Low-carb diets restrict carbohydrate consumption in favor of fat. However, not all low-carb diets are the same. It's possible to choose between a diet that's low-carb and high-protein versus a low-carb diet that is more traditional, like the low-carb, high-fat ketogenic diet.
Low-carb, high-fat and low-carb, high-protein diets have similar benefits. If you intend to follow any of these diets for a while, choose the one that gives you the most flexibility and allows you to consume a varied, healthy diet.
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What Is a Low-Carb Diet?
Most people consume a diet that's primarily made up of carbohydrates. According to the Mayo Clinic, the average diet is typically composed of between 45 and 65 percent of its calories from carbohydrates. This is the equivalent of between 225 and 325 grams of carbohydrates per day for someone following a 2,000-calorie diet.
The rest of your calorie intake may be a bit more varied. According to a February 2019 study published in the journal Nutrients, a person eating a traditional Western diet may consume from 10 to 35 percent of calories from protein, while between 20 and 35 percent of calories may come from fat.
In contrast, a low-carb diet is essentially the opposite of a traditional Western diet. A low-carb diet involves restricting carbohydrate consumption. Instead, fat serves as the primary energy source.
Most low-carb diets simply restrict carbohydrate intake. They focus on net carb consumption rather than general carbohydrate consumption. Net carb consumption subtracts any carbohydrates that come from dietary fiber or sugar alcohols before taking the total number of carbs into account.
A ketogenic diet is a very low-carbohydrate diet that drastically restricts carbohydrate intake with the goal of putting the body in a metabolic state called ketosis. This is a state where fat provides most of the body's fuel.
Low-Carb Diets vs. Ketogenic Diets
A low-carb diet can be fairly flexible. For instance, Atkins 100, one of the versions of the Atkins low-carb diet, allows you to consume 100 net carbs per day.
In contrast, a ketogenic diet is a very low-carb, high-fat diet that severely restricts carbohydrate intake. According to a September 2018 study in the Indian Journal of Medical Research, carbohydrate intake in a ketogenic diet typically makes up just 10 percent of your calories.
However, a December 2018 study in the journal Canadian Family Physician says that carbohydrate intake in the ketogenic diet can range between 20 and 50 grams of carbohydrates per day. It is widely accepted that a carbohydrate intake below 50 grams of carbohydrates per day is necessary to maintain ketosis. Depending on the rationale for consuming this diet, carbohydrate consumption may increase after a certain amount of time following the diet.
The main concern when following a strict low-carb diet like the ketogenic diet is whether you can get enough dietary fiber. Dietary fiber comes from plant-based foods like nuts, seeds, fruits and vegetables.
High-Protein vs. Low-Carb Diet
Protein-rich diets have become increasingly popular. One of the more recent variations is the high-protein, low-carb diet. However, high protein, low-carb diets may vary considerably, just as Atkins 100 isn't comparable to the ketogenic diet.
The study in the Indian Journal of Medical Research reports that some high-protein low-carb diets may restrict your carbohydrate consumption further. Rather than having a 10 percent carbohydrate intake, your carbohydrate intake might be reduced to around 5 percent. Your other macronutrients would increase accordingly, for example, 60 percent carbohydrate and 35 percent protein intake.
However, this isn't true for all low-carb, high-protein diets. Some of these diets promote carbohydrates in moderation. For example, an August 2012 study in the journal Physiology & Behavior defines a high-protein, low-carb diet as a diet that contains 20 percent protein, 25 percent carbohydrates and 55 percent fat.
A November 2014 study in the journal _Nutrition & Metabolism _mentions other popular low-carb, high-protein diets, including:
Atkins diet, which initially asks dieters to consume 6 percent carbs, 59 percent
fat and 35 percent
South Beach diet —
carbs, 33 percent
fat and 39 percent
Zone diet —
carbs, 29 percent
fat and 34 percent
As you can see, the concept of a high-protein, low-carb diet can vary substantially. While the Atkins diet starts off as similar to a ketogenic diet (the macros change as you progress through this diet's phases), the Zone and South Beach diets are essentially low-carb, moderate-fat, high-protein diets.
High-Protein vs. Low-Carb Diet Benefits
Both high-protein and high-fat low-carb diets have a variety of benefits. According to an October 2019 study in Acta Pharmaceutica, these diets can help people manage a number of neurological and metabolic disorders, including epilepsy, Alzheimer's disease and Parkinson's disease.
According to the study in the Indian Journal of Medical Research, the traditional low-carb diet (specifically the ketogenic diet) was created as a way to treat epilepsy. Although it's now known as a way to manage diabetes and improve triglyceride levels, this diet may be best known for promoting weight loss.
High-protein, low-carb diets are newer and less well-studied. However, they can help increase satiety, decrease fat mass, promote weight loss and improve blood pressure, as reported in the studies published in Physiology & Behavior and Nutrition & Metabolism.
It's unclear whether there are more health benefits in a low-carb, high-protein versus a low-carb diet; few studies have directly compared the two. However, in some studies, like the one in the journal Physiology & Behavior, the protein consumption seems more important than the low-carb component.
More research is required in order to conclude that one of these diets is better than the other, particularly since there are no studies discussing the pros and cons of long-term consumption of these diets. Both diets have the potential to be unhealthy if consumed over the long term.
Ultimately, the health benefits of these diets may come down to the specific macronutrient ratio that you choose to consume. More important, the healthier diet will be determined by the specific foods you eat.
Fiber and Low-Carb Diets
According to the Harvard T.H. Chan School of Public Health, most adults need between 20 and 30 grams of dietary fiber each day. Fiber is important because it can help protect you from health problems like cardiovascular issues, gastrointestinal problems, diabetes and certain types of cancers. Yet, according to a February 2017 study in the American Journal of Lifestyle Medicine, the vast majority of adults don't consume enough fiber.
If you're on a low-carb diet, it's likely that you'll struggle to consume the recommended amount of this nutrient. It can be challenging to find plant-based foods that are low in net carbs but still rich in dietary fiber. Most people have to restrict themselves to leafy greens. These are healthy, but you would need to eat a lot of them to get an adequate amount of fiber.
According to the USDA, you'd have to eat about a kilogram of spinach, radishes or alfalfa sprouts each day to consume a reasonable amount of fiber. A kilogram of these is equivalent to 22, 16 and 19 grams of dietary fiber, respectively.
Of course, it's unlikely that you'd eat a kilo of any vegetable every day. Hence, over the long term, it can be better to consume a more liberal low-carb diet. A liberal low-carb diet may not have the same range of benefits as a ketogenic diet, but it will give you access to a wider selection of nutrient-rich, plant-based foods and allow you to consume a much more varied diet.
Read more: 19 High-Fiber Foods — Some May Surprise You!
Fat Consumption and Low-Carb Diets
Like fiber, fat consumption is an issue in low-carb diets. This is because many dieters tend to gravitate toward animal proteins and animal fats when following these diets.
Foods like meat, poultry, cheese and other dairy products are all healthy foods. However, it's essential for these products to be consumed in moderation, especially if you're choosing the high-fat versions.
Animal products like these all contain saturated fat. The American Heart Association says consuming large amounts of saturated fat has the potential to increase your blood cholesterol and risk of cardiovascular diseases.
If you intend to follow a traditional high-fat, low-carb diet or low-carb, high-protein diet, make sure you're consuming healthy foods. This means integrating healthy plant-based fats from nuts, seeds or fruits like avocado into your daily diet. It also means primarily cooking with healthy fats, like avocado oil, sesame oil, olive oil or flaxseed oil, instead of butter, lard or margarine.
Many high-fat, low-carb diets don't allow much flexibility in the number of carbohydrates allowed. This can make it challenging to choose a plant-based protein over an animal protein. However, you can always opt for seafood that's rich in unsaturated fats, like fish and shellfish. Certain fatty fish are particularly healthy because they're rich in polyunsaturated fats like omega-3 fatty acids..
If you're following a flexible high-protein, low-carb diet, you may also be able to integrate more nuts, seeds and legumes into your meals. Many of these plant-based proteins are rich in protein and fat and can be an ideal substitute for animal products. Swapping out dairy cheese for cashew cheese or steak for seitan can help integrate more nutrient-rich plant-based proteins into your diet.
High-Protein vs. Low-Carb Diet Downsides
It's important to recognize the downsides of both the high-protein and high-fat low-carb diets. While these issues might not be a problem in the short term, they can lead to serious problems if you don't take them into consideration when following these diets over the long term.
Reduced fiber consumption can obviously be detrimental to your health if you were to consume such a diet over the long term, increasing your risk of developing conditions like cancer or diabetes. However, a November 2017 study in the journal Cell reported that insufficient dietary fiber consumption can affect the health of your gut microbiome. This, in turn, has the potential to make you more susceptible to pathogen-borne diseases.
Similarly, all low-carb diets have the potential to cause health problems if you consume a diet rich in unhealthy fats. Excessive saturated fat consumption has been associated with weight gain and the development of cardiovascular issues, among other health problems. Fortunately, as discussed in an April 2017 publication in the journal Annals of Nutrition & Metabolism, replacing unhealthy saturated fat with healthy unsaturated fat can resolve this nutritional issue.
The study in Acta Pharmaceutica reports that low-carb diets have the potential to cause acidosis and other health issues when consumed over the long term. An April 2018 study in Nutrients reports that this issue is primarily caused by animal-derived proteins. However, counteracting the issue is easy — simply consume a larger amount of fruits and vegetables.
Ultimately, most of the potential issues related to low-carb diets come down to your specific dietary choices and the macronutrient ratio you've decided to adhere to. Swapping unhealthy fats for healthy fats like omega fatty acids and animal fats for plant-based proteins can be easy if your diet is fairly flexible.
- Mayo Clinic: "Carbohydrates: How Carbs Fit Into a Healthy Diet"
- Nutrients: "Utilizing Dietary Nutrient Ratios in Nutritional Research: Expanding the Concept of Nutrient Ratios to Macronutrients"
- Indian Journal of Medical Research: "Ketogenic Diets: Boon or Bane?"
- Harvard T.H. Chan School of Public Health: "Fiber"
- American Journal of Lifestyle Medicine: "Closing America’s Fiber Intake Gap"
- USDA: "Nutrition Comparison of Radishes vs Alfalfa Sprouts Raw vs Spinach"
- Physiology & Behavior: "Relatively High-Protein or ‘Low-Carb’ Energy-Restricted Diets for Body Weight Loss and Body Weight Maintenance?"
- Nutrition & Metabolism: "A High-Protein Diet for Reducing Body Fat: Mechanisms and Possible Caveats"
- Acta Pharmaceutica: "Nutrition – Facts and Myths"
- American Heart Association: "Saturated Fat"
- Annals of Nutrition & Metabolism: "Saturated Fat Consumption and Risk of Coronary Heart Disease and Ischemic Stroke: A Science Update"
- Canadian Family Physician: "Ketogenic Diet for Weight Loss"
- Cell: "A Dietary Fiber-Deprived Gut Microbiota Degrades the Colonic Mucus Barrier and Enhances Pathogen Susceptibility"
- Nutrients: "Dietary Treatment of Metabolic Acidosis in Chronic Kidney Disease"