What is a Low Carb Diet?
A low-carb diet is an eating pattern in which carbohydrates are either completely avoided or consumed in very small amounts. However, there is no exact definition of how many grams of carbohydrates per day constitute a low-carb diet.
Currently, the recommended proportion of carbohydrates by most nutrition societies, such as the WHO, is around 50% - 60% of the daily requirement. In contrast, with low carb, the daily carbohydrate intake is significantly below these 50% to 60%.
Low-carb diets include, for example, the ketogenic diet, the Atkins diet, the carnivore diet, as well as some other well-known diet forms. Thus, low carb is more of an overarching term for many different dietary approaches and modern diet trends.
With low carb, one avoids foods with a high carbohydrate content such as bread, pasta, potatoes, sugar, oats and sweets. Foods with moderate carbohydrate content such as dairy products, berries, avocado, and processed meats are consumed only in very small amounts. Instead, a low carb diet relies on meat, fish, eggs, salads, low-carb vegetables, oils, and nuts.
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What Happens in Our Body with a Low Carb Diet?
1) Insulin Secretion
When we consume short-chain carbohydrates, our insulin levels initially rise more sharply than with a meal consisting solely of proteins and fats. The constant rise in insulin can be very taxing on our pancreas, as it has to work continuously to produce and release the hormone insulin. By avoiding starchy and sugary carbohydrates, we can relieve our pancreas. Additionally, lower insulin secretion leads to better-regulated hunger and satiety hormones. For this reason, a low-carb diet is often advocated, especially for individuals with diabetes or metabolic disorders. For a healthy, active individual with substantial muscle mass who engages in both endurance and resistance workouts, carbohydrates are not detrimental to their health.
2) Glycolysis
All the food we consume is converted into a substance called glucose in our bodies. However, carbohydrates can be converted into glucose particularly quickly, much faster than proteins and fats. When we primarily consume carbohydrates, it often leads to an excess of glucose in our bodies. If our glycogen stores in muscles and liver are already full, the excess glucose is converted into fat and then stored (in the form of fat deposits). In a low-carb diet, we have less glucose to store, so our body draws glucose from other sources of energy.
3) Gluconeogenesis
Carbohydrates are not essential components of our diet because the body can produce carbohydrates itself if none are supplied from outside. This process is called gluconeogenesis, during which carbohydrates are produced or converted from other components of the diet. However, we need glucose particularly for our cognitive function, that is, for our brain. Therefore, some researchers suspect that a low-carbohydrate diet is associated with reduced brain performance, although this is still debated.
4) Ketosis
After consuming very few carbohydrates for several days, the body switches to what is called "starvation metabolism." This means the body produces so-called ketone bodies from our body's own fat tissue and uses them for energy. So, more of our body's own fat is consumed and metabolized. This state is called "ketosis" or "ketogenesis."
Does Low Carb help with Weight Loss?
It's not uncommon to hear phrases like "I want to lose weight, so I'm avoiding carbohydrates in the evening" or "Potatoes, pasta, and bread make you fat."
However, there is still some need for clarification, and we cannot simply generalize and say "Low carb helps with weight loss!"
First of all, let's be clear: Carbohydrates themselves do not make you any fatter or thinner than fats do.
What makes you gain weight is consistently eating more than you expend, regardless of what the energy source is.
So, if you want to lose weight, ultimately, you have to pay attention to your energy balance and simply eat less than you expend.
One reason why low carb diets help many people, though, is simply because many high-calorie foods that were previously consumed are suddenly eliminated, resulting in consuming fewer calories overall. Processed foods, sweets, pastries, and ready-made products, in particular, have a high calorie density and are excluded from a low-carb diet.
Similarly effective, however, can be integrating healthy, long-chain carbohydrates like potatoes, oatmeal, legumes, fruits, and vegetables into the diet, but still keeping an eye on your energy balance and eating less than you expend.
ATTENTION: Many people report incredibly rapid weight loss after only a few days or weeks of a low-carb diet. However, this weight loss is rarely due to fat reduction but rather simply due to water loss in the body. For every gram of glycogen (=carbohydrate) stored, an additional 4 grams of water are stored. Therefore, the number on the scale often drops dramatically in a short time with a low-carb diet, but this has nothing to do with fat reduction!
Who Should Do Low-Carb and Who Shouldn't?
The following groups of people are generally advised against Low-Carb diets:
Individuals with elevated blood lipid and uric acid levels
Those suffering from gout, kidney, or liver diseases
Children and adolescents
Pregnant and breastfeeding women
Individuals with an eating disorder
Athletes or very active individuals
For the following groups of people, a Low-Carb diet may (temporarily) be suitable:
Individuals with severe obesity or moderate obesity
People with type I and II diabetes or metabolic disorders
Individuals who suffer from constant cravings and significant insulin fluctuations
Those with Parkinson's, Alzheimer's, epilepsy, or cancer
Pro's and Con's of a Low Carb Lifestyle
Advantages | Disadvantages |
Abstinence from processed convenience foods and sweets. | Some people experience digestive discomfort, such as constipation or diarrhea, when transitioning to a low-carb diet due to changes in fiber intake and gut microbiota. |
Insulin sensitivity can be improved, which is positive for people with diabetes or metabolic disorders. | Low intake of vegetables and fruits, resulting in fewer vitamins and minerals. |
Reduced cravings for sugar and binge eating attacks. | It can become monotonous and one-sided and is harder to sustain during social events. |
Decrease in feelings of low mood and frequent fatigue. | Often decreased cholesterol intake, which negatively affects LDL cholesterol levels. |
Reduction in feelings of hunger due to the satiating effect of increased protein intake. | Weight loss is usually attributed to water loss, with no better long-term success than with other reduction diets. |
For some individuals, reducing carb intake can lead to lower blood pressure levels, which is beneficial for heart health. | Often not as practical for daily life and difficult for many to maintain. |
Some people report improved mental clarity and focus when following a low-carb diet, although individual responses may vary. | Decrease in mental and physical performance as carbohydrates provide the quickest energy during a "low". |
Low-carb diets have been shown to increase levels of "good" HDL cholesterol, which can reduce the risk of heart disease. | Carbohydrates are involved in the formation of the happiness hormone serotonin, so low-carb diets can lead to mood swings and bad moods. |
Conclusion on Low Carb Nutrition
Low carb is certainly not a solution for everyone, as there are also genetic differences in the metabolism of carbohydrates. Some individuals may gain weight more quickly when consuming a carbohydrate-rich diet, while others may gain weight just as quickly with an excess of other nutrients.
Personally, I recommend not adhering to a low carb diet long-term and permanently in most cases.
Carbohydrates, along with fats and proteins, are still considered main nutrients, even though they are not essential.
In my opinion, none of these three main nutrients should be completely eliminated, as they all have their validity and fulfill specific functions in the body.
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Sources of Information:
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Naude CE, Brand A, Schoonees A, Nguyen KA, Chaplin M, Volmink J. Low-carbohydrate versus balanced-carbohydrate diets for reducing weight and cardiovascular risk. Cochrane Database Syst Rev. 2022 Jan 28;1(1):CD013334. doi: 10.1002/14651858.CD013334.pub2. PMID: 35088407; PMCID: PMC8795871.
Chacón V, Cara KC, Chung M, Wallace TC. Defining "low-carb" in the scientific literature: A scoping review of clinical studies. Crit Rev Food Sci Nutr. 2024 Jan 8:1-10. doi: 10.1080/10408398.2023.2300705. Epub ahead of print. PMID: 38189653.
Astrup A, Hjorth MF. Low-Fat or Low Carb for Weight Loss? It Depends on Your Glucose Metabolism. EBioMedicine. 2017 Aug;22:20-21. doi: 10.1016/j.ebiom.2017.07.001. Epub 2017 Jul 4. PMID: 28693980; PMCID: PMC5672079.