whole foods are just as helpful.

Your weight loss goals, overall health, and dietary choices should all be considered when choosing the best eating pattern for yourself.

Final Thoughts

The word diet spelt out in vegetables on a wooden board.

Low-carb diets, particularly those focusing on high-quality, nutritious foods, can be beneficial. Be sure to talk to your doctor before making any drastic changes in your diet.

There are many comparisons to the keto and Atkins diets. Both require a significant decrease in calories from carbohydrates and support a person to get their calories from fats.

Atkins and keto are low-carb diets that may help with weight loss, diabetes management, and heart health.

Their main difference is that you slowly increase your carb intake on Atkins while remaining very low on the keto diet. Either way, it enables your body to stay in ketosis and burn ketones for energy.

Though some people may benefit from the more restrictive keto diet, a moderate carb restriction — like during the later phases of the Atkins diet — is enough for most to experience the benefits of a low-carb diet.

The keto diet puts more significant limitations on the source of calories. The Atkins diet starts very restrictive but becomes less so over time, enabling a person to eat a greater variety of foods.

Restrictive diets may support short term weight loss or fitness goals, but they may not be as healthful in the long term as other options.

Consult a healthcare provider before making any significant dietary changes. This is especially important for people with chronic health conditions.

When following any diet that eliminates food groups, make sure to avoid deficiencies by meeting daily nutrient needs in other ways.

Once a person reaches their target weight goals, it may be a good idea to switch to a less restrictive diet that incorporates a variety of nutrient-rich foods. Getting the right amount of daily physical activity can also help with maintaining a healthy weight.