The Atkins and keto diets are separate diets that both take a low carb, high fat approach to dieting. But you may be wondering what makes the two different from each other.

Atkins and keto are two of the best-known low carb diets.

Both require a drastic reduction in high carb foods, including sweets, sugary drinks, breads, grains, fruits, legumes, and potatoes.

Though these diets are similar, they have differences as well.

This article compares the Atkins and keto diets to help you decide which may be a better fit.

The Atkins diet is one of the best-known diets worldwide. It’s a low carb, moderate protein, high fat diet.

Though Atkins has evolved to offer a variety of plans, the original version (now called Atkins 20) is still the most popular. It’s broken down into four phases, which are based on your daily allowance of net carbs (total carbs minus fiber and sugar alcohols):

  • Phase 1 (Induction): This phase allows for 20–25 grams (g) of net carbs per day until you are 15 pounds (lb), or 7 kilograms (kg), from your goal weight.
  • Phase 2: During this phase, you consume 25–50 g of net carbs per day until you are 10 lb (5 kg) from your goal weight.
  • Phase 3: Your net carb allowance is raised to 50–80 g per day until you have met your goal weight and maintained it for 1 month.
  • Phase 4: During the final phase, you consume 80–100 g of net carbs per day for ongoing weight maintenance.

As you approach your goal weight and advance through these phases, your daily net carb allowance increases, allowing you to incorporate a greater variety of foods.

However, even during Phase 4, which allows for up to 100 g of net carbs per day, you consume significantly fewer carbs than most people usually eat.

The keto, or ketogenic, diet is a very low carb, moderate protein, high fat diet plan.

It was first used to treat children who experienced seizures, but researchers discovered that it may benefit other people as well.

The goal of the keto diet is to get your body into the metabolic state of ketosis, during which it uses fat rather than sugar from carbs as its main energy source.

In ketosis, your body runs on ketones, compounds that form during the breakdown of the fat from your food or the fat stored in your body.

To reach and maintain ketosis, most people need to limit their total carb intake to 20–50 g per day. Following the keto diet typically involves consuming less than 5% of calories from carbs, 10–30% from protein, and 65–90% from fat.

Some people monitor their ketone production using blood, urine, or breath tests.

Keto and Atkins have certain similarities but also differ greatly in some respects.

Similarities

Because they are both low carb diets, Atkins and keto are alike in some ways.

In fact, Phase 1 (Induction) of the Atkins diet is similar to the keto diet, as it restricts net carbs to 25 g per day. This will likely cause your body to enter ketosis and start burning fat as its main fuel source.

Phase 2 of the Atkins diet prescribes a carbohydrate intake of 25–50 g per day, which may also be low enough for many individuals to enter ketosis.

What’s more, both diets may result in weight loss by decreasing the number of calories you eat. Many high carb foods — particularly those containing refined carbs, such as sweets, chips, and sugary drinks — are high in calories and may contribute to weight gain.

Both Atkins and keto require you to eliminate these high calorie, carb-rich foods, which makes it easier to cut calories and lose weight.

Differences

Atkins and keto have certain differences as well.

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

Additionally, on the keto diet, the goal is to keep your body in ketosis by extremely limiting your carb intake.

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

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

Overall, Atkins is a less restrictive approach, as you do not have to monitor ketones or stick to certain macronutrient targets to stay in ketosis.

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

Weight loss

Low carb diets may result in more weight loss than other diet plans.

A 2014 review of six popular diets, including Atkins, the Zone Diet, the Ornish diet, and Jenny Craig, found that Atkins resulted in the most weight loss after 6 months.

A similar 2017 study found that Atkins was the most likely of 7 popular diets to result in meaningful weight loss 6–12 months after starting the plan.

Though it is more restrictive than Atkins, the keto diet may aid weight loss as well. Research indicates that being in ketosis decreases appetite, thereby removing one of the biggest barriers to weight loss — constant hunger.

Ketogenic diets may also preserve your muscle mass, meaning that most of the weight loss you may experience is more likely to be a result of fat loss.

In one 2014 12-month study, participants on a low calorie keto diet lost about 44 lb (20 kg) with few losses in muscle mass, while those on a standard low calorie diet lost only 15 lb (7 kg).

Additionally, ketogenic diets maintain your resting metabolic rate (RMR), the number of calories you burn at rest, whereas other low calorie diets may cause your RMR to decrease.

Blood sugar regulation

Research indicates that low carb diets can benefit blood sugar regulation.

In fact, the American Diabetes Association recently revised the Standards of Medical Care — a document outlining how healthcare professionals should manage and treat diabetes — to include 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 levels of hemoglobin A1c (HgbA1c), a marker of long-term blood sugar regulation.

One 2013 24-week study in 14 adults with obesity and type 2 diabetes who were on the Atkins diet found that in addition to weight loss, participants experienced a decrease in HgbA1c levels and a decreased need for diabetes medications.

Another 2017 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 the ratio of triglycerides 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 2016 review including more than 1,300 people found that those on the Atkins diet had greater decreases in triglycerides and more significant increases in HDL cholesterol than individuals following a low fat diet.

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

Both Atkins and keto have benefits and downsides.

The ketogenic diet is extremely restrictive and may be difficult 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.

Some people may also feel the need to monitor their ketone levels, which can be challenging and costly.

Following a restrictive diet like the keto diet may lead to nutrient deficiencies if you do not pay careful attention to your diet quality.

Additionally, evidence on the long-term safety or effectiveness of the keto diet is limited, so its long-term health risks are unknown.

Most people can reap several of the benefits of low carb diets without being in ketosis. Therefore, moderate carb restriction on a low carb diet like the Atkins diet — as opposed to a strict keto approach — is usually sufficient.

Overall, it’s most important 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 benefit health in countless ways.

Though low carb diets are healthy and safe for most people, higher carb diets that focus on whole foods are just as beneficial for health as low carb, high fat diets.

It’s important to consider your weight loss goals, overall health, and dietary preferences when choosing the best eating pattern for yourself.

Low carb diets, particularly those focusing on high quality, nutritious foods, can be beneficial. However, be sure to consult a healthcare professional before making any drastic changes to your diet.

Atkins and keto are both low carb diets that may benefit weight loss, diabetes management, and heart health.

Their main difference is that you gradually increase your carb intake on Atkins, while it remains very low on the keto diet, allowing your body to stay in ketosis and burn ketones for energy.

Though some people may benefit from the more restrictive keto diet, moderate carb restriction — such as in the later phases of the Atkins diet — is sufficient for most people to experience the benefits of a low carb diet.