The myths and facts about sugar

Myth no. 1: Sugar is necessary for life

Fact: Aside from some exceptions such as mother’s breastmilk, sugar is not essential for life, as the body creates a sufficient amount of it on its own.

The claim that carbohydrates are indispensable to humans and are a main source of energy is not based on any scientific findings. Carbohydrates are a primary source of energy only because they are the primary component of our diet, which is a cultural matter, not a nutritional necessity.

Our diet contains three primary nutrients – carbohydrates, fats and protein. The body cannot produce some proteins and fats, and therefore it is dependent on receiving them through food – these nutrients are thus “essential” to life. Carbohydrates and sugars are not essential, and the body can produce them.


Myth no. 2: Sugar is necessary during physical activity

Fact: The necessity to consume sugar during physical activity has never been proven, and elements of low-carb diets are used in professional sports. By using such diets, the muscles oxidize more fats and use less glucose. This also applies to patients with Type 1 Diabetes using insulin, who do not have to add as many carbohydrates during physical activity when on a low-carb diet. The risk of hypoglycemia during sports activity is also lower.


Myth no. 3: Sugar is necessary for proper brain function

Fact: Glucose is the primary fuel for the brain, but it does not necessarily have to come from simple sugars in food. Recent research has linked excessive sugar consumption with reduced ability to concentrate and mood swings.

There is no danger of an insufficient amount of glucose in the brain even with the strict ketogenic version of this diet. On this diet, the brain uses ketone bodies as fuel and its uptake of glucose decreases significantly. This change does not harm the brain; on the contrary, a ketogenic diet is used to treat epilepsy, Parkinson’s and Alzheimer’s diseases, head injuries and other neurological illnesses.


Myth no. 4: Sugar is poison

Fact: Sugar is not poison and a healthy metabolism is equipped with all the necessary enzymes and hormones to process it. In excessive amounts, however (i.e. the amounts in which most people consume sugar today), it can be harmful.

Our metabolism has developed for millions of years under completely different conditions, and the present and dramatic increase in sugar consumption therefore has certain implications.

Excessive sugar consumption not only causes tooth decay, but also leads to overweight or obesity and causes fat to be deposited on the liver, which can result in the development of metabolic syndrome, diabetes, cardiovascular diseases and some types of tumors.

What is the difference between sugars and carbohydrates?

Carbohydrates can be divided into simple (i.e. sugars) and complex forms, which include starch and fiber. The human body is able to use sugars and starch. Fiber is not absorbed and has favorable effects on slowing down the digestion of sugars and starches.

Sugars are naturally found in fruit and sweeter vegetables (which also contain fiber). Lactose is another natural sugar found in milk and dairy products.


What is starch and what role does fiber play?

Starch is made up of many molecules of glucose connected together and is broken down into glucose during digestion. Pure starch is found in white flour and products made from it (white baked goods, pasta, dumplings, cakes, etc.) or in white rice and products from potato starch. Pure starches (without fiber) have a similar effect on the metabolism and level of blood sugar as does common table sugar.
High-quality and nutritionally valuable sources of carbohydrates are those that have their natural content of fiber intact and thus contain both starch and fiber (wholegrain cereals, legumes) or natural sugars and fiber (vegetables, fruit and nuts). In addition, these foods are also a source of protein (legumes), high-quality fats (nuts), vitamins and minerals.
Nutritionally valuable grains include products from wholegrain wheat and other types of grains (rye, barley, oats), wholegrain (brown) rice, corn, buckwheat, millet, quinoa and amaranth. Legumes include peas, beans, lentils, chickpeas and soy. Carbohydrates from these sources are digested more slowly and thus blood sugar levels rise less and more slowly, as they have a lower glycemic index. Due to this fact, they are more satiating and do not induce hunger as quickly as foods with a high glycemic index.

What influences the level of glycemic index?

The glycemic index (GI) refers to the speed of carbohydrate absorption and the subsequent rise of blood sugar. The greater the speed, the higher the GI of a given food. Defining parameters for GI level are: the amount and type of sugars; composition of starches; the content of fibers, fats and proteins; ripeness of fruits; and other technological modification or cooking.


It is impossible to claim that simple sugars are harmful and complex carbohydrates are nutritiously valuable. It depends on their source, how they are prepared, and what the meal’s resulting glycemic index is. Generally speaking, whole foods and minimally processed foods (vegetables, fruit, mushrooms, legumes, whole grains) and meals made from them are beneficial, while ultra processed food products and fast food are often a source of added sugars and carbohydrates with a high glycemic index. Many also contain low-quality fats and a large amount of sodium and additives.

Why is a diet with a high glycemic index harmful?

Foods with a high GI are less satiating and therefore lead more easily to overeating and obesity. At the same time, such a diet leads to a greater production of insulin, which puts pressure on the pancreas and leads to greater variability of blood sugar levels. In patients with diabetes, foods with a high GI cause a faster and steeper rise of blood sugar levels than the same amount of carbohydrates with a lower GI.

The unwanted effects of a diet with a high GI are multifold: