Myth 1: Carbs are an essential nutrient for good health.
This is the favorite phrase of the American Dietetic Association members. But as much as they like to repeat this, it's just not true scientifically. Essential nutrients are nutrients which your body cannot make, so they have to be obtained on a daily basis from your food sources.
There are essential proteins, and essential fatty acids, but there is no such thing as an essential carbohydrate. Your body can make all the carbohydrate it needs from protein and the glycerol that is part of fatty acids. However, the fact that they aren't essential doesn't mean that everyone should stop eating them completely.
There are people who can tolerate eating large amounts of carbohydrates on a daily basis. However, there are also people who can't. These people have a low tolerance for carbohydrates, and if they eat large quantities of them, they develop metabolic disorders like insulin resistance and diabetes.
If you can eat that many carbohydrates without developing any metabolic issues, go for it. I'm just saying that humans can get by without eating carbs and continue to maintain perfect health, because the body can use ketone bodies from fatty acids for fuel, if no carbohydrates are eaten.
Comment: Just a note that there is a lot of damage done by carbohydrates that takes many years to surface. So just because someone may think that they can tolerate large amounts of carbs because they don't see any negative affect now, doesn't mean that damage isn't being done.
And here's an interesting fact: Dietitans rely heavily on the Dietary Reference Intakes for Energy, Carbohydrate, Fiber, Fat, Fatty Acids, Cholesterol, Protein, and Amino Acids (Macronutrients)(2005) in providing nutritional advice. But even this publication says on page 275:
"The lower limit of dietary carbohydrate compatible with life apparently is zero, provided that adequate amounts of protein and fat are consumed."Myth 2: There's a danger of vitamin deficiencies with low carbohydrate diets. You definitely won't get enough Vitamin C.
Not true, see my Facts about Vitamins page and my Vitamin C Deficiency page.
Myth 3: Ketogenic diets cause your body to go into ketosis, which is dangerous.
Not true, the person who says this is confusing ketosis with ketoacidosis. For more information, see my ketosis and ketoacidosis pages.
Myth 4: Your kidneys will sustain damage from the high protein consumption.
Whenever someone says this, I know they have never read any of the low carb, ketogenic diet books available. They are just parroting what they've heard from someone else. Low carb diets, and especially ketogenic diets, are NOT high protein diets. The are HIGH FAT diets, with moderate protein consumption. And, anyway, if you are healthy with no prior kidney disease, eating extra protein will NOT harm your kidneys. See this study.
Myth 5: A low carb, high protein diet will cause the body to excrete calcium, and result in osteoporosis.
As stated in Myth 4, a ketogenic diet is NOT a high protein diet. It's a high fat, moderate protein diet. Regardless of that fact, protein consumption is essential for good bone health. This paper indicates that in addition to calcium in the presence of adequate vitamin D, proteins are a key nutrient in the prevention of osteoporosis. In addition, the paper states that low protein intake is often observed in patients with hip fractures and that a deficiency in dietary protein causes marked deterioration of bone mass and strength. So, in fact, a higher protein intake correlates to a stronger, denser bones. This paper and this paper also support these statements.
So what does cause bone loss? There are several suspects:
- A magnesium deficiency
- High fructose consumption
- Gluten intolerance associated with grain consumption
- Vegetable oil consumption, especially corn oil
This, I think is the biggest myth associated with low carb, ketogenic diets. It's based on the lie that saturated fat and cholesterol cause arteriosclerosis and heart disease. There has never been any scientific study published or unpublished which links cholesterol and saturated fat to heart disease. Shocking but true. In fact, this 2010 meta-analysis distinctly destroys any link between heart disease and saturated fat.
And this study showed that low carb diets actually improve heart disease markers over other types of diets.
And here's another study which looks directly at how a ketogenic diet favorably affects blood test results for heart disease.
And one more recent study from Johns Hopkins University School of Medicine confirms that a higher fat, low carb diet is not detrimental to vascular health AND results in faster weight loss.
The authors confirmed that
"Low-carb dieters showed no harmful vascular changes, but also on average dropped 10 pounds in 45 days, compared to an equal number of study participants randomly assigned to a low-fat diet. The low-fat group, whose diets consisted of no more than 30 percent from fat and 55 percent from carbs, took on average nearly a month longer, or 70 days, to lose the same amount of weight."In contrast, there are tons of studies showing that a high carbohydrate diet and elevated blood sugar and insulin are highly associated with inflammatory heart disease. For instance, consider a blood test called the Hemoglobin A1C (i.e., the HbA1c). It's basically a measure of your average blood sugars for the 3 months preceding the test.
In the EPIC study, the authors looked at the relationship between the Hemoglobin A1c test results and the risk of heart attack. The results were very clear: the higher a person's HbA1c levels, (i.e., the higher the average blood sugars) the higher the risk of heart attack. See this post and the study results here.
Myth 7: Antioxidants and phytonutrients from plants are important for good health, and a ketogenic diet lacks these chemicals.
Incorrect. See my Antioxidant Foods page.
Myth 8: Complex Carbohydrates are the "good carbs" and it's healthy to include them in your diet.
Not so much. See my Complex Carbs page.
Myth #9: Low carb diets cause muscle wasting.
Not true. In fact, low carb diets are better at preserving and even increasing lean muscle mass. In this study published in 1984, a team of scientists from MIT and Harvard studied two groups of overweight women. They put one group on a low carb diet, and the other group on a high carb diet. Each diet allowed 700 calories per day. Even with a severe caloric deficit, the greater percentage of protein consumed on the low carb diet and the effects of ketosis resulted in a greater retention of muscle mass for the subjects on the low carb diet. In other words, the subjects on the high carb diet loss more muscle mass because the carbs they were eating displaced some of the protein that would have helped them retain muscle mass.
This phenomenon of how dietary protein helps the body retain muscle mass has been shown many times over in various studies on very low calorie diets which include adequate protein and muscle building substrates such as sodium and potassium. See this study, this study, and this study.
This general "muscle wasting" assertion often comes from trainers and dietitians who really have not studied the science on muscle preservation. They will tell you that the brain requires at least 100 grams of carb per day and if you don't get those carbs in the diet, your body will break down your muscles to get it. This is true when one's diet is high carb, and no ketone bodies are available as an alternative source of brain fuel.
But for a person who is adapted to a low carb, ketogenic diet, ketosis provides fuel in the form of ketone bodies for the brain, and the requirement for glucose drops to only about 40 grams per day. The body can easily make this amount from dietary protein and glycerol from the break down of fatty acids.
Myth #10: The weight loss from low carb, ketogenic diets is not real. It's only water loss.
It is true that in the initial week or so of a ketogenic diet, some of the weight loss will be water loss, as your body adapts to the new lower carb diet, and gets busy re-engineering the cellular enzymes needed to burn fat instead of carbohydrate for fuel.
It has been known for years that fasting in general, and cutting carbohydrate intake (which is a milder form of fasting, metabolically speaking) results in water loss because blood sugar, insulin, and glycogen stores (excess sugar stored in your muscles and liver) are reduced. As blood sugar and insulin levels come down, the kidneys dump excess water and sodium from the body.
Put another way, water retention and high blood pressure are common side effects of a high carb diet, because a high carb diet causes the kidneys to retain salt, which causes the body to retain water. Going on a low carb, ketogenic diet is an excellent way to reduce water retention and blood pressure.
After a week or so on a ketogenic diet, your body will become "keto-adapted", and water loss will stabilize, as long as you are getting enough sodium and other minerals to replace the ones lost in the bathroom. At this point, fat loss accelerates and becomes the primary source of fuel.
The water loss effects of dizziness and weakness at the beginning of a low carb diet can be avoided by making sure you get plenty of salt (at least 5g/day) and extra potassium and magnesium in your diet.
In the MIT/Harvard study discussed previously, the low carb group participants were given 5 grams of salt each day to offset the natural loss associated with lower carb consumption. Note that there was no difference in water loss between the low carb and the high carb group at the conclusion of the study, and both groups lost the same amount of weight.
In addition, this survey showed that in just one low carb internet group, over 1400 people had lost weight and kept if off using a low carb diet.
Myth #11: Low carb, ketogenic diets are low in fiber, and so detrimental to your colon.
Incorrect. People who follow ketogenic diets eat more fibrous vegetables than they did when following the standard American diet. In fact, fibrous vegetables such as cabbage, spinach and salads make up a large part of the carb calories allowed on a ketogenic diet. See the results of this survey.
That's my stab at trying to kill the most pervasive low carb dieting myths. I encourage you to read the information and links I've included and decide for yourself if low carb dieting is unhealthy.