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Keto vs. Atkins Diet: Same Theory, Different Approach

The Keto diet and the Atkins diet are similar in many ways — here's how to decide which one you should do.


As of 2024, there are two highly popular low-carbohydrate, high-protein, and high-fat regimens in the world of diets: the keto diet, and the Atkins diet. Both promote weight loss and are seemingly quite similar from the outside, however, they aren’t identical in terms of restrictions, cost, long-term impact, and more. In fact, when you compare keto vs. Atkins, there are a number of key differences that might encourage dieters to pick one or the other.

Vicki Koenig, MS, RD, CDN of Nutrition Wise explains the differences and similarities to Woman’s World. She says although each are similar in theory, they are executed very differently: “Keto is ‘simple’ in that you focus on protein from primarily meat sources, fats, and get a small amount of carbs from non-starchy veggies. It promotes fat burn, so you can lose weight,” she explains.

“Atkins works in four phases of carb restriction. It starts low like keto, slowly increasing carbs after you’ve lost the desired amount of weight and are ready to maintain. It requires calculating grams of carbs in common foods. keeping track of how much is consumed.”

How Keto vs. Atkins Stacks Up

Keto DietAtkins Diet
Cost Per Year$2,444, according to Finder$4,319, per Finder
RestrictionsCarbohydrates; refined sugars; protein surplusCarbohydrates for phases 1 &2; refined sugars
AvailabilityExpenses/less refined ingredients make it less availableExpenses/less refined ingredients make it less available
How It Makes Dieters FeelSymptoms of keto flu possible, but otherwise energizedSatisfied; sometimes initial sluggishness in phase one
Calories Per Day1,500 to 1,800 for women; 1,800 to 2,200 for men1,500 to 1,800 for women; 1,800 to 2,200 for men
Cheat DaysNot recommended — can bring the body out from ketosisOne “cheat night” per week on Atkins is OK
Effectiveness Short-TermInitial weight loss is quick, but unpleasant keto flu symptoms may occurEffective for short-term weight loss, along with possible symptoms such as constipation, headaches, dizziness and more
Effectiveness Long-TermCan be tricky to stick to; can help with weight loss and blood pressure; long-term health impact unknown Can help with weight loss long-term, though large amounts of fat can contribute to heart disease
Side EffectsKeto flu: headache, dizziness, moodiness, body aches, bad breathSimilar to keto flu — constipation, headaches, halitosis, weakness, fatigue

Related: The Atkins Diet: Behind the Staple Weight Loss Plan

Keto Is All About No Carbohydrates, and a Ton of Fat

Sliced butter on a plate
Butter is a beloved high-fat, keto-friendly ingredient.GYRO PHOTOGRAPHY/Getty Images

As previously mentioned, the keto diet is a low-carbohydrate, high-fat diet. The regimen has drawn in many dieters over the last decade or so, thanks its quick weight loss results as well as the “tasty” high-fat food it permits.

After a Few Days, the Body Goes Into Ketosis When It Starts Burning Fat — Not Carbs

Upon eliminating carbohydrates, starches, and refined sugars, dieter’s bodies are sent into “ketosis.” A Cleveland Clinic explainer on the diet describes ketosis as the body’s transition from burning carbohydrate storages to burning through fat storages.

Ketosis Comes With Positive and Negative Side Effects

While going into ketosis makes some feel energized, others have reported feeling symptoms of what’s known as the “keto flu.” This is characterized by moodiness, fatigue, dizziness, indigestion, and headaches. Dieters may also experience bad breath, and intense cravings.

The Short-Term Results Are Often Note-Worthy

The keto diet can result in quick short-term weight loss. A piece about what a week on keto looks like from Healthline shows that keto dieters can expect to lose a pound or more after just seven days. Studies have also shown that it’s helped people experiencing obesity with their blood sugar levels, as well as waistline circumference.

However, There Are Physical Drawbacks to the Keto Diet

A woman sits on the couch with a hand on her head in pain
The keto diet can come with unpleasant side effects, including headache and fatigue.Vladgans/Getty Images

Fast results are generally touted as “the goal” for most diets, however, there are some disadvantages. An analysis of the risks from the University of Chicago warns dieters that following keto long-term can cause heart disease, kidney stones and other health problems.

There Can Also Be Mental Health Drawbacks

The keto diet can take a negative toll on one’s mental health. A diet as restrictive as keto may lead to disordered eating. Because it eliminates so many foods while giving “positive” results, it often gives people the idea that they should be constantly restricting. Additionally, because the results are often quick with a plateau long-term, many resort to yo-yo dieting.

Related: The Keto Diet Explained: Is the Popular Weight Loss Regimen Effective?

Atkins Is All About Phasing Out Carbohydrates, and Phasing Them Back In

The Atkins Diet is was created in 1972 by cardiologist Robert Atkins, who wrote a best-selling book claiming that carbs contribute to poor heart health. That’s when he decided to create the Atkins, which the Mayo Clinic defines the diet as a low-carbohydrate diet.

It largely focuses on protein and fat intake, and is divided into four “phases.” Phase One eliminates carbohydrates entirely, and as it continues, it introduces more carbohydrates back into the diet.

The Most Significant Results Come During Phase One

A bowl of chinese purple spinach
Phase One of the Atkins diet consists of many leafy greens.Brian Yarvin/Getty Images

Phase One, or the “Induction” phase, is the most restrictive. An explainer from Healthline notes that dieters generally see the most results during Phase One, as it primarily consists of leafy greens and protein. Then, moving forward is effectively maintenance.

However, people can choose to stick to Phase One as long as they want (or as long as is advised by their doctor). After that is Phase Two (Balancing), Phase Three (Fine-Tuning), and Phase Four (Maintenance). Each introduces more grains, nut, and fruits.

Atkins Diet Has Both Negative Short- And Long-Term Impacts

A study published to PubMed Central looks at the controversy behind the Atkins Diet, highlighting negative impacts, both short- and long-term. One short-term impact is symptoms similar to the “keto flu.” By transitioning to burning fat instead of carbohydrates, dieters may feel symptoms of dizziness, headaches, fatigue, nausea, constipation and bad breath.

Long-Term, Atkins Can Cause Serious Health Problems

An elderly woman suffering from chest pain in bed.
Longterm, Atkins can contribute to heart problems.Milko/Getty Images

Science also shows that a low-fiber diet that doesn’t prioritize carbohydrates can lead to gastrointestinal and lung cancer. Meanwhile, the high amounts of fat one is encouraged to consume while on the diet can contribute to various heart issues.

Atkins May Also Promote Negative Mental Health Effects

Similar to the keto diet — or any other restrictive diet — Atkins can have some negative mental health effects. The restriction can lead to disordered eating, while the initial weight loss in Phase One may lead to yo-yo dieting.

Comparing Keto vs. Atkins, There Are Similarities Executed Differently

Before embarking on a diet journey, one should absolutely consult their doctor to see what is best for them. While both diets are low-carbohydrate, high fat, and high protein, they are structured differently. Keto also emphasizes more fat, while Atkins emphasizes protein for the majority.

Is one diet better than the other?

Comparing keto vs. Atkins diet you find similarities, but they are done differently. Speak to a doctor about which is better, based on your medical history.

Which diet is less restrictive?

The Atkins diet is most restrictive in Phase One, but it allows for carbohydrates as time goes on. Keto, on the other hand, really discourages dieters from consuming carbohydrates or from enjoying cheat days.

Which diet results in more weight loss?

Both diets are effective in promoting short-term weight loss. However, they may impact the body differently depending on a number of factors including medical history, body type, age, and more.

Does Atkins require dieters to buy brand-specific foods?

Although there are Atkins-brand foods such as protein bars and shakes, those adhering to the diet are not required to buy the branded food items. It is much cheaper to prepare your own food at home.

Does keto allow for cheat meals?

Keto doesn’t recommend cheat meals, because enough carbohydrates can throw the body out of ketosis. Atkins, however, allows for one cheat meal per week.

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