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Internal Medicine

The Most Popular Low-Carb Diets, Compared

Low-carb diets are all the rage. But each new plan emphasizes different foods. Take a closer look at the menu to see if it's a fit for you.


woman stands in front of a fridge filled with vegetablesMost people try out a diet for a short time, break it and then move onto the next big thing. And there are plenty of diet trends to choose from. Keto, Paleo, Whole30, Atkins, South Beach — they may seem like different versions of the same diet, served up in a new name.

But no two low-carb diets are the same. The health benefits and results you see may differ dramatically — assuming you’re able to stick to the plan.

That’s the most important ingredient for long-term success, says Lena Rydberg, DO, an Internal Medicine physician at The Iowa Clinic in West Des Moines. She breaks down the most common low-carbohydrate diets to help you avoid cycling through the latest diet trends and find one you can stick with in the long run.

What is a low-carb diet?

Any diet that limits the amount of carbohydrates you eat is a low-carb diet. And there are many. In the simplest terms, low-carb diets emphasize foods high in fat and protein, while restricting foods filled with carbohydrates.

Many people are attracted to a new diet to lost weight . Those switching to a low-carb diet are often looking for more than just weight loss. Low-carb diets can help you control diabetes on less medication. They help women with hormone-related problems cycle more regularly and reduce acne. But, most importantly, they can help you modify your diet to establish healthy eating habits long-term.

“Other types of diets require you to limit or count calories. This can make you feel restricted. If you’ve followed a calorie-restricted diet in the past, limiting carbs alone can feel liberating,” says Dr. Rydberg.

Studies show that a low-carb diet can help you lose weight if you follow one long-term. Since weight is a contributor to obesity, diabetes and a number of other serious conditions, a low-carb diet can also improve your health and reduce your risk of disease.

What’s the best low-carb diet?

“It depends on which one makes you feel the best. That’s the diet that’s going to work better for you,” says Dr. Rydberg.

Restricting yourself from foods you enjoy and forcing yourself to eat things you can hardly stomach ensure you’ll eventually break your diet. The same applies to your feeling of fullness. If your diet isn’t keeping you full, you’re more likely to eat whatever’s convenient and overindulge in those moments of hunger.

“When you’re hungry, it usually means that something you ate previously wasn’t working very well. A lot of times, it’s the time of day,” says Dr. Rydberg. “You might need to increase the fat or fiber prior to that time where you typically feel hungry. So you’re able to pass up those cookies in the breakroom and have an easier time saying, ‘I don’t need that. I wouldn’t even enjoy that cookie very much.’”

Simple carbohydrates, the ones found in breads, pastas and baked goods don’t keep you full for very long. Complex carbs in fruits, vegetables, nuts, beans and dairy can. These foods are either high in fat or high in fiber — two things that raise your blood glucose more slowly to make you feel fuller longer.

The various low-carb diets treat carbohydrates differently. You could be cutting out a staple of a healthy diet that helps tide you over until the next meal. You have to understand what you’re eating, what you’re removing and how that will affect your body before you start one of these common low-carb diets.

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Keto Diet

The Ketogenic diet, or “Keto,” is one of the newest and most popular low-carb diets. So much so that phrases like “Keto-friendly” are starting to pop up on product packaging.

The goal of Keto is to achieve “ketosis” — the point where your body burns fat instead of sugar to fuel itself. Many diets can get you to that point for a short period of time. Followers of Keto try to maintain that for weeks or months at a time. To get there, the Keto diet emphasizes:

  • Lower carbs – Carbs are almost banned entirely. Only low-carb fruits and veggies are allowed, including berries, avocado, broccoli, cauliflower, green beans, bell peppers, zucchini and spinach.
  • Moderate protein – Lean protein is a staple of the Keto diet. Chicken, turkey, fish, seafood and lean cuts of beef are allowed. Eggs, nuts, seeds and oils are other good protein sources.
  • Higher fat – Keto focuses on good fats found in the foods above. It also allows dairy, so cheese, plain yogurt, cream and butter are okay.

“It’s a high fat diet. If you’re having trouble feeling full, a lot of times, you’ll feel better on a Keto diet because of that fat content,” Dr. Rydberg says. “Not all fats though are created equal. Just because you can have butter and beef doesn’t mean that should be the main source of your fat.”

She recommends limiting foods, like butter and beef, that are higher in saturated fat. Instead, look for monounsaturated, heart-healthy fats like those found in nuts and oily fish like salmon and tuna.

“Many people feel sharper when they are on the Keto diet long term. In fact, some studies are looking at the prevention or treatment of dementia on this type of diet,” Dr. Rydberg says. “The first few days can be a little rough, though. The body is adjusting to a lower level of carbs which can give you ‘the Keto flu.’ You may feel weak and dizzy or get dehydrated.”

If you have certain medical conditions, you need to talk to your provider before going Keto. For example, it’s not a good diet if you have chronic kidney disease. And if you’re a diabetic and are on insulin, your medications should be adjusted before starting a Keto diet.

Paleo Diet

The Paleo diet gets its name from the Paleolithic era — the Stone Age, basically. The idea behind the Paleo diet is that you should only eat foods that could be hunted or gathered by humans in Paleolithic times. It’s often called the caveman diet for this reason.

“Not everyone is going to do well on a Keto diet,” says Dr. Rydberg. “Paleo is another low-carb, high fat, moderate-protein diet that can help keep you full.”

If you love your fruits and veggies, Paleo might work for you. Both are allowed on the diet. Other foods are banned though, specifically anything that came with the advent of agriculture. Dairy, grains, beans, legumes, sugar and processed foods are a no-no.

Critics argue that there’s nothing magical about how people ate in the past so the rules don’t always make sense. Dr. Rydberg agrees.

“Sure, it makes sense to get rid of sugar and processed foods. That does include grains because they have to be heavily processed to be made into breads,” she says. “But why are we getting rid of legumes? They are packed with fiber and protein.”

Atkins Diet

The oldest of the modern low-carb diet plans, the Atkins diet was originally promoted in the 70s and has maintained its popularity ever since. It takes a different approach than more recent low-carb diet trends. You change your diet in four phases, with each one allowing for more carbohydrates.

The limit on carbs depends on the phase but, in general, the Atkins diet allows higher amounts of carbohydrates and encourages much more protein. You can get protein from meat, butter, eggs and cheese. Bread, pasta, potatoes, cereals, sugary foods and high sugar fruits and vegetables are off limits.

Over the years, the Atkins diet has shown to be effective for weight loss. But it can be harder to maintain than other low-carb diets because it restricts so many types of carbohydrates. It also relies much more heavily on protein, which can be problematic.

“You can overdo it on protein. Too much protein just ends up getting deposited in the kidneys or causing other issues,” says. Dr. Rydberg. “All you really need is an amount that maintains your muscle mass as you’re losing weight, which is what the goal is. And that could be from any meat or non-meat source.”

You only need about 1 to 1.5 grams per kilogram of your weight to maintain your muscle mass. For the average American woman at a normal weight, that’s 75 grams of protein a day. For the average American man, it’s 90 grams. That isn’t as much protein as you might think — especially when protein-fortified foods are everywhere. it’s easy to consume too much when protein is everywhere.

“It’s become popular to add protein powder to everything. I caution people with that because again that’s not a natural food. It is easy to get too much,” says Dr. Rydberg. “If you’re following Atkins, or any other high-protein diet, check with your doctor to determine how many grams of protein you should aim for each day.”

South Beach Diet

The South Beach diet is lower in carbs, but it’s not a strict low-carb diet like Atkins, Paleo or Keto. There’s no carb counting either. You focus on balance instead, eating a mix of good carbohydrates, healthy fats and lean protein. Whole grains, fruits, veggies, lean meats and healthy oils are all allowed.

The South Beach diet uses a phased system similar to the Atkins diet. It also gets more lenient with carbs along the way as you progress from the elimination phase to the long-term weight loss phase to the maintenance phase. The latter two phases are particularly effective in creating heart-healthy habits.

Even with a greater balance of carbs and protein, the South Beach diet is high enough in protein to raise liver and kidney concerns. You may also lack fiber and other nutrients if you’re on it long-term and not keeping an eye on all of your nutritional needs.

Whole30 Diet

Whole30 is different from all the other low-carb diets. It isn’t a long-term diet. And weight loss isn’t a primary goal.

It’s a 30-day elimination diet that’s designed to cut out unhealthy foods and reshape your eating habits. The Whole30 diet is similar to Paleo, yet even more restrictive.

In addition to sugar, grains, legumes, processed foods and dairy, the diet plan bans all sweeteners (natural and artificial), alcohol and baked goods. And unlike Keto or Paleo, there’s no specifics on fat, protein or carbohydrate levels — just a long list of what you can and cannot eat.

The one month trial is very appealing to people wary of committing to a long-term diet. But a permanent improvement of your eating habits should be a goal. So to maintain the benefits achieved while on a Whole30 diet, you have to continue eating well after the month is over. Otherwise, you risk gaining back any weight lost and returning to bad eating habits.

How can I stick to a new diet?

Trial and error can leave you feeling deflated. If you have trouble adjusting to a new diet or aren’t seeing the results you hoped, it can sap your motivation to try something new.

You have to listen to your body and adjust accordingly over time. Because some people respond better to one diet over another, says Dr. Rydberg, who works with patients to improve their diets by establishing healthy eating habits.

“I usually track patients for somewhere between a week and a month. We look at how well they’re able to stick to their diet,” she says. “We try to either increase fat or fiber to see if that curbs hunger and helps them stick to things a little bit better.”

So you don’t have to fully commit to a strict Keto, Paleo, Atkins, South Beach or Whole30 diet. You can take the parts that work for you, adapt the diet to your own body’s needs and work with experts like Dr. Rydberg if needed.

Making these changes takes time. It also takes a lot of dedication and consistency. Once you develop a plan that works for you, you’ll save money on the latest diet advice books and subscription services because you’ll have a diet that outlasts every new diet craze and helps you maintain your health and weight for life.

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