Top 7 Keto Myths: What the Science Really Says

Top 7 Keto Myths: What the Science Really Says

#1 Low Carb & Keto Diet App Since 2010

Track macros, calories, and access top Keto recipes.

Download on the App Store
Get in on Google Play

Top 7 Keto Myths: What the Science Really Says

Posted 8 months ago

Brian Stanton

Brian Stanton


Your body needs carbs to thrive. Dietary fat makes you fat. You can’t get all your vitamins without eating fruit.

These Keto myths probably sound familiar. They’ve scared many people off low-carb living. 

It’s too bad because low-carb diets are a safe and healthy eating pattern. The Ketogenic diet in particular has been linked to fat loss, reduced cravings, and many other benefits beyond weight loss[*][*][*]. 

But Keto has been unfairly cast as the villain in a health drama, where misinformation runs rampant like a stampede of confused buffalo. This article is here to tame those buffalo and clear the confusion so you can make better decisions about your health. 

Keto Myth #1: Carbs Are Essential

Fat, protein, and carbohydrates. Every calorie you consume (not including alcohol) comes from one of these macronutrients. (Fun fact: alcohol is also a macro, but has no nutritional value beyond the calories it provides.)

Only two macros, however, are technically essential for your health.  

Fat is essential. You need fat to absorb fat-soluble vitamins, build cell membranes, and produce energy. 

Protein is also essential. Without dietary protein, you couldn’t maintain muscle, produce neurotransmitters, or heal wounds. 

That leaves carbs. Low-carb critics claim you must eat carbs to maintain normal blood sugar levels. But while blood sugar must stay above a certain point to sustain life, dietary carbs are not a required input. 

Why? Because when you restrict carbs, your body makes its own via gluconeogenesis.[*] You also have about 500 grams of carbs stored as glycogen in muscle and liver tissue. That’s plenty of carbohydrates for blood sugar regulation. 

So when people say they would “die” without carbs, they’re being dramatic. Their bodies would do just fine. 

Keto Myth #2: Eating fat makes you fat

It seems logical that dietary fat when ingested, would end up as body fat. But that’s not how fat-storage works. 

The hormone insulin mediates fat storage. More insulin, more fat storage. High levels of insulin are why people with type 2 diabetes store fat uncontrollably. 

What stimulates insulin release more than any other macronutrient? Right. Dietary carbohydrates.[*

When you eat a high-carb meal, your blood sugar spikes, and insulin arrives to store that excess sugar as glycogen or fat. This fat-storage safety mechanism helps prevent dangerously high blood sugar levels or hyperglycemia. 

Eating fat, on the other, has a minuscule effect on insulin levels.[*] When insulin stays low, it’s easier to burn body fat. 

Keto Myth #3: Dietary fat causes heart disease

In the 1950s, a doctor named Ancel Keys presented global population data linking saturated fat consumption to heart disease.[*] Though his research was deeply flawed, his findings have thoroughly penetrated the public consciousness. Even today, many people still think that eating fat clogs your arteries. 

But this myth hasn’t withstood the test of time. Two recent meta-analyses—massive reviews that followed nearly 1,000,000 people—found zero link between eating saturated fat and heart disease risk.[*][*] And in nearly 60,000 Japanese men, higher saturated fat consumption was linked to lower stroke rates.[*]

You should still track your cholesterol on Keto. (Some folks fare best on a lower sat-fat Mediterranean Keto diet.) But understand that most fat-causes-CVD claims are relics from another era. 

Keto Myth #4: You’ll develop nutrient deficiencies on Keto

On a low-carb Ketogenic diet, you restrict all sources of carbs, including fruit and whole grains. Because of this, some people worry about nutrient deficiencies.  

Truth moment. A well-formulated low-carb diet is more, not less, nutrient-dense than a diet with unlimited fruits and grains. Meat, healthy fats, and non-starchy vegetables like kale and spinach are much better sources of micronutrients than most fruits and grains. 

Meat and low-carb veggies bring you more magnesium and potassium than most carb-containing foods. For example, one cup of spinach contains twice as much potassium as a banana. 

Whole grains also contain anti-nutrients (like phytic acid) that decrease mineral absorption.[*] You won’t have this issue on Keto. 

Keto Myth #5: You need carbs to fuel exercise

Dogma holds that you must “carb up” before, during, and after exercise for optimal performance. Yet, despite being widely accepted by the athletic community, this hypothesis has been invalidated for over 40 years.

In 1980, Dr. Stephen Phinney showed that obese people lasted longer on the treadmill (and burned more fat) after six weeks on a ketogenic diet.[*] In 1983, he showed that cyclists could still perform at the highest levels without carbs.[*

The bottom line? After a short adaptation period, fat fuels exercise just fine. 

Keto Myth #6: You need carbs to build muscle 

Visit any bodybuilding forum, and you’ll find strategies for maximizing insulin, a growth-promoting hormone. The more carbs you eat, the more insulin rises, the more muscle you can gain.

But while massive insulin secretion can help with gains, you don’t need much to build or maintain muscle.[*] Instead, you need:

  1. Sufficient protein (specifically, the amino acid leucine)
  2. Resistance training 
  3. A t-shirt that says “Gym Hair Don’t Care” (optional)

Let’s review the evidence. In one study, young men had increased muscle synthesis on a low-carb, moderate protein diet compared to a higher-carb Western diet.[*

Keto Myth #7: Low-carb isn’t safe long-term

There isn’t much long-term data on low-carb dieting. Tracking human health over several decades is difficult and expensive, and drug executives aren’t lining up to fund nutrition research. 

Still, there are clues. The traditional Inuit, for instance, ate a super low-carb diet of mostly whale and seal. Their diet kept them healthy before Western foods infiltrated their culture.[*

There’s medium-term data too. For example, the two-year Virta Health study (a supervised Keto diet for people with type 2 diabetes) found improvements in body weight, blood pressure, triglycerides, blood sugar, and inflammation.[*] When these markers improve, we can assume these folks are getting healthier. 

Next Steps on Your Low-Carb Journey

Now that we’ve lanced the most common Keto myths, it’s time to apply this knowledge to the laboratory of your life. If you haven’t tinkered with a low-carb diet yet, perhaps it’s time to start. 

Try Keto for a few weeks, then ask some questions. Am I feeling better? Am I losing weight? How does my bloodwork look? How’s my energy during exercise?

Use your answers to guide your future actions. Keep the facts in view and steer clear of the misinformation stampede. That’s how you level up your health.