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9 myths about low-carb diets

9 Mythen zum Thema kohlenhydratarme Diäten

There is a lot of misinformation out there about low-carb diets. Some claim that this is the optimal human diet and that everyone should eat a low-carb diet. Others, however, say that low-carb diets are just fad diets that can't be followed long-term and are potentially harmful.

This article will take a look at 9 myths about low-carb diets.

1. low-carb diets are purely fad diets

In some ways, the term "fad diet" has lost its original meaning. In the past, this term was used to describe crash diets that enjoyed short-term popularity. Today, however, the term is often misused by people to describe diets with which they disagree.

And even today, many people still refer to low-carb diets as fad diets. However, this makes absolutely no sense, as numerous scientific studies have shown that low-carb diets can be quite effective.

Low-carb diets have been popular for decades. In fact, the first Atkins book was published in 1972, 5 years before the first low-fat diet guidelines were published. If we look even further back in time, the first book on a low-carb diet was published in 1863 and was already very popular back then.

When something has been around for so long and is supported by scientific research, trying to dismiss it as a fad is nothing more than a dishonest attempt to avoid discussion.

Summary: Low carbohydrate diets have been around for decades and their benefits are supported by numerous high quality human studies. Dismissing such diets as fad diets is therefore simply wrong.

2. it is difficult to stick to low-carb diets

It is often argued that low-carbohydrate diets cannot be maintained in the long term because they restrict the consumption of widely consumed food groups. It is claimed that this leads to a sense of restriction that causes people to give up their diet and quickly regain the lost weight. While this makes sense, the truth is that ALL diets involve restriction of one kind or another. Some restrict the consumption of certain food groups or macronutrients, while others restrict calories.

The great thing about a low-carb diet is that it leads to a reduction in appetite, so people can eat until they are full while still losing weight (1, 2). Compare this to a calorie restricted diet where you can't really eat as much until your hunger is satisfied and you feel hungry all the time. Being hungry all the time and never being allowed to eat until you feel satisfied...that's something most people won't be able to sustain in the long run.

The bottom line is that scientific data does not support the claim that low-carb diets are harder to stick to than other diets. I looked at 19 studies that compared low-carb and low-fat diets, indicating how many people completed the study in the low-carb and low-fat groups. Although the results were mixed, it was found that on average more subjects from the low-carb groups persisted to the end of the studies.

The average for low-carb diets was 79.51% compared to 77.72% for the low-fat diets. While this may not be a huge difference, these figures show that it is at least not harder to stick to low-carb diets compared to low-fat diets.

Summary: Scientific research does not support the statement that it is harder to stick to low-carb diets. If there is a difference to other diets, then these diets tend to be easier to maintain than low-fat diets.

3. most of the weight lost is water

The body stores significant amounts of carbohydrates in the muscles and liver. These carbohydrates are stored in the form of glycogen - a storage form of glucose. Glycogen is used to supply the body with glucose between meals.

Glycogen stored in the liver and muscles tends to bind some water. If you reduce your carbohydrate intake, your glycogen stores will be depleted and you will lose significant amounts of water. In addition, low-carbohydrate diets lead to a significant reduction in insulin levels. When insulin levels drop, the kidneys excrete excess sodium and water from the body (3, 4). For this reason, low-carbohydrate diets lead to a substantial and almost immediate reduction in water weight.

This is often used as an argument against low-carbohydrate diets and it is claimed that the only reason for the weight loss advantage of these diets is such a reduction in water weight. However, this is not the case. Low-carbohydrate diets do reduce water weight, but studies also show that they cause a greater reduction in body fat - particularly in the liver fat and abdominal area, where unhealthy belly fat is located (5, 6).

A six-week study on low-carbohydrate diets showed that subjects lost 3.4 kilos of fat while gaining 1.1 kilos of muscle (7). Furthermore, reducing water weight is a positive thing. It makes no sense to use this as an argument against low-carb diets. Who wants to carry around 5 to 10 pounds (or more) of excess water if they don't have to?

Summary: People who start a low-carb diet initially excrete larger amounts of water. However, they also lose body fat, particularly in the liver and abdominal area.

4. low-carb diets are bad for your heart

Low carbohydrate diets tend to be high in cholesterol and fat - including saturated fat. For this reason, many people claim that these diets must increase cholesterol levels and the risk of heart disease.

However, recent studies have shown that neither dietary cholesterol nor saturated fat has a significant effect on heart disease risk (8, 9, 10, 11). Contrary to what is often claimed, low-carbohydrate diets can actually improve most of the major risk factors for heart disease (12):

  • Blood triglyceride levels decrease significantly (13, 14).
  • The levels of the "good" HDL cholesterol increase (15, 16).
  • Blood pressure tends to fall (17, 18).
  • Existing insulin resistance decreases, which leads to reductions in blood sugar and insulin levels (19, 29).
  • Inflammation can decrease (21).

LDL cholesterol levels do not increase on average and LDL particle size tends to change from small and dense (which is bad) to large LDL particles - a pattern that has been associated with a reduced risk of heart disease (22, 23).

However, studies mainly look at averages and there are some individuals who experience significant increases in LDL cholesterol levels while on a low-carbohydrate diet. These individuals should take steps to lower their cholesterol levels.

Summary: There is no evidence that dietary cholesterol and saturated fat are harmful, and studies conducted with low-carbohydrate diets show that they can improve several risk factors for heart disease.

5. low-carb diets only work because people eat fewer calories

Many people claim that the only reason people lose weight on low-carb diets is because they reduce their calorie intake. While this is true, it doesn't tell the whole story. The primary weight loss benefit of low-carb diets is that the weight loss is automatic.

People feel so full that they end up eating less food without counting calories or controlling their portion sizes. This appetite-reducing effect is so strong that studies comparing low-carb and low-fat diets often only need to actively reduce calories in the low-fat group to get comparable results.

And even when calorie intake is restricted in the low-fat group, the low-fat group usually loses more weight...sometimes up to two to three times as much (24, 25)!

In addition, people sometimes don't realize that low-carb diets are not just about weight loss. These diets are also very effective when it comes to reducing/relieving certain health problems such as metabolic syndrome, type 2 diabetes and epilepsy (26, 27, 28). In these cases, the health benefits go far beyond calorie restriction.

It should also be noted that low-carbohydrate diets have a slight metabolic advantage. They tend to be high in protein, which boosts metabolism (29, 30).

Summary: It is true that low-carbohydrate diets lead to a reduction in calorie intake. The fact that this happens subconsciously is a major advantage. Low-carbohydrate diets also have metabolic benefits that go far beyond calories.

6. low carbohydrate diets reduce your consumption of healthy plant foods

A low-carb diet is not a carbohydrate-free diet. It's a myth that reducing your carbohydrate intake means you need to eat less plant foods. In fact, you can eat a large amount of vegetables, berries, nuts and seeds without exceeding 50 grams of carbohydrates per day.

Apart from that, eating 100 to 150 grams of carbohydrates per day is still considered low-carb. This amount leaves plenty of room for several portions of fruit a day and can even allow for small amounts of healthy starches such as potatoes or oatmeal.

Personally, I never eat as many vegetables as I do during a low-carb eating phase. This meets my body's needs for vitamin C, potassium, fiber and other key nutrients found in large quantities in plants. Pretty much every book on low-carb diets recommends eating large amounts of healthy plant foods, especially vegetables.

Summary: It is possible to consume large amounts of low carbohydrate plant foods as part of a low carbohydrate diet, even with a very low carbohydrate intake. Vegetables, berries, nuts, and seeds are all good examples of healthy plant foods that are low in carbohydrates.

7 "Ketosis" is a dangerous metabolic state

There is a lot of confusion about the state of ketosis. When we eat very little carbohydrate (such as less than 50 grams per day), our insulin levels drop and a lot of fat is released from fat cells. When the liver is flooded with fatty acids, it starts to convert them into substances called keto bodies or ketones.

These are molecules that are able to cross the blood-brain barrier and provide the brain with energy during periods of starvation or when we are not eating carbohydrates.

However, many people seem to confuse the state of ketosis with ketoacidosis. The latter is a dangerous metabolic state that mainly occurs in uncontrolled type 1 diabetes. It involves flooding the bloodstream with massive amounts of ketones - enough to make the blood acidic. Ketoacidosis is a very serious thing and can be fatal.

However, this has no relevance to the type of ketosis caused by low-carbohydrate diets, as ketosis is a healthy metabolic state. For example, such ketosis has been shown to have therapeutic effects in epilepsy and is also being investigated as a potential treatment for brain diseases such as Alzheimer's and as a supportive treatment for cancer (27, 28, 29).

Ketoacidosis is a very dangerous thing, but ketosis is a good thing. They are completely different things.

Summary: A very low carbohydrate diet leads to a beneficial state called ketosis. This is not the same as ketoacidosis, which is dangerous and only occurs in uncontrolled diabetes.

8. the brain needs glucose (carbohydrates) to function

Many people mistakenly believe that the brain cannot function without carbohydrates during a diet. It is claimed that carbohydrates are the preferred energy source for the brain and that the brain needs about 140 grams of carbohydrates per day. This is partly true. Some cells in the brain cannot use any other energy source than glucose.

However, other parts of the brain are very capable of using ketones for energy. When carbohydrate intake is reduced sufficiently to induce ketosis, a large part of the brain stops using glucose and starts using ketones instead.

However, this still means that even when there are large amounts of ketones in the blood, some parts of the brain still need glucose. This is where a metabolic pathway known as gluconeogenesis comes into play. If we do not consume enough carbohydrates, then the body (primarily the liver) can produce glucose from protein and by-products of fat metabolism.

Due to ketosis and gluconeogenesis, we do not need to consume a single gram of carbohydrate - at least not to supply the brain with energy.

And after the initial adaptation phase, many people even report better brain function during a low-carb diet.

Summary: During a low-carb diet, part of the brain can use ketones for energy. The body can also produce the small amounts of glucose that are still needed by other parts of the brain.

9. low carbohydrate diets will ruin your physical performance

Most athletes eat a high carbohydrate diet and many people believe that carbohydrates are essential for physical performance. It is true that a reduction in carbohydrate intake can initially lead to reduced performance. However, this condition is usually only temporary. It can take some time for the body to get used to burning fat instead of carbohydrates.

Many studies have shown that low-carbohydrate diets can even have a positive effect on physical performance, especially in endurance sports, as long as people are given a few weeks to adapt to this new way of eating (30, 31, 32, 33).

There are also studies showing that low-carbohydrate diets can have positive effects on muscle mass and strength (34, 35).

Summary: Low-carbohydrate diets do not have a devastating effect on physical performance for most people. However, it can take a few weeks for the body to adapt to this type of diet.


At the end of the day, low-carb diets can have significant health benefits. They are very effective for obese people and those suffering from metabolic syndrome or type 2 diabetes.

However, while low-carb diets can be beneficial, they are not the perfect answer for everyone. Different people may require different dietary approaches.




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