There is a lot of misinformation about low-carb diets.
Some claim that it’s the optimal human diet, while others consider it an unsustainable and potentially harmful fad.
Here are 9 common myths about low-carb diets.
The term “fad diet” was used for crash weight loss diets that enjoyed short-term popularity.
Today, it’s often misused for diets that don’t have common cultural acceptance, including low-carb diets.
However, a low-carb way of eating has been shown to be effective in over 20 scientific studies.
Plus, it has been popular for decades. In fact, the first Atkins book was published in 1972, five years before the first set of low-fat dietary guidelines in America.
Looking even further back, the first low-carb book was published by William Banting in 1863 and was wildly popular at the time (1).
Considering the long-term and scientifically proven success of low-carb diets, dismissing this way of eating as a fad seems far-fetched.
SUMMARY Fad diets enjoy short-term popularity and success. In contrast, the low-carb diet has been around for decades and is supported by over 20 high-quality human studies.
Opponents often claim that low-carb diets are unsustainable because they restrict common food groups.
This is said to lead to feelings of deprivation, causing people to abandon the diet and regain weight.
Still, keep in mind that all diets restrict something — some certain food groups or macronutrients, others calories.
In contrast, on a calorie-restricted diet, you’re less likely to eat until you’re fully satisfied and may end up being hungry all the time — which is unsustainable for most people.
Scientific evidence does not support that low-carb diets are harder to stick to than other diets.
SUMMARY Science does not support the idea that low-carb diets are hard to stick to. In fact, they allow you to eat until satisfied while still losing weight, which is more sustainable than calorie-restricted diets.
Your body stores a lot of carbs in your muscles and liver.
It uses a storage form of glucose known as glycogen, which supplies your body with glucose between meals.
Stored glycogen in your liver and muscles tends to bind some water.
When you cut carbs, your glycogen stores go down, and you lose a lot of water weight.
For these reasons, low-carb diets lead to a substantial and almost immediate reduction in water weight.
This is often used as an argument against this way of eating, and it’s claimed that the only reason for its weight loss advantage is the reduction in water weight.
For example, one 6-week study on low-carb diets showed that participants lost 7.5 pounds (3.4 kg) of fat but gained 2.4 pounds (1.1 kg) of muscle (
SUMMARY People who eat a low-carb diet shed a lot of excess water but also body fat, especially from the liver and abdominal area.
Low-carb diets tend to be high in cholesterol and fat, including saturated fat.
For this reason, many people claim that they raise blood cholesterol and increase your risk of heart disease.
Most importantly, low-carb diets may improve many important heart disease risk factors by (13):
- significantly decreasing blood triglycerides (
- increasing HDL (good) cholesterol (
- lowering blood pressure (
- decreasing insulin resistance, which reduces blood sugar and insulin levels (
- reducing inflammation (
What’s more, levels of LDL (bad) cholesterol generally don't increase. Plus, these particles tend to change from harmful, small, dense shapes to larger ones — a process linked to a reduced risk of heart disease (22,
Still, keep in mind that these studies mostly look at averages. Some individuals may experience major increases in LDL (bad) cholesterol on a low-carb diet.
If this is the case for you, you can adjust your low-carb way of eating to get your levels down.
SUMMARY There is no evidence that dietary cholesterol and saturated fat cause harm, and studies on low-carb diets show that they improve several key risk factors for heart disease.
Many people claim that the only reason people lose weight on low-carb diets is due to reduced calorie intake.
This is true but doesn’t tell the whole story.
The main weight loss advantage of low-carb diets is that weight loss occurs automatically.
People feel so full that they end up eating less food without counting calories or controlling portions.
In these cases, the health benefits go beyond reduced calorie intake.
SUMMARY Though low-carb diets lead to reduced calorie intake, the fact that this happens subconsciously is a big benefit. Low-carb diets also aid metabolic health.
A low-carb diet is not no-carb.
It’s a myth that cutting carbs means that you need to eat fewer plant foods.
In fact, you can eat large amounts of vegetables, berries, nuts, and seeds without exceeding 50 grams of carbs per day.
What’s more, eating 100–150 grams of carbs per day is still considered low-carb. This provides room for several pieces of fruit per day and even small amounts of healthy starches like potatoes and oats.
It’s even possible and sustainable to eat low-carb on a vegetarian or vegan diet.
SUMMARY You can eat plenty of plant foods even with a very low carb intake. Vegetables, berries, nuts, and seeds are all examples of healthy plant foods that are low in carbs.
There is a lot of confusion about ketosis.
When you eat very few carbs — such as fewer than 50 grams per day — your insulin levels go down and a lot of fat is released from your fat cells.
When your liver gets flooded with fatty acids, it starts turning them into so-called ketone bodies, or ketones.
These are molecules that can cross the blood-brain barrier, supplying energy for your brain during starvation or when you don’t eat any carbs.
Many people confuse “ketosis” and “ketoacidosis.”
The latter is a dangerous metabolic state that mainly happens in unmanaged type 1 diabetes. It involves your bloodstream getting flooded with massive amounts of ketones, enough to turn your blood acidic.
Ketoacidosis is a very serious condition and can be fatal.
However, this is completely unrelated to the ketosis caused by a low-carb diet, which is a healthy metabolic state.
SUMMARY A very-low-carb diet leads to the beneficial metabolic state of ketosis. This is not the same as ketoacidosis, which is dangerous but only happens in unmanaged type 1 diabetes.
Many people believe that your brain cannot function without dietary carbs.
It’s claimed that carbs are the preferred fuel for your brain and that it needs about 130 grams of carbs per day.
This is partly true. Some cells in your brain cannot use any fuel besides carbs in the form of glucose.
Yet, other parts of your brain are perfectly capable of using ketones.
If carbs are reduced sufficiently to induce ketosis, then a large part of your brain stops using glucose and starts using ketones instead.
That said, even with high blood ketone levels, some parts of your brain still need glucose.
This is where a metabolic pathway called gluconeogenesis becomes important. When you don’t eat carbs, your body — mostly your liver — can produce glucose out of protein and byproducts of fat metabolism.
Therefore, because of ketosis and gluconeogenesis, you don’t need dietary carbs — at least not for fueling your brain.
After the initial adaptation phase, many people report having even better brain function on a low-carb diet.
SUMMARY On a low-carb diet, a part of your brain can use ketones for fuel. Your body can then produce the little glucose that other parts of your brain still need.
Most athletes eat a high-carb diet, and many people believe that carbs are essential for physical performance.
Reducing carbs indeed leads to reduced performance at first.
However, this is usually only temporary. It can take your body a while to adapt to burning fat instead of carbs.
SUMMARY Low-carb diets are not detrimental to physical performance for most people. However, it can take a few weeks for your body to adapt.