The ketogenic diet gained popularity through the weight loss community. It’s a low-carb (often 25g per day), high-fat diet triggering the body to burn fat for energy instead of carbohydrates.

With increased popularity, there has also been an increase in keto-naysayers; they think it’s a dangerous fad fueled by the common desire to lose weight.

“It’s unhealthy and unsustainable,” they say. “How can a high-fat diet help you lose weight? It’s dangerous for the heart, increases the risk of ketoacidosis, leads to poor mineral intake and electrolyte imbalance,” they say. But the ketogenic diet has a well-established history of aiding in disease treatment. It has been used to help people with epilepsy (especially children) since the early 1900’s, and more recently, it has been used to manage type-2 diabetes (since it lowers the need for insulin therapy).

With all the noise surrounding the ketogenic diet, it’s difficult to know what to believe. So we’re here to set the record straight, and provide information to help make well-informed decisions about the keto diet. Below, we’ve gathered some common misconceptions about the ketogenic diet and provided answers to help cut through all that static.

“If I eat so much fat, won’t I get heart disease?”

The short answer is “no.” It’s important to note there are several different groups of fats, including trans, saturated and unsaturated.

Not all fats are created equal in the realm of disease risk.

Old school dietary conventions suggest eating fatty foods increases the risk of heart disease and lead to high cholesterol levels.

The keto diet requires ample fat to provide energy and compensate for the reduction in energy from carbohydrates. Foods that are rich in fat include meats, cheese, oils, fish, butter, cream and eggs.

Saturated Fats

These are commonly found in animal products and oils (coconut oil, palm oil, palm kernel oil, olive oil). For years, saturated fat was believed to be a key cause of heart disease. That opinion was largely based on the results of epidemiological studies, and the methodological flaws and potential biases of these studies have since come to light.²

A recent, more comprehensive study found that people who ate more saturated fat had an overall lower mortality rate and no increase in death from heart disease.³

So, getting energy from saturated fat while following a ketogenic diet doesn’t appear to be the health risk it was pegged as.

Unsaturated Fats

Avocados are the poster child of “good fats.” This type of fat, often found in plant-based foods, can be separated into polyunsaturated fats (found in fish and walnuts) and monounsaturated fats (found in avocados, flaxseed oils, nuts and seeds). There’s evidence that replacing saturated fats with “good” unsaturated fats can lower the risk of heart disease and help prevent insulin resistance.⁴

A recent study illustrated that switching from a carb-rich diet to a diet higher in unsaturated fats reduced cardiovascular risk, lowered blood pressure, and improved cholesterol and lipid levels.⁵

Trans Fats

These are harmful fats, found mostly in vegetable oils when they’re partially hydrogenated through heating. They’re also found in processed snacks, baked goods and margarine–foods to avoid on the ketogenic diet.

Interestingly, partially hydrogenated oils (PHO), which are the primary dietary source of artificial trans fat in processed foods, aren’t GRAS (generally recognized as safe) by the FDA.

Cholesterol

Produced by the liver, cholesterol is also derived from our diet. People often assume eating foods rich in cholesterol will raise cholesterol levels and increase the likelihood of a heart attack. But it’s more complicated than that. Cholesterol-rich foods feature heavily in the keto diet (butter, eggs, red meat); but there are two types of cholesterol. “Bad” LDL cholesterol (think L = lethal) is linked to clogging of the arteries. “Good” HDL cholesterol (think H = healthy) clears cholesterol from the blood.

Research shows there is a weak relationship between levels of dietary cholesterol and blood cholesterol.⁶ The effect isn’t the same for everyone either. There are “responders” and “non-responders” to dietary cholesterol; some people experience higher fluctuations in blood cholesterol levels according to the amount of cholesterol they eat, while others are more stable regardless of diet.

Regarding the keto diet, experts recommend focusing not on total cholesterol levels of the food, but instead on the impact food has on LDL and HDL ratios. Consuming plenty of polyunsaturated fats increases blood HDL levels while reducing LDL. Since saturated fats and trans fats increase LDL levels, these should be reduced.

Still, it’s important to keep track of blood biomarkers when starting out on a ketogenic diet to help ensure the diet isn’t increasing risk factors for heart disease.

“You’ll get fat eating all that fat!”

It may seem counterintuitive: how can a diet high in fat not lead to weight gain?

Often the biggest misconception about the keto diet: eating fat leads to weight gain or obesity.

That’s likely because we’ve been conditioned to believe eating a low-fat diet leads to weight loss. But all dietary fat doesn’t end up as belly fat.

Metabolism

When we eat proteins and carbohydrates, the pancreas releases insulin into the blood. Insulin is a hormone that signals to our cells to absorb nutrients (such as glucose) and to start using glucose for energy. Any excess glucose is stored as glycogen or converted into fat by the liver or specialized fat storage cells.

Insulin isn’t released when fat is consumed. Fat is absorbed in the intestines and enters the bloodstream circulation as lipoproteins. Fat is a major source of energy for the body, so much of the fat consumed in food is used to keep us alive.

Excess fat is broken down and stored as fatty acids in the liver, or as body fat. This shows that even though proteins, fats, and carbohydrates may be metabolized differently, in both mechanisms the excess food energy is stored as body fat.

Dietary Fat Doesn’t Immediately End Up as Body Fat

Instead, it should be recognized that in excess food in general–whether carbohydrates, proteins or fat–can become body fat.

Low-calorie, low-carbohydrate diets are increasingly recognized to be more satiating than low-calorie mixed diets (meaning, overall calorie intake is reduced to promote weight loss).⁷Many people on the keto diet commonly experience the feeling of being more satisfied after eating, and this could contribute to weight loss–but scientists have yet to find a clear advantage of keto for weight loss when compared to any other calorie-controlled diet.

“Doesn’t the keto diet cause dangerous shifts in electrolytes and water levels?”

Drinking enough water, especially in the first few days of the diet, is imperative to help the body’s water levels reach a new steady level.

A keto diet causes a substantial shift in body water and electrolyte levels in the first few weeks. Decreasing the amount of carbs consumed means glycogen stores in the liver are depleted. Water is store alongside glycogen (for every gram of stored glycogen, three grams of water are stored).

As glycogen stores are depleted, the body loses water.

Experiencing Keto Sickness or (Keto Flu)

As excess water is expelled in urine, it takes with it important minerals the body needs to function properly.

Electrolyte imbalance can cause a range of side effects, including muscle cramps, constipation, brain fog, and low energy. This contributes to the “keto flu,” a phenomenon people commonly experience as the body adapts to the new, low-carbohydrate diet. You can read about the keto flu and how to mitigate its symptoms, here.

It isn’t healthy to have long-term electrolyte imbalance–but it’s easy to prevent, through adequate supplementation of electrolytes and consumption of nutrient-rich whole foods. Eating things like salmon, nuts, avocados, broccoli, and leafy greens can ensure an adequate intake of magnesium, sodium, calcium, and potassium.

Dehydration and electrolyte imbalance are inconvenient and uncomfortable, but they can be easily rectified and are unlikely a danger to health.

“The keto diet is dangerous for athletes and people doing exercise.”

Athletes on a ketogenic diet become more efficient at using fat as fuel during exercise (through beta-oxidation). But it does require some training to tap into the huge amount of energy stored as fat.

Diet and Exercise

Usually, when exercising at a higher intensity, the amount of fat burned goes down, and the amount of carbs burned goes up.⁸ Athletes will always use some carbs to fuel moderate/high-intensity exercise. For athletes eating a mixed diet, peak fat burning occurs at about 55% of max intensity.

But a study of keto-adapted athletes found that these individuals reached peak fat burning at 70% of max intensity.⁹ These athletes needed to burn far fewer carbs than athletes eating a traditional diet.

In theory, this means keto-adapted athletes can tap into a huge amount of energy stored as fat, needed to assume less fuel during training and racing to have greater endurance.

There isn’t any clear evidence yet of a boost in endurance performance for athletes in ketosis through diet. Exogenous ketones like HVMN Ketone have been shown to increase endurance, presumably because the body can take advantage of burning ketone bodies, carbs and fats.¹⁰

Carbs as Fuel

Carbs are still the primary fuel for the body during high-intensity exercise. A ketogenic diet may be better suited to athletes performing endurance sports (like marathon running or cycling). Athletes engaged in more intense cardio (like sprinting, hockey, football) may perform better with a higher percentage of carbohydrates. These athletes may experience a decrease in high-intensity output while following a ketogenic diet, but ultimately, a lowered carbohydrate intake as isn’t “dangerous” for athletes.

Muscle Catabolism

“Catabolism” means the break down of muscle tissue. A common misconception is that athletes switching to a keto diet could trigger muscle catabolism.

There’s no evidence suggesting athletes experience muscle catabolism when eating enough calories on the keto diet. In a meta-analysis, looking at low-carb diets, it was found the diet resulted in greater weight loss and muscle maintenance than diets higher in carbs.¹¹

More long-term studies are required, but from existing literature, it seems the keto diet may even be protective against muscle protein catabolism as long as the diet contains a sufficient amount of protein.¹² For those wanting big gains in muscle size or strength, the ketogenic diet isn’t the best option to help achieve that goal.

“Keto diets aren’t ‘complete’ and lead to nutrient deficiency.”

Balance is important in any diet, and a proper keto diet should incorporate nutrient-rich foods.

Losing essential micronutrients is another concern raised by keto diet skeptics. People say eating a diet based on fat and protein from animal sources means losing those micronutrients found in higher-carb grains, legumes, fruits, and vegetables. Some also claim low-carb diets contain too little fiber, and thus may cause long-term constipation. That’s inaccurate.

Nutrient-Rich and Keto-Approved

There are many options for nutrient-rich, low-carb foods, and they should be frequently incorporated into the keto diet.

Examples include non-starchy fruits and vegetables such as leafy greens, mushrooms, bell peppers, and berries. The trace minerals and vitamins found in grains can also be obtained at higher percentages in good-quality meats and dairy products. Moreover, compounds such as phytates and tannins in grains hinder the bioavailability of several minerals.¹³

A properly constructed keto diet may even be higher in nutrients than a standard American diet, especially when things like candy, refined flour, soda, and processed carbs are eradicated.

A well-formulated keto diet should feature plenty of whole, unprocessed foods and shouldn’t lead to nutritional deficiencies.

“Doesn’t the keto diet cause dangerous ketoacidosis?”

These are two very different terms, but ketosis and ketoacidosis are often confused. The keto diet doesn’t cause ketoacidosis.

Ketosis

Ketosis indicates the presence of ketones in the blood at > 0.5 mM. Achieving ketosis can happen through diet or fasting, and also rapidly through ketone supplements like HVMN Ketone.

When people reach ketosis through fasting, ketone levels naturally plateaued at ~8 mM after 41 days of starvation.¹⁴ This is far lower than ketone levels during ketoacidosis. A ketogenic diet should only result in ketone levels that fall within a natural and safe range.

Ketoacidosis

This is a condition typically seen in type-1 diabetics, where ketones and blood sugar levels are both dangerously high (ketone levels at 20+ mM). The key factor in the development of ketoacidosis is a lack of insulin. The cells cannot shuttle in glucose from the bloodstream for energy use and the body has no signal to stop releasing fats (which are converted into ketones).¹⁵ Those who have even a small amount of insulin secretion or signaling do not often reach this metabolic state.

When ketone levels get too high, the blood becomes too acidic, which could potentially become life-threatening. Other medical problems linked to ketoacidosis include alcoholism, overactive thyroid, and infections such as pneumonia or drug abuse.

Ketoacidosis isn’t a danger directly associated with the ketogenic diet.

“Could the keto diet cause hormonal imbalance?”

Hormonal response between individuals on the keto diet varies widely (including between men and women). A careful keto dieter should be able to maintain healthy hormonal balance.

Hormonal imbalance is a hot-button topic when it comes to the keto diet. There’s a discrepancy in the scientific results, which may stem from differences in the exact dietary protocols used, and the cohorts studied.

Cortisol

This is one of the first hormones most people think will suffer via the ketogenic diet. Cortisol is called the “stress hormone” in the body due to its role in stress response, and several other functions like breaking down fat and protein to make glucose. It also controls sleep and wakefulness as well as regulation of blood pressure.

Chronically, high cortisol levels are detrimental to health and may increase the risk of heart disease. Are these levels possible to attain while on the keto diet? Only if you aren’t careful.

A lack of sodium on the ketogenic diet can cause the brain to send signals to the adrenal gland to increase the release of hormones responsible for water balance. Cortisol is released alongside these other hormones.

If sodium consumption is enough to maintain a normal water balance, then cortisol levels should stay stable. Few studies have measured cortisol levels of people on keto and the results are inconclusive. One study found that cortisol increased over time in subjects given a ketogenic diet with a low/inadequate sodium intake.¹⁶

Another study showed no change in cortisol after six weeks of a well-formulated ketogenic diet.¹⁷ Cortisol is infrequently measured, which may be an indication that generally, doctors and scientists have few concerns about cortisol on a ketogenic diet.

Thyroid Function

A supposed danger of the keto diet is a negative impact on thyroid function.

The thyroid hormones have several functions, including control of the body’s metabolic rate, digestion, and muscle control, among others. The ketogenic diet is linked with a decline in the amount of active thyroid (T3)¹⁸ in the body, which is why it’s assumed the diet impairs thyroid functioning.

However, this is not backed by any solid studies. The body’s sensitivity to T3 has been hypothesized to increase as a result of the ketogenic diet, in a similar way increased sensitivity to other hormones occurs during the diet. As the body becomes more responsive T3, it may function just as well or even better than before with lower T3.

Studies point to the beneficial effects of lowered T3 to assist in sparing lean muscle.¹⁹Lowered T3 is even hypothesized to be an adaptive mechanism increasing longevity.²⁰

Regarding metabolism: one study found when men on either the ketogenic diet or the low-fat diet were compared, their resting metabolic rates were not different despite lowered T3 on the ketogenic diet.²¹ Of the several studies done on the ketogenic diet, none have reported significant cases of hypothyroidism–essentially, the thyroid can function fine while following a ketogenic diet.

“I’ve heard that the keto diet causes kidney stones and gallstones.”

The unfounded association between the ketogenic diet and kidney stones is perhaps due to the supposed link between dietary protein and kidney stones–there’s a common confusion between the ketogenic diet and a high-protein diet.

Can Keto Cause Kidney Stones?

Kidney stones are mineral deposits in the kidneys. They can be caused by multiple things–including dehydration, high sodium intake, family history, and excessively high consumption of protein (> 200g per day). A true ketogenic diet is low-carb, moderate-protein, and high-fat. So there’s no solid evidence that protein consumption at levels seen in a typical ketogenic diet could cause kidney stones.

Gallbladder Issues

Another common false connection exists between the keto diet and increased risk of gallbladder issues. Why?

The main role of the gallbladder is to store bile (which is made in the liver), and in turn, the role of bile is to digest fat. People assume eating a lot of fat is somehow linked to an increased risk of gallstones, which are solid deposits of cholesterol and bile that can form in the gallbladder. But most of the cholesterol in the bloodstream is made inside the body (as part of a tightly regulated process inside the liver), not derived from the diet.

None of the common causes of gallstones (including inherited body chemistry, body weight, low gallbladder motility, and low-calorie diet) are linked to the keto diet.

Comparing those who lose weight on a low-fat diet versus a low-carb diet, studies show those on the low-fat diet are more at risk of developing gallstones.²² And eating high fat is thought to stimulate gallbladder emptying, which could be even protective against stone formation.

Is the Keto Diet Right For You?

It’s important to survey the information available and sift facts from the myths. Many of those myths are covered in a cloud of confusion surrounding the relevance of the research, inadequate facts and media hype.

Many of the perceived dangers are minor inconveniences which can be overcome by careful diet and lifestyle management. These “dangers” are also issues present in any calorie-restricted diet (including low-fat diets) and are not unique to just the keto diet.

It’s obviously important to keep in touch with a doctor for health-related lifestyle changes. But feel confident embracing a properly-formulated ketogenic diet–rich in whole foods, adequate hydration and electrolyte consumption–to help avoid any of these dangers.