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Ketogenic Diets: Myths vs. Reality


The ketogenic diet is loved by some and hated by others.

Unfortunately, advocates of the ketogenic diet lifestyle magnify the potential benefits, and critics exaggerate the potential shortcomings of the diet. Because of this, many myths and unfounded beliefs exist about the ketogenic diet.

Fortunately, there has been some scientific investigation into many of these myths, so you do not have to be at the mercy of quackery and pseudoscience!


Myth #1: Ketogenic Diets Lead to Ketoacidosis (a life-threatening condition)

Despite the similarity in name, ketosis and ketoacidosis are two different things. The metabolic state of ketosis has been described as clinically benign and should not be confused with the pathological state of ketoacidosis [1]. Ketoacidosis is a life-threatening condition resulting from dangerously high levels of ketones. In ketoacidosis, your body fails to adequately regulate ketone production causing the ketones to skyrocket!

The severe accumulation of ketones causes an unhealthy increase in the acidity of the blood and subsequently changes the normal functioning of internal organs like your liver and kidneys. If you measured your ketone levels while in ketoacidosis, they would register at levels of 15-20 mmol/liter or more.

If you were in this state, you would also have some of these symptoms:

  • Extreme thirst
  • Frequent urination
  • Dehydration
  • Vomiting
  • Stomach pain
  • Nausea

In extreme cases ketoacidosis can be fatal. However, it is important to note that the state of ketoacidosis is almost always associated with uncontrolled type I diabetes—not in individuals that are healthy [2].

Nutritional ketosis, on the other hand, is the result of a nutritional approach that both non-diabetics and diabetics can safely achieve through low-carb nutrition. With this approach, you have a higher than usual level of ketones in your blood or urine, but not high enough to cause ketoacidosis. According to Volek and Phinney in their book “The Art and Science of Low-Carbohydrate Living”, nutritional ketosis is defined by blood ketones ranging from 0.5-3.0 mmol/liter [3].


Myth #2: The Ketogenic Diet is Superior to Other Types of Diets for Fat Loss

This is probably the biggest misconception about ketogenic diets.

Are ketogenic diets effective for weight loss? Yes! Multiple studies have reported the effectiveness of ketogenic diets for fat loss [4-6].

But, low fat diets, low protein diets, and any “diet” that reduces your caloric intake is also effective for weight loss.

The real question is if ketogenic diets are somehow superior to other types of diets, and the answer is ‘no’. This statement is surprising to many keto advocates, and the first thing they would point to is the list of studies that report ketogenic diets outperforming other diet types.  However, nearly every controlled study that matched protein and caloric intake between ketogenic diets and non-ketogenic conditions have failed to show a fat loss advantage for the ketogenic diet [7-9].

What this means is that when both the ketogenic diet and the non-ketogenic diet reduce calories by the same amount AND make sure that protein intake is equal in both dieting conditions—the ketogenic diet is no more effective than the non-ketogenic diet. When dieting, it is the protein aspect of the diet that takes priority. This is the primary reason Avatar Nutrition prescribes relatively higher protein intakes because the science is very consistent in reporting that higher protein is essential for maximizing fat loss and preserving lean body mass [10-12].


Myth #3: Ketogenic Diets Offer No Advantages Over Other Types of Diets

If there is an advantage of ketogenic diets over non-ketogenic diets for fat loss, it is potentially in the realm of appetite suppression [13]. Under non-calorically restricted conditions, ketogenic diets have consistently resulted in body fat and/or body weight reduction [14-15].

This occurs via spontaneous food intake reduction. Nutrition scientists are currently unsure of the reasons why a ketogenic diet may suppress the desire to eat, but it could be due to increased satiety (the feeling of being full) through an elevation of ketone body production and a suppression of ghrelin production [16]. Ghrelin is a hormone, that, when released, causes you to be more hungry. Therefore, the less ghrelin that is present, the less hungry you are!

To demonstrate this, researchers from the United Kingdom instructed subjects in their study to follow a ketogenic diet [15]. But, they did not tell the subjects that they had to decrease their calories while following the ketogenic diet—essentially they could eat as little or as much as they wanted! When the subjects followed the ketogenic diet, the consumed about 200 fewer calories per day than when they followed a non-ketogenic diet.

In addition to its ability to suppress appetite, there are a few other benefits that are unique to ketogenic diets.  In rodent models, it has been demonstrated that ketogenic diets improve inflammation and reduce oxidative stress [17-19]. Also, recent research has reported that ketogenic diets promote brain macroautophagy, which is the brain’s way of cleaning house (getting rid of damaged cell components and debris) [20]. This could be particularly important for those using a ketogenic diet for improvement of neurological disorders, including Parkinson’s disease, multiple sclerosis, etc.


Myth #4: Low Carb Diets Cause Muscle Loss

Many weight-loss diets that reduce body fat also cause a loss of muscle mass [21]. Nutritional interventions that could lead to retention of muscle mass during weight loss would be beneficial for several reasons, including keeping your metabolic rate elevated and performance in the gym at a high level [1].

Is the ketogenic diet that ‘special’ nutritional intervention that could lead to superior retention of muscle mass during weight loss? At first glance, the answer is a resounding NO. The majority of published research reports a decrease in muscle mass when following a ketogenic diet [22-24].

However, nearly all of the scientific research to date has not incorporated resistance training in conjunction with a ketogenic diet. Including resistance exercise when dieting is important as this not only keeps muscle mass from being lost during a diet phase, but also maximizes fat loss [25-26].

There have only been a few reputable studies that have included resistance training during a ketogenic diet.  In one of these studies [27], it was reported that the inclusion of resistance training during a 10-week ketogenic diet resulted in a significant amount of fat loss and, interestingly, no loss of muscle mass!  The other study did report a loss of muscle mass in the ketogenic diet group, but the amount of muscle that was lost was less when compared to the non-ketogenic diet group [28].

Myth #5: A Ketogenic Diet Causes Losses of Bone Mineral Density and Increases Osteoporosis Risk

Some people claim that ketogenic diets cause osteoporosis, due to making blood acidic and leeching minerals from the bones. However, this theory has a few problems. For example, under normal circumstances the pH (level of acidity) of the blood does not change depending on what diet you eat. The blood pH is tightly controlled within a very narrow span—or you’d die!

The role of ketogenic diets and bone health has been tested at least three times in the past decade.  All three studies told a group of people to go on a ketogenic diet or a higher carbohydrate diet and then followed them for up to two years [22,35,36].  The results were the same in all three studies. Following a ketogenic diet did not adversely affect bone health.


Ending the Myths

To those of you in the ‘ketogenic cult’ claiming that ketogenic diets are like magic and will fix all aspects of your life and health—please slow down. To those of you who clamor that ketogenic diets are taking our nation’s health to hell in a handbasket—please take it down a few notches.

A ketogenic diet is the best diet for some people, and is not a good choice for others. The scientific evidence presented in this article clearly demonstrated the following:

  • Ketogenic diets do not lead to a dangerous metabolic state of ketoacidosis
  • Ketogenic diets are not superior to other types of diets (when calories and protein is controlled)
  • Ketogenic diets are great for suppressing your appetite
  • Ketogenic diets will not melt away your muscle mass (as long as you are lifting weights!)
  • Ketogenic diets do not increase your risk for cardiovascular disease or osteoporosis



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