Low Carb Diets: Keto Vs. South Beach Vs. Atkins

Aug 10, 2021

A hand holding a wrap sandwich

Let’s face it. Carbohydrates have become taboo.

Cauliflower “rice” is so popular that you can buy it pre-made and wrapped in a pretty package in most major grocery stores.

Don’t even get us started on “zoodles” (AKA zucchini noodles). They are delish, by the way, but certainly not the same as the “real thing.”

What about replacing home fries and hash browns with an extra side of bacon? Now we are talking!

That doesn’t sound too terrible, does it? Low-carb diets are trending hard. Every tabloid, fitness journal, yoga magazine, and recipe publication is plastered with “keto recipes,” or “Atkins diet tips,” or “lose it all with the South Beach diet” on the cover.

But what gives? What is the difference between these three low carbohydrate diets, and how should anyone know how to choose the right one?

In this article, we will unpack the nuances, benefits, and shortcomings of each. We will also explain how to follow each of the three, just in case you are ready to cut the carbs and change your life!

Keto vs. Atkins or Keto vs. South Beach: What’s in It For You?

Low-carb diets are all the rage. They have become extremely mainstream in the last five years. The biggest challenge may be deciding which one is the right low-carb diet plan for you.

Is the drastic keto diet versus the phased Atkins diet what you need to shed the final few pounds?

Or are you weary of the extreme measures required for keto versus the more holistic lifestyle change prescribed in the South Beach diet?

If you have questions, we have answers. Let’s unpack the pros and cons of each and how to follow them so you can cut carbs and shed pounds.

If you are wondering which low-carb diet is right for you, read on!


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Of the three low-carb diet plans, keto is easily the strictest. You are either on the keto diet or off of it.

No cheating is allowed because it will kick you right on out of ketosis. Getting back in may cost you a round of the keto flu. (Yes, you can literally get flu-like symptoms when your body transitions into being fat-adapted.)

You see, the sole premise of the keto diet is to get into and maintain the metabolic state of ketosis.

When you restrict carbohydrates almost entirely and eat primarily fat, your metabolism will switch gears from utilizing glucose for energy to using fat instead.

You will produce ketones which will be used as fuel.

With the keto diet, you have to be very strict and very mindful of your macros. (Macros are your dietary building blocks, and everything you eat falls into one of the three macro categories.)

With this low-carb diet, you will be aiming to eat 75% fat, 20% protein, and a mere 5% carbohydrates. Basically, your total carb “budget” will be spent on non-starchy vegetables.

Even most fruit has too much natural sugar to be consumed within the keto confines. You will be loading up on fats. (Hopefully, you have access to healthy fats, and most of your calories don’t come from bacon and cheese.)

Because our hunter-gatherer ancestors had to find a way to get enough glucose to fuel their brains in the wild, our bodies have evolved to convert excess amounts of protein into carbohydrates (in the form of glucose).

Therefore, with the keto diet, you need to pay attention to your tracking. Not only can you blow it by eating too many carbs, but you can also kick yourself out of ketosis by overeating protein.

Your daily carb intake will land right around 20 to 30 grams per day, depending on your BMI. That’s not very much at all.

To give you an idea, a single, medium-sized carrot has over 4 grams of net carbs. A slice of cheese pizza has about 25 grams of net carbs. You may be thinking, “Great! I can still eat pizza occasionally!”

Not so fast. If you max out your carb allowance with a slice of pizza, that means you can’t have any other carbs all day.

All vegetables have at least a little bit of the naughty “C-word.”

Even some fat sources, like cheese, have some carbs too. Sorry to say it, but you are going to have to cancel anything extra unless you want to make a keto-friendly substitute. (Keto pizza crust is usually made with almond flour and mozzarella.)

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The Atkins Diet was created by Robert Coleman Atkins, an American physician, and cardiologist. The original diet is done in four phases.

The last and final phase is a transition from a diet into a long-term lifestyle. In phase one (known by enthusiasts and partakers as the “induction” phase), your carb intake will be under 25 grams.

The only carbohydrates that you are allowed to consume are those that come from nuts, vegetables, cheese, and seeds.

You will stay in phase one until you are only 15 pounds from your target weight. This is one of the significant differences between keto vs. Atkins.

Phase one of Atkins is essentially how keto is all of the time, indefinitely. With the Atkins diet, you can move on to phase two.

In phase two, your carb intake can be from 25 to 50 grams per day. In this “balancing” phase, you can reintroduce fruit, tomato juice, and yogurt.

When you are just ten pounds away from your target weight, you can transition into phase three of the Atkins diet.

Phase three (AKA the “pre-maintenance phase”) has a carbohydrate allowance of 50 to 80 grams per day. In this phase of the low-carb diet plan, you can add in starchy veggies (like potatoes, carrots, and legumes) as well as whole grains.

This is a preparatory phase for the final stage of the diet, which is really just a long-term (indefinite) lifestyle.

Phase four (known as the “lifetime maintenance” phase) allows you to consume 80 to 100 grams of carbohydrates per day. This is expected to be a permanent low-carb lifestyle that you rarely, if ever, stray from.

One of the biggest differences between keto vs. Atkins is that there is a very big emphasis on consuming mostly fats with the keto diet.

The Atkins diet does not prescribe that. It is merely a low-carb diet plan. Keto is also a lot stricter.

Phase one of Atkins is the entirety of keto (without requiring the high intake of fat macros.) While you will likely lose more weight faster on the keto diet, the Atkins diet may be more sustainable for the long term.


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The South Beach diet is another low-carb diet plan, but it was actually designed by an American cardiologist named Dr. Arthur Agatston, who aimed to help patients with heart problems. Similar to the Atkins diet, the South Beach diet is also executed in phases.

In phase one, participants must restrict all fruit juice, starches, alcohols, and added sugars. This phase lasts for two weeks. If these items are part of your regular diet, you will probably lose a substantial amount of weight from this phase.

The next phase allows participants to consume some select carbohydrates, such as whole grains and fruit.

While the weight loss will not likely be as rapid as it was in phase one, it will still happen steadily. When you reach your target weight, you can move on to the third and final phase.

Like the Atkins diet, the last phase of the South Beach diet is all about maintaining the weight loss you have achieved.

At this point, you aren’t necessarily restricting anything in your diet, but holistically trying to make mindful dietary choices. You need to maintain ample exercise. If you should put any of the weight back on, you will need to revisit phase one and start the process again.

When comparing keto vs. the South Beach diet, it is easy to see that keto has a lot more rules.

Phase one of the South Beach diet is somewhat like both the keto diet and phase one of the Atkins diet.

From there, the two don’t have a whole lot in common other than being low carbohydrate diets and having a goal of weight loss and better health.

If you are someone who eats a lot of junk food and you are looking for a phased approach to a lifestyle change, the Atkins or South Beach diets may be enough for you.

If you are already nearing your ideal weight and fitness level, but are struggling to shed the final few pounds, you may need something more drastic, like the keto diet.

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