However, most of these negative views are entirely false and the science doesn’t support them.
This article looks at ten of the most common myths and examines how they stack up.
What is the truth?
1. Low Carb Diets Are Dangerous Because They Cut Out “Entire Food Groups”
We often hear how important a “balanced diet” is and that we shouldn’t cut out “entire food groups.” In other words, the underlying message is that low carb diets are not ideal since they tend to restrict cereal grains.
Particularly, the American Heart Association tells us that a heart-healthy diet should include 6-8 servings of whole grains every day (1).
There are a couple of issues with this;
- Most people are not eating real whole grains. Instead, they are eating ultra-processed cereals like cheerios, fruit loops, and also refined carbs from bread, rice, and pasta.
- We can find all the nutrients present in genuine whole grains in larger concentrations in fruits and vegetables.
Regarding the first point, refined carbs are associated with an increased risk of almost every chronic disease out there. There is a firm link with the etiology of type 2 diabetes, cancer, Alzheimer’s, and cardiovascular disease (2, 3, 4, 5).
So, all low carb diets are doing (compared to the majority) is replacing these refined grains which are damaging to health. Regarding true whole grains, we can find all the nutrients they contain—often in far greater quantities—in fruit and vegetables.
2. Low Carb Diets Lead to Vitamin and Mineral Deficiencies
The claim that low carbohydrate intake leads to micronutrient deficiencies stems from the general avoidance of grains and starchy carbohydrates.
However, once again there is nothing particularly unique about the nutrients these foods offer.
The truth is that vitamin and mineral deficiencies can develop on low carb, vegan, paleo, low fat, or any other diet.
Nutrient density depends on the overall context of the diet and precisely what foods someone is eating.
Do you exist solely on bulletproof coffee for breakfast and “fat bombs” throughout the day?
Well, that could be problematic.
Conversely, a low carb diet featuring meat, fish, nuts, veggies, and fruit is likely to be very nutrient dense.
Here’s an example;
|4-egg Cheese & Onion Omelet||5oz Mackerel Fillet||8 oz Strip Steak|
|1 tbsp butter||20 Olives||1 cup Spinach|
|3oz Blueberries||1 Yellow Pepper|
This plan only comes to 1647 calories, so there will probably be room to spare depending on gender and energy requirements.
As you can see from the data below, it is also incredibly rich in vitamins and minerals;
Can we get the same nutrient density in 1647 calories if we are eating cereals, sandwiches, and pasta?
It’s possible, but it would sure be a lot harder.
3. Diets High in Saturated Fat Are Artery-Clogging and Cause Heart Disease
There is a myth that implies low carb diets are a risk factor for heart disease because they are higher in saturated fat.
But is saturated fat bad for you?
Put bluntly, saturated fat is not the enemy, and the true villains are likely refined carbohydrates, sugar, trans fat, and vegetable oils.
- Significantly increasing “good” HDL
- Reducing triglyceride levels
- Sometimes slightly increasing LDL or sometimes having no effect, but making the LDL particles “less atherogenic.”
In any event, most of the latest science shows that the traditional marker of heart disease risk—LDL versus HDL—is suboptimal (13).
Many cardiovascular disease researchers assert that the triglyceride to HDL ratio is the most closely aligned risk factor. High triglycerides and low HDL is bad, while low triglycerides and higher HDL should be the aim.
4. Our Brain Needs At Least 130g of Carbohydrate Per Day
Some people assert that the brain cannot function without an adequate supply of glucose from carbohydrate.
A figure often thrown around is 130g of carbs as the bare minimum requirement for brain-glucose.
Want to consume less carbohydrate than this? Then, according to popular myth, we won’t have enough glucose to maintain normal brain function.
Is it true?
This low carb myth completely ignores the process of gluconeogenesis, a metabolic pathway that converts protein to glucose.
Additionally, another key point is that our brain can run on two forms of energy. The first of these is glucose, metabolized from carbohydrate, and then there are ketone bodies from metabolizing fat (ketones).
Our body—and brain—can burn these ketones for fuel, and studies show they can be very beneficial for brain health. In particular, they seem to be advantageous for the treatment of various brain conditions such as epilepsy and certain brain tumors (18, 19).
Some studies even show that our brain cells can function more efficiently when using ketones rather than glucose (20).
5. Low Carb is an Unsustainable Fad Diet
It’s not uncommon for any diet that doesn’t meet social norms to come under the “fad diet” tag.
Interestingly, this claim tends to be thrown at most “real food” diets such as LCHF and paleo.
The question is; how long have humans been consuming meat, fish, nuts, vegetables, and fruits?
Only a few million years.
Now, how long have we been eating random mixtures of powdered sugar, flour and oils in brightly colored boxes?
Maybe for the last century at a max.
It’s quite ridiculous that the first of these gets called a “fad,” while diets full of industrial junk foods do not.
If we’re talking about the worst diets ever, then the modern Western diet probably tops the lot.
Regarding sustainability, studies show that low carb diets tend to be more sustainable than low fat eating plans. Most significantly, low carbohydrate diets appear to “spontaneously reduce calorie intake” (21, 22, 23).
6. Low Carb Diets Are Unsuitable For Sports and Athletes
It may sound familiar by now, but apparently, we cannot perform exercise or sports well on a low carb diet.
Because, apparently, glucose is “essential” for energy.
The truth is that the vast majority of gym-goers and athletes are consuming a high-carbohydrate diet.
If they suddenly switch to low carb, then yes, there will be an adjustment period as their body adapts to a new metabolic state.
However, once the body adapts to burning fat for fuel rather than carbohydrate (approximately three weeks), physical performance improves progressively (24).
Additionally, emerging science suggests that ultra-low carb diets have the following performance benefits;
- Fat-adapted athletes have a higher rate of fat oxidation than carb-fuelled athletes (25)
- Allow for a reduction in body weight despite maintaining or improving strength, power, and muscle mass (26)
- Ultra-low carb diets increase the capacity for exercise in physically unfit individuals (27)
For more on this topic, see this article on the performance benefits of being keto adapted.
7. Being in Ketosis Isn’t safe
An often quoted reason for this belief is that “they can cause ketoacidosis.”
However, confusion exists between ketosis and ketoacidosis – and there is a world of difference between the two.
Is ketosis dangerous?
Ketosis is a perfectly natural metabolic state during which the body safely burns fat (ketones) for energy, and it takes place in times of very low glucose availability (28).
On the other hand, diabetic ketoacidosis occurs when levels of ketone bodies in the blood of diabetics become excessively high. Ketoacidosis is a medical emergency and the largest cause of death in young adults with type 1 diabetes (29, 30).
Despite this, ketosis cannot lead to ketoacidosis in healthy individuals. The body has a feedback loop which recognizes when ketones start becoming high, and releases a small amount of insulin. This insulin release lowers the concentration of ketones in the blood (31).
8. Low Carb Diets Are Dangerously Low in Fiber
Presumably due to the lack of cereal grains in the diet, there is a mistaken belief that low carb diets don’t contain any fiber.
So, how can we get enough fiber on a low carb diet?
Sometimes a picture says it best, so here’s one on this topic;
As the picture shows, fruits and vegetables can provide just as much—if not more—fiber than grains.
Furthermore, green leafy vegetables such as spinach and kale are large sources of fiber, and they are very low in carbs.
Is a high fiber diet good for you?
Generally speaking, fiber-containing foods tend to be healthy, but a point often overlooked is that too much fiber could be harmful.
Some people function well on a high fiber diet, while others do not.
9. Low Carb Diets Are Too High in Cholesterol
After decades of warnings to restrict egg consumption, some people still have an inherent fear of cholesterol in the diet.
Some (vegan) people even state that eating an egg is “as bad as smoking.”
The truth about cholesterol
At the end of the day, dietary cholesterol in our food is very different to plasma cholesterol in our blood.
Firstly, our liver produces approximately 1-2 grams of cholesterol per day. Should we consume some dietary cholesterol, the liver will produce a little less.
Cholesterol is nothing to fear, and the latest edition of the dietary guidelines for Americans even admits this. The 2015-2020 guidelines state that cholesterol is “no longer a nutrient of concern for overconsumption” (33, 34).
Furthermore, most cholesterol-rich foods contain vital nutrients such as vitamin D and choline.
Eggs, liver, and seafood are some of the most nutritious foods on earth – and they are all high in cholesterol.
They are good for you too.
10. All Carbohydrate is Harmful
This myth is here for a little balance.
While excessive amounts of carbohydrate can cause metabolic havoc, whole food sources are not specifically harmful.
A low carb diet isn’t a no carb diet, and if you want to eat some fruit, starchy veggies, or even sweet potatoes – that’s fine. Everyone is a little different, so do whatever feels the best for you.
The caveat here is people with diabetes or any significant degree of insulin resistance.
The critical low carb myths floating around are mostly based on outdated science and easy to disprove.
Providing it is properly implemented, a low carb diet is extremely nutrient-dense and goes a long way to improving health.