Can you survive without any carbs in your diet? An army of zero-carb-diet social media influencers seem to think so. 

But what do the actual health experts, like a registered dietitian, have to say about keto, carnivore, and other extremely low-carb diets?

“Carbs are absolutely necessary to feel your best and achieve good health,” says Daisy Mercer, a registered dietitian with MyFitnessPal. 

You may be able to technically survive on a very low-carb diet, but it’s not the kind of healthy, balanced diet that Mercer recommends. 

“We need carbs to think our best and for many other bodily functions to work optimally,” Mercer. 

People are drawn to these very low carb diets because they can produce quick results. Very low carb diets may lead to greater short-term weight loss than low-fat diets. 

But does that mean you should drop that sweet potato and snack on a pork chop instead? Here’s what you need to know about low-carb diets and your health.

Are Dietary Carbs Absolutely Necessary?

To answer this fully, there’s nuance to understand here. 

Our bodies can actually produce carbohydrates in the form of glucose through a process called gluconeogenesis. If you aren’t eating any dietary sources of glucose, the body uses other compounds to make glucose. 

But remember, carbs are the main energy source of the human diet. So while you can technically live without them, you may not feel your best.

Not all carbs are created equal, though. “It is important to choose appropriate carbs that won’t digest too quickly—complex carbs—so we can have a sustained release of energy,” says Mercer. She suggests eating a diet that contains a range of complex carbohydrates, plenty of lean protein, and healthy fat is ideal. 

Complex carbs contain more fiber than simple carbs, which are essentially just sugars. The latter are digested quickly, leading to blood glucose shifts that can leave you feeling tired. 

Thanks to their fiber, complex carbs take longer to break down, giving you sustained energy and keeping you feeling full longer.

What Are Carbohydrates Food Sources?

Instead of demonizing an entire food group, it’s best to understand how carbs work so that you can learn to get the nutritional benefits of carbohydrates while avoid possible pitfalls. After all, many healthy foods are carbohydrates. 

These include:

• Whole grains: Rich in fiber, vitamins, minerals, and other nutrients, whole grains have plenty of health benefits. Whole grains include brown rice, quinoa, oats, whole-wheat bread, barley, and rye.
• Fruits and vegetables: These carb powerhouses are great sources of vitamins and minerals. They also come with a good dose of fiber. Apples, oranges, berries, sweet potatoes, peas, and corn are just a few fruits and vegetables that offer powerful health benefits.
• Legumes: Beans, lentils, and peas are good sources of complex carbs that are also packed with protein and fiber to keep you feeling full longer.

There is a type of carbohydrates you may want to limit: simple or refined carbs. These include foods made with refined sugars and flours. Think: white bread, packaged snacks, cookies, cakes, and other sweets. 

Can the Brain Function Well on a Diet With Little or No Dietary Carbs?

The effect of carbohydrate deprivation on the brain isn’t well understood, but research is ongoing. 

One short-term study compared people on a more balanced diet with people on a low-carb diet. 

Participants were given a range of cognitive tests. The low-carb group performed worse on memory tasks, but they also reported experiencing enhanced attention and less confusion. 

Another small study of older adults with cognitive problems found that a high-fat, low-carbohydrate diet may modestly improve brain function and memory.

More research is needed to learn exactly how the elimination of carbohydrates affects the brain. 

What Is Keto-Adaptation and What Are the Benefits?

The keto diet is named for ketones, which can be used by the body as an alternative fuel source when glucose isn’t around. When carbohydrate intake is very low (typically between 20g and 50g per day), the liver produces ketones from fatty acids. It’s called ketogenesis.

When on a no-carb or very-low-carb diet, your body will eventually enter a state known as ketosis. In this metabolic state, your body functions by burning fat for fuel instead of carbohydrates. 

Keto-adaptation, an element of fat adaptation, is your body’s way of adjusting to using ketone bodies as its main source of energy instead of carbs. 

Research suggests that people on a keto diet may lose more weight than people on low-fat diets.

But a diet with little or no dietary carbs is very difficult to sustain for most people. There’s no evidence that it’s safe to remain in a state of ketosis over the long term. “Your body wants to consume carbs and it isn’t always sustainable for you to limit carb intake,” says Mercer.

In general, it’s important to listen to your body — if the keto diet makes you feel fatigued, dizzy, or irritable, try adding some healthy carbs back into your diet.

Fun fact: There are 2,000 recipes available for free on the MyFitnessPal app. Get inspiration and start tracking your meals today!

What Are the Potential Risks Associated With a Zero-Carb Diet?

Mercer says that in the short term, you might experience brain fog and sluggishness when attempting a zero-carb diet. Constipation and other digestive discomfort can also be a problem. 

Over the longer term, a zero-carb diet may pose other risks to your health. Low-carb diets, like the keto diet, may be associated with as much as a two-fold heightened risk of  “cardiovascular events” like chest pain, blocked arteries, heart attack, and stroke. 

These diets are also linked to:

• Nutrient deficiency
• Kidney and liver problems
• Mood swings

Counting macronutrients (macros) has become a popular way for people to find a better balance of carbohydrates, proteins, and fats. Tracking your macros can help you achieve your health and weight loss goals.

What Is the Best Diet To Lose Weight?

There isn’t a one-size-fits-all diet. The best approach is to ask a dietitian who can create a tailored plan for you. Everyone will experience different results based on their individual metabolism, lifestyle, and health conditions. Remember, consult with your physician before starting any new diet regime to ensure it is right for you.

The Bottom Line

The human body is impressively resilient. Surviving without carbs is technically possible, but it’s not necessary to lose weight. 

A more sustainable lifestyle involves cultivating a healthy relationship with food — that includes enjoying all foods in moderation. 

You can track your carbohydrates daily intake using a food-tracking app like MyFitnessPal. You can easily count your macros and enjoy the right amounts of carbs a day to keep you feeling good.

Originally published May 20, 2016; Updated August 1, 2024