Glycemic index. Theory and practice of weight loss. How do high glycemic foods interfere with weight loss? What affects the glycemic index of foods

The glycemic index (GI) is a dietary indicator that reflects the effect of food consumed on the concentration of glucose in the blood. For the first time this concept was used in 1981 by University of Toronto professor David Jenkins, who set himself the task of developing an effective and safe diet for people with diabetes. A Canadian scientist considered it unconvincing that all foods containing sugars have the same effect on changes in blood glucose levels. In order to refute this theory, Jenkins conducted a whole range of experiments that made it possible to track the processes occurring in the body.

During the study, the subjects were asked to try various foods containing a fixed amount (50 g) of carbohydrates and take tests to determine the concentration of sugar in the blood. The results of these analyzes were compared with the indicators obtained in the study of the blood of a person who ate 50 g of pure glucose. The result of scientific work, which lasted more than 15 years, was the development of a conceptually new classification of products.

In accordance with this classification, carbohydrate-containing products are divided into three large groups:

• with high GI (from 70);
• with an average GI (more than 40, but less than 70);
• with low GI (not higher than 40).

This article will focus on foods with a low glycemic index and their impact on the processes occurring in the human body.

Benefits of Including Low GI Foods in Your Diet

Eating foods with a high glycemic index is accompanied by a sharp increase in the concentration of glucose in the blood and the active synthesis of a pancreatic hormone called insulin. Insulin contributes to the uniform distribution of sugars throughout all organs and tissues of the human body and their partial conversion into fats. In addition, the hormone produced by the pancreas protects the body's already existing body fat from being broken down and converted into energy. Thus, the regular inclusion in the diet of foods with a high glycemic index contributes to the accumulation of subcutaneous fat and systematic weight gain.

When eating low GI foods, the situation changes radically. Products belonging to this group are digested for a long time in the gastrointestinal tract and do not provoke a sharp increase in the concentration of sugar in the blood. The pancreas synthesizes insulin in small quantities, which means that the prerequisites for excessive accumulation of subcutaneous fat disappear. In other words, including low GI foods in your diet and avoiding high GI foods is one of the keys to weight loss. Along with this, following a diet based on eating foods with a low glycemic index has a beneficial effect on blood lipid profile and helps prevent the development of a number of cardiac diseases.

Low glycemic index food table

The list of foods with a low glycemic index includes:

• vegetables;
• pasta, for the preparation of which durum flour was used;
• most of the fruits and berries;
• raw oatmeal;
• greens;
• whole grains, whole grain bread;
• nuts;
• legumes;
• mushrooms, etc.

For more information on low GI foods, see the table below.

It is easy to see that the list does not include meat, fish, poultry and other protein products. This is explained by the fact that protein foods contain practically no carbohydrates, which means that its glycemic index tends to zero.

Factors affecting the glycemic index of foods

• One of the most important factors that can increase or decrease the glycemic index is the level of food processing. Refined foods (such as refined sugar or polished rice) and overcooked foods almost always have a higher GI. So, for example, the glycemic index of raw carrots is 34, and boiled - 86.
• Fibrous, tough foods that require a long digestion time, as well as foods high in fiber, almost always have a low glycemic index. For example, the GI of ripe fresh apples is 29, while the glycemic index of apple juice without pulp and sugar is 39.
• Foods rich in simple (fast) carbohydrates have a higher glycemic index compared to foods rich in complex (slow) carbohydrates.
• The more fat and protein components in a food, the lower its glycemic index. Fats and proteins slow down the digestion of starch found in consumed foods and increase the time it takes for them to be completely digested.
• Foods that contain resistant starch have a lower GI than foods rich in easily digestible starches.
• The riper vegetables or fruits, the higher their GI. So, for example, the glycemic index of slightly green, unripe bananas ranges from 29–45, while overripe bananas reach 80–90.
• In most cases, acidic food has a low GI: the acids present in its composition slow down the process of assimilation of starches. Conversely, salt added to meals accelerates the absorption of glucose and significantly increases the glycemic index of foods.
• Grinding foods during cooking contributes to their glycemic index. The digestion of crushed food takes less time, which means that the absorption of the sugars contained in it occurs much faster.
• The glycemic index of foods directly depends on what sugars are present in their composition. For example, meals containing glucose (glucose syrups, some juices, sports nutrition, etc.) dramatically increase blood sugar and have a high GI. At the same time, foods containing fructose (many fruits and berries) practically do not increase the sugar content in the blood, which means they have a low glycemic index.

(GI) - an indicator of the effect of carbohydrate-containing foods on the level of glucose (sugar) in the blood, stimulating the production of the insulin hormone of the pancreas. Differentiates products that provoke weight gain, controls the consumption and quality of carbohydrates. The GI is consistently taken into account in dietary plans for diabetes, coronary heart disease, obesity, or in healthy lifestyles and professional sports.

History of glycemic index research

The question of the effect of carbohydrate-containing products on glycemia (blood glucose level) was raised in the seventies of the twentieth century by Professor L. Krapo of Stanford University as part of a study of metabolic processes. The professor questioned the generally accepted postulate about the same insulin response of the body in response to the intake of different groups of carbohydrates and proved that the effect on glycemia of products with the same carbohydrate concentration is different.

The very concept of "glycemic index" was introduced only in 1981 by Professor D. Jenkins, who, based on the results of Crapo's research, developed a method for calculating the GI and classified foods according to this indicator into three groups:

• GI 10-40;
• GI 40-50;
• GI over 50.

The starting point for measuring the GI level was taken to be glucose values ​​equivalent to 100 units, which meant instant absorption and entry into the blood.

Relationship between GI, insulin production and weight gain

Insulin produced by the pancreas is responsible for the breakdown and processing of carbohydrates entering the body, energy processes, metabolism and transport of nutrients into cells. The glucose obtained as a result of the breakdown of carbohydrates is used for current energy needs and for replenishing glycogen stores in the muscles. The excess is not utilized, but enters the body's fat depots. The other side of insulin's work is blocking the reverse conversion of fat mass into glucose. Eating foods with a GI over 50 causes a persistent excess of glucose, the unnecessary reserves of which replenish the subcutaneous fat layer and provoke weight gain. A permanent excess of sugar in the blood gives a metabolic disorder.

Glycemic Index and Glycemic Load

When developing a diet and individual nutrition, focusing solely on GI indicators is erroneous for three reasons.

Reason #1. The GI value is correlated with the degree of maturity and the way the product is processed. The glycemic index for corn kernels is 70, and corn flakes, even without additional flavor enhancers, are equal to 88. The GI of a green unripe banana is 40, and a ripe fruit reaches a value of 65.

Reason number 2. In addition to the glycemic index, the value of the glycemic load (GL) is important, calculated by the formula: GI multiplied by the amount of carbohydrates contained in 100 g of the product divided by 100. With equal glycemic index values, the glycemic load of products differs. The GI of watermelon is 75, sweet fried cheesecakes - 76 units. The carbohydrate content is 6.8 for watermelon and 38.8 for cheesecakes. According to the above formula, the glycemic load of watermelon is 5.1, cheesecakes - 29.4. With a similar GI, the degree of usefulness of these products is not the same. The dynamics of the glycemic index is identical to the glycemic load. The lower the GN score, the higher the chances of maintaining weight within the normal range.

Reason number 3. There is no relationship between GI and calorie intake. A number of products with a GI below 50 calories and vice versa. For example: the glycemic index of olives, lentils and corn is 15, 25 and 70, but the calorie content of corn (123 kcal) is lower than that of olives (175 kcal) and lentils (327 kcal).

Glycemic index and diet

Proper nutrition, a healthy lifestyle, body weight control and a decrease in the percentage of fat content limits the consumption of foods with a glycemic index over 50. Food with a GI within the 10-40 group is preferred, and the intake of carbohydrates and carbohydrate-containing foods is transferred to the first half of the day. However, in this mode there are exceptions related to the schedule and intensity of training.

The intake of foods with a glycemic index level greater than 50 is acceptable before, during and after training and is regulated by a number of reasons.

Before training. Taking carbohydrates with a GI over 50 is appropriate before the serious energy expenditure associated with short, intense workouts. For nutrition before prolonged physical exertion, choose foods with a glycemic index in the range of 10-40.

During a workout. The systematic use of foods with a GI level of up to 40 provokes the occurrence of a state of hypoglycemia (a drop in blood sugar), accompanied by disability, trembling, cold sweat and chills. Loss of strength is also possible during training. In this case, it is necessary to take fast-digesting carbohydrates in soluble form with a GI exceeding 50, instantly absorbed by the body (as an option - taking glucose).

After workout. During this period, replenishment of wasted energy is required, so the immediate intake of carbohydrates with a glycemic index of more than 50 after training is necessary. The production of insulin provoked by such products gives an anti-catabolic effect and prevents the destruction of muscle proteins. An hour after leaving the gym, the body will need products with an average glycemic index or with a GI below 40.

Instructions for use

The glycemic index is a value recommended for taking into account in order to maintain weight indicators or reduce body weight. However, it is necessary to evaluate the diet from the position of a total understanding of the glycemic index, glycemic load, calorie content of the product and the percentage of proteins, fats and carbohydrates.

Food glycemic index table

The glycemic index is an important characteristic of a carbohydrate product, showing how quickly and how high blood sugar levels rise after eating this product. The glycemic index (GI) ranges from 0 to 100, where 100 is a kind of standard that reflects the effect of pure glucose on blood sugar levels.

According to the GI ratio, foods are most often divided into three groups: low, medium and high glycemic index. Previously, before detailed studies, it was believed that complex carbohydrates slowly increase blood sugar levels by default, while simple carbohydrates, on the contrary, are responsible for insulin spikes. Studies have shown that among the foods with a high glycemic index there are very unexpected names - including complex carbohydrates.

Foods with a high glycemic index (70-110). Mostly foods with a high glycemic index are simple carbohydrates, which are not considered useful or beneficial to the figure by any dietary food system. Among the "champions" in GI, you can see the following products: beer (110), white bread and pastries (100), potatoes (90), chips (85), dumplings (70), sugar and chocolate (70). But there are also surprises. Some foods approved by nutritionists and included in various diets also have the highest glycemic index. For example, honey (90), dates (103), muesli (80), etc. In addition, some vegetables and fruits also cannot boast of the ability to normalize blood sugar levels. These are swede (99), carrots (85), watermelon, zucchini and pumpkin (all - 75). By the way, the high GI (75) of watermelon alone can debunk the myth about the benefits of the so-called “watermelon diet”, which can only lead to an excess of easily digestible carbohydrate and wild jumps in blood sugar levels.

Foods with an average glycemic index (55-70). Occupy an intermediate position; They are well absorbed and saturate well, but still quite quickly give way to a feeling of hunger, cause a rapid increase in blood sugar levels. Medium GI foods are predominantly "satiating" carbohydrates and nutritious fruits. The most notable representatives of the group of products with an average GI are unleavened pastries (70), semolina porridge (65), instant oatmeal (66), black bread (65), pasta and pancakes (60), pizza (60), rice ( 60). Including vegetables and fruits: pineapple (66), bananas and melons (65), raisins (65), beets (64), sweet corn (64), papaya (60).

Foods with a low glycemic index (1-55). These products are the most "long-playing" source of energy for the body. They are slowly absorbed, broken down, give a long-term feeling of fullness, raise blood sugar levels slowly and slightly. This group of products includes the vast majority of fruits and vegetables: lettuce, cabbage, onions, tomatoes, eggplants (all 10 each), apricots (15), apples and peaches (30), oranges and grapefruits (35), kiwi (50) , mango (55), etc. The next impressive representative of the low GI food group is whole grains: pearl barley (22), legumes (30), maize (35), rye, wheat and buckwheat grain bread (40), oatmeal, brown rice, buckwheat (all - 50 ). Other low-GI foods include some dairy products: whole milk (30), low-fat yogurt (40), sweet yogurt and ice cream (45); nuts and seeds: sunflower seeds (10), walnuts (15), peanuts (20); mushrooms (10); fruit juices without sugar (about 50); bran (up to 50) and even oatmeal cookies (55).

Do I need to consider the GI of foods when losing weight?

Also exists the relationship between the glycemic index of the consumed product and subsequent eating behavior. If you eat a low GI food for breakfast, for example, you will feel full longer than if you eat a high GI food. You will want to eat after such a breakfast much later and you will also eat less for lunch. In addition, eating foods with a low glycemic index has a beneficial effect on metabolism and digestion.

Each product contains a different nutritional value. It would be foolish to believe that the food intake is always the same content of proteins, carbohydrates and fats, which form the overall picture of the energy value of food.

Due to different indicators of nutrients, the calorie content of the dish also changes. Currently, many who want to lose weight or, conversely, gain weight, look at this particular unit, but with proper nutrition, it is important to take into account one more indicator - the glycemic index of foods. For the body, it also plays an important role and helps with many diseases, such as diabetes. So, what is the glycemic index and what function does it perform for a person?

What is the glycemic index of foods?

The glycemic index of foods (GI) is unit of the rate at which glucose rises in the body after eating a particular food. To fully understand this definition, we can characterize this process. Carbohydrates are the most important energy value. They can be complex and determined by the number of intermolecular bonds (polysaccharides) and simple (disaccharides, monosaccharides). When complex carbohydrates and other nutrients enter the body, under the influence of enzymes, splitting into simple ones occurs, and simple ones under the influence of chemical reactions to glucose.

The faster the breakdown rate, the more glucose is formed and the blood sugar level rises. This is a high glycemic index food. At a low speed, cleavage products are retained for a long time and absorbed more slowly. This gives a feeling of fullness for quite a long time. and for weight loss, as well as people suffering from diabetes, this low index will be the most optimal.

The concept of the glycemic index was introduced in 1981 at the Canadian University of Toronto by the scientific doctor David Jenkins. For this, special experiments were carried out, during which volunteers were given food products containing carbohydrates in the amount of 50 g. Then, for an hour, every 15 minutes, a blood test was taken and the level of sugar in the blood was determined. Based on the data obtained, special graphs were built, and the experiments continued. When it was possible to obtain all the necessary data, the very concept and definition were introduced. However, this value is a relatively relative unit, the essence of which is to compare products with pure glucose, which has a 100% glycemic index.

When the question arises, what is the difference between the concept of "caloric content" and "glycemic index", the answer is as follows. GI is a display of the rate of breakdown of carbohydrates into glucose and the degree of increase in blood sugar, and caloric content is only the amount of energy received from food intake.

Glycemic index table

In order to have an idea about the rate of carbohydrate breakdown in a particular dish, a special table has been created, where each product has its own glycemic index value. It was created to provide information specifically for each food product, at what rate the body breaks down its carbohydrates into glucose.

These data are important for people who adhere to a proper balanced diet, as well as those suffering from diabetes. According to established data, tables with GI have an approximate value, and the indicators themselves refer to one specific product without any heat or mechanical processing in one piece. There are 3 groups of food glycemic index:

• low (from 0 to 40);
• medium (from 40-70);
• high (from 70 and more).

The table does not include fat-free cheeses and dairy products, broths, and water. This is due, first of all, to the fact that their glycemic index is almost zero.

Low GI

Average GI

high GI

What determines the glycemic index of foods?

Not always the use of products occurs one by one and fresh. When cooking and with other mechanical effects on products, the level of absorption of carbohydrates changes. So, for what reasons does the glycemic index of foods change in the finished dish:

1. Adding flavored additives and sugar to food increases the GI.
2. total fiber content. Fibers have the ability to slow down digestion and the entry of glucose into the circulatory system.
3. Product processing method. Structured foods that require a lot of chewing have a lower GI, for example, raw vegetables in this case are better than boiled. Products subjected to mechanical or heat treatment increase the index.
4. Fruits and vegetables of greater ripeness increase the GI.
5. An important indicator is the method of cooking. Grain bread will have a lower GI value than cooked puffed wheat bread.
6. The more food is crushed during cooking, the more the glycemic index increases. For example, the GI of a peach will be lower when consumed whole than when consumed as peach juice.

However, in addition to these factors, the individual characteristics of the human body are also taken into account. The response to the intake of foods with a low or high GI may depend on:

• age;
• ecology where a person lives;
• metabolic states;
• the state of the immune system;
• the presence of infectious or inflammatory diseases in the body;
• from medications taken that can affect the rate of protein breakdown;
• on the amount of physical activity.

With the gradual introduction of foods with low or medium GI into your habitual diet, you can edit and arrange your usual foods for better digestibility, based on your personal characteristics of the body.

What is glucose for?

In the body, glucose plays an important role and provides almost half of the energy consumption of the entire body. The functional feature of glucose is its maintenance of normal brain function and the functioning of the nervous system. In addition, it is a source of nutrition for tissues and the muscle layer, and is involved in the formation of glycogen.

Glycemic index and diabetes

Diabetes mellitus is a disease in which the control of blood sugar levels is impaired. If in a healthy person, when taking foods with a high GI, excess glucose is distributed into body fat, and the sugar level returns to normal, then in a sick person with diabetes, there are certain problems. At the time of eating with a high GI, the normal allowable blood sugar level is exceeded due to a violation of insulin secretion or sensitivity of cell receptors. In another way, you can say this:

• 1 type of diabetes. Insulin is not produced, and if this does not happen, then there is no blockage of the increase in blood sugar, and as a result, hyperglycemia is observed, which is dangerous for the development of hyperglycemic coma.
• Type 2 diabetes. Insulin is produced, but there is no sensitivity of cell receptors. Therefore, at the time of the breakdown of food to glucose, insulin carries it to cells that do not respond to its effects, and if this does not happen, then sugar remains in the circulatory system, hyperglycemia develops.

Patients with diabetes simply need to adhere to a proper balanced diet. The glycemic index of foods is especially important for this population group. After all, it is a kind of guideline, on which it depends on how quickly this or that product will be split and whether there will be a jump in sugar levels. Indeed, for comparison, when a healthy person eats low-GI foods in his body, the sugar level remains within the normal range, and if a diabetic does the same, the sugar in his blood rises slightly. Therefore, when compiling a menu for every day, it is worth calculating the calorie content of each dish, looking at the GI table and not endangering your health.

GI during weight loss

With a quick weight loss, kilograms return at lightning speed back. For more than a decade, it has been said that in order to lose weight, you must adhere to proper nutrition. And if it was obvious to everyone just to calculate the calorie content of a dish, then you can also add the glycemic index of products to this widespread activity. So what is it good for weight loss?

Firstly, this is a kind of systematic folders. What you can eat and what is healthy, and what you should refrain from and, in principle, it is not so necessary. For those who want to lose weight, it is best to pay attention to the table with a low glycemic index of products; you can look at products with average indicators as much as possible. But to use products where the index has a high value is not worth it. Everything must be balanced, and with the help of an index, tracking portions and product characteristics is much more convenient than counting the calorie content of each dish.

Secondly, when eating foods with a high GI, the feeling of fullness can come after eating more than you need. Unused glucose, in this case, will be deposited in the fatty layer. This will not happen from eating low GI foods: glucose levels will rise smoothly, satisfying the energy needs of a person.

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Genus. 1984 Trained since 1999. Trained since 2007. CCM in powerlifting. Champion of Russia and the South of Russia according to AWPC. Champion of the Krasnodar Territory according to IPF. 1st category in weightlifting. 2-time winner of the championship of the Krasnodar Territory in t / a. Author of over 700 articles on fitness and amateur athleticism. Author and co-author of 5 books.

The glycemic index is a measure of the effect of foods on the level of sugar (glucose) in the blood after eating them.

That is, the higher it is, the faster the blood sugar rises after eating certain foods. Glucose was taken as the standard. Its glycemic index is 100. The glycemic index of buckwheat porridge is 50. This means that the level of sugar, after you have eaten buckwheat porridge, rises 2 times slower (and 2 times lower) than from glucose. Let's go further. And what determines the rate of increase in sugar levels? For the most part, it depends on the rate of splitting (digestion) of a particular product. There are, of course, other factors that affect this, but the speed of digestion is the main one. Therefore, we can say that:

The glycemic index is a measure of how quickly foods are absorbed (digested) in your body. Higher index - faster digestion. Below is slower.

I repeat once again that such a definition is more rough and exaggerated, but easier to understand the essence. Better to get the gist but not the nuances than to get nothing at all. By the way, as many have probably guessed, only those foods that contain carbohydrates have a glycemic index. Since glucose is obtained only from the breakdown of carbohydrates. That is, if you eat a product without carbohydrates at all, then your sugar level will remain the same.

How does the glycemic index affect weight loss?

When is the best time to eat high GI foods?

• Immediately after training.
• Right after sleep.

What foods have a high GI?