- Gross and net energy value
- Energy value - food with the highest energy value
- Energy value - food with the lowest energy value
- Energy value - how to calculate the calorific value of food?
- Is a calorie always a calorie?
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The energy value of a food is the information that can be found on its packaging, usually in a nutritional table. The calorific value of a meal or a daily diet is calculated by summing up the energy values of individual food products that make up the meal. See how to calculate the energy value of a meal.
The energy valueof food in physical terms is the heat that is released as a result of "burning" or oxidizing food ingredients. The amount of released heat depends on the content of carbon, hydrogen, nitrogen and sulfur atoms in the food and their ratio to the number of oxygen atoms. In practice, we use the experimentally determined calorific value of proteins, carbohydrates and fats.
Knowing their content in a product, we calculate its energy value. If a product contains a lot of water in relation to other ingredients, the caloric content decreases. When it is high in fat, it grows.The energy value offood also depends on the fiber content, which reduces it, and on the technological processing, which increases the digestibility of the meal, so it increases its calorific value.
When determining the energy value, not only the composition of the products (protein, fat, carbohydrate and fiber content) is very important, but also their digestibility. Only digested food becomes a source of energy for the body.
Energy is a physical quantity that can be measured and its value is expressed in various units. One such unit that we have been using for over 130 years is the calorie, now referring to the energy contained in food.
Worth knowingThe energy value of a food (also known as the calorific value of food) is the amount of energy that the body can absorb as a result of digesting food. It is expressed in kilocalories (kcal) corresponding to 1000 calories (cal) or in kilojoules (kJ). 1 kilocalorie (kcal) is equivalent to 4.18 kilojoules (kJ).
1 kcal=4.184 kJ
Gross and net energy value
Atwater's research led to the concepts of "gross energy" and "net energy". Gross energy is the amount of heat released by food when it is completely burned in a calorimetric bomb, outside the living organism. It is higher than the actual energysecreted during digestion, because the body is unable to digest ("burn", oxidize) all organic compounds completely.
Urea is excreted in the urine, partially reducing the gross energy value. In addition, energy is used for digestion as well, which affects the net energy value. Net energy is the heat that is released in the body during the digestion of food (catabolic transformations=decay) and can be used just as heat or converted into ATP (adenosine triphosphate, a high-energy compound that is an energy carrier for the body cells).
Based on research in a calorimetric bomb, it was determined that the gross energy of burning 1 g of nutrients is:
- protein - 5.65 kcal
- fat - 9.45 kcal
- carbohydrates - 4.15 kcal
Then, the physiological energy equivalents were determined, taking into account the metabolic changes actually taking place during digestion in the body. Establish a human nutrient digestibility factor:
- protein - 92%
- fat - 95%
- carbohydrates - 98%
It was also estimated that as a result of the consumption of 1 g of protein with urine, 1.25 - 1.3 kcal is excreted in the form of nitrogen compounds. In this way, the net energy from nutrient consumption was calculated, which is:
- 1 g of protein - (5.65 - 1.3)0.92=4.0 kcal
- 1 g fat - 9.450.95=8.98 kcal
- 1 g carbohydrate - 4.10.98=4.0 kcal
Energy value of nutrients
The nutrients are currently assumed to provide the following amounts of energy:
- 1 g protein=4 kcal=17 kJ
- 1 g fat=9 kcal=37 kJ
- 1 g carbohydrate=4 kcal=17 kJ
- 1 g of alcohol=7 kcal=29 kJ
- 1 g of fiber=2 kcal=8 kJ
- 1 g of polyols, e.g. xylitol=2.4 kcal=10 kJ
- 1 g of organic acids=3 kcal=13 kJ
- 1 g of erythritol=0 kcal=0 kJ
Energy value - food with the highest energy value
Foods with a high fat content have the greatest energy value. We present a short list of food products with the highest calorific value per 100 g.
| Food item | kcal in 100 g |
| Olive oil, rapeseed oil and other vegetable oils without additives | 884 |
| Butter | 735 |
| Macadamia nuts (other nuts similar, approx. 650 kcal) | 718 |
| Mayonnaise | 711 |
| Coconut shrims | 698 |
| Peanut butter | 695 |
| Sesame | 673 |
| Chocolate eggs with filling | 666 |
| Lard | 651 |
The list of the most caloric foods includes oils, butter, margarines, spreads, etc. Next, nuts, and then seeds. The vast majority of these are sweets from the store: cookies, wafers, bars, chocolate covered nuts, stuffed candies, chocolates, etc., as well as chips.
| Chocolate 86% | 645 |
| Raffaello | 628 |
| Pork Kabanos | 611 |
| Chocolate 70% | 599 |
| Chocolate covered almonds | 597 |
| Pumpkin seeds, sunflower seeds | ok. 580 |
| Baked bacon | 548 |
| Nutella | 546 |
| Peanuts with wasabi coating | 537 |
| Chipsy | 535 |
| Millet cakes with linseed | 526 |
Author: Time S.A
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Energy value - food with the lowest energy value
| Product | kcal in 100 g |
| Water, tea | 0 |
| Light drinks | 0 |
| Stevia, erythritol | 0 |
| Black coffee | 2 |
| Pickled cucumbers | 11 |
| Pak choi | 13 |
| Fresh cucumber | 14 |
| Lettuce | 14 |
| Tomato juice | 14 |
There is no doubt that vegetables are the foods with the lowest energy value. Raw vegetables and their preserves (soups, salads, etc.) prepared only with the addition of spices occupy the first few hundred places on the list of foods with the lowest calorie content. This is due to their composition - vegetables are mainly water and fiber. This list only includes beverages sweetened with sweeteners, tea, coffee and calorie-free sweeteners.
| Whiteradish | 14 |
| Rhubarb | 15 |
| Sauerkraut | 16 |
| Red semi-sweet non-alcoholic wine | 16 |
| Ribbed celery | 17 |
| Zucchini | 17 |
| Kubuś Waterrr | 18 |
| Pure red borscht | 18 |
| Tomato | 19 |
| Alcohol-free beer | 21 |
Low-energy products (up to 50 kcal in 100 g) include low-sweet fruits, e.g. cherries, strawberries, currants, wild strawberries, watermelon, grapefruit, papaya, raspberries, gooseberries, plums, apples, peaches. About 100 kcal in 100 g have white fish, seafood, skinless lean poultry meat, lean cottage cheese.
Energy value - how to calculate the calorific value of food?
The energy value, i.e. the calorific value of a food product or a whole meal, can be calculated without any problems, only knowing the content of macronutrients - protein, fat, carbohydrates and fiber. How to do it step by step? Here is an example for a single product and a whole meal made up of several components. [In the calculations, the division by 1 g or 1 kcal, which shows the correctness of the obtained unit, was omitted. However, the division was always done according to the same pattern, for example:
- 1 g - 4 kcal
- 16 g - x kcal
- 1 gx kcal=16 g4 kcal
- x kcal=16 g4 kcal / 1 g
- 1 kcal - 4.18 kJ
- 75.3 kcal - x kJ
- 1 kcalx kJ=75.3 kcal4.18 kJ
- x kJ=75.3 kcal4.18 kJ / 1 kcal]
Pear weighing 130 g
| Macronutrient content | Calorific value of macronutrients | Energy value of the product | Energy value in 100 g |
| Protein=0.8 g | 0.8 g4 kcal=3.2 kcal | 75.3 kcal | 75.3 kcal100 g / 130 g=57.9 kcal |
| Fat=0.3 g | 0.3 g9 kcal=2.7 kcal | 75.3 kcal4.18 kJ=314.75 kJ | 57.9 kcal4.18 kJ=242 kJ |
| Carbohydrates=16 g | 16 g4 kcal=64 kcal | ||
| fiber=2.7 g | 2.7 g2 kcal=5.4 kcal |
Cocoa cocktail with banana on coconut milk. Ingredients:
- Coconut Milk 80% (200 g)
| Macronutrient content | Calorific value of macronutrients | Energy value of the product |
| Protein=4.2 g | 4.2 g4 kcal=16.8 kcal | 405.6 kcal |
| Fat=36 g | 36 g9 kcal=324 kcal | 405.6 kcal4.18 kJ=1695.4 kJ |
| Carbohydrates=16.2 g | 16.2 g4 kcal=64.8 kcal | |
| Fiber - 0 g | 0 kcal |
Banana (120 g)
| Macronutrient content | Calorific value of macronutrients | Energy value of the product |
| Protein=1.2 g | 4.2 g4 kcal=16.8 kcal | 117.2 kcal |
| Carbohydrates=26.2 g | 36 g9 kcal=324 kcal | 117.2 kcal4.18 kJ=489.9 kJ |
| Carbohydrates=16.2 g | 16.2 g4 kcal=64.8 kcal | |
| fiber=2 g | 2 g2 kcal=4 kcal |
Cocoa (10 g - spoon)
| Macronutrient content | Calorific value of macronutrients | Energy value of the product |
| Protein=1.8 g | 1.8 g4 kcal=7.2 kcal | 48.6 kcal |
| Fat=2.2g | 2.2 g9 kcal=19.8 kcal | 48.6 kcal4.18 kJ=203.2 kJ |
| Carbs=5.1 g | 5.1 g4 kcal=20.4 kcal | |
| Fiber=0.6 g | 0.6 g2 kcal=1.2 kcal |
Chia seeds (10 g - tablespoon)
| Macronutrient content | Calorific value of macronutrients | Energy value of the product |
| Protein=1.7 g | 1.7 g4 kcal=6.8 kcal | 44.7 kcal |
| Fat=3.1g | 3.1 g9 kcal=27.9 kcal | 44.7 kcal4.18 kJ=186.9 kJ |
| Carbohydrates=0.8 g | 0.8 g4 kcal=3.2 kcal | |
| fiber=3.4 g | 3.4 g2 kcal=6.8 kcal |
Honey (12 g - teaspoon)
| Macronutrient content | Calorific value of macronutrients | Energy value of the product |
| Protein=0 g | 0 kcal | 38 kcal |
| Fat=0 g | 0 kcal | 38 kcal4.18 kJ=158.9 kJ |
| Carbs=9.5 g | 9.5 g4 kcal=38 kcal | |
| fiber=0 g | 0 kcal |
The energy value of the whole meal is 654.1 kcal=2734.1 kJ
Weight of the whole meal=200 g + 120 g + 10 g + 10 g + 12g=352 g
The energy value of a 100 g meal is 100 g654.1 kcal / 352 g=185.8 kcal (185.8 kcal=776.6 kJ)
Is a calorie always a calorie?
Many scientists with the traditional approach are implacable and claim that calories are calories, they always provide the same amount of energy, always contribute to weight control in the same way, and only the amount of calories consumed is responsible for gaining or losing weight. However, it must be remembered that the human body is not a steam engine or other mechanical device.
There is nothing "for sure" about it. A breakthrough in changing the mathematical approach to weight control was the research of Dr. David Ludwig, who in his experiments used different types of diets (e.g. high-protein, high-fat, high-carbohydrate) with the same caloric content. He found that different types of diets affect body weight differently. Such conclusions can be found in numerous scientific publications, which most often show that high-fat diets are much more effective in slimming than low-fat diets with the same calorific value.
Opponents of calorie counting emphasize that the real energy value does not only result from the amount of energy that is released from food, but also from the time it takes for food to travel through the digestive tract and the energy expenditure needed for digestion. High-carbohydrate, low-fat diets consist of foods that are digested very quickly and require little energy to break down. In contrast, high-fat foods pass through the digestive tract more slowly, and digesting them is a process that consumes a lot of energy.
From this the conclusion is that the energy effect after eating a carbohydrate and fat or protein meal is different for the body. The absorption time of food affects body weight. So the energy value of a meal is not just simple math based on protein, fat, carbohydrate and fiber content. The energy value of individual foods may be different for each person, and it depends on his predisposition, secretion of digestive enzymes, hormones and many other factors.
Worth knowingThe concept of "calorie" was introduced to the world of science by the nineteenth-century French scientist Nicolas Clement-Desormes, who was interested in steam engines. He was looking for an adequate index of thermal energy measurement in these machines. The value of one calorie was assigned to the amount of energy needed to heat 1 gram of chemically pure water by 1oC, more precisely from the temperature of 14.5oC to 15.5oC. The name of the unit "calorie" comes from the Latin "calor" or heat.
Clement's researchwas used in the 1880s by the American amateur nutritionist Wilburg O. Atwater in his quest to find out which foods provided the most energy. He constructed a device called the calorimetric bomb, which is still used today to determine the calorific value of food products. The calorimetric bomb is a small furnace surrounded by a water cover. The products are completely burned in it and the released heat is measured.
In the science of nutrition, the colloquial term "calorie" means "kilocalorie", that is the amount of heat needed to raise the temperature of 1 liter of water by 1oC. Atwater burned dozens of foods in his device, which led him to conclusions about the calorific value of food in dietary studies to this day.
Sources: 1. Dr. M. Schlegel - Zawadzka, Bromatologia - lecture, http://www2.chemia.uj.edu.pl/dydaktyka/bromatologia/bromatologia2.pdf 2. Tobias D.K. et al., Effect of low-fat diet interventions versus other diet interventions on long-term weight change in adults: a systematic review and meta-analysis, The Lancet, Diabetes & Endocrinology, 2015, 3 (12), 969-979 3 Ebbeling C.B. et al., Effects of dietary composition on energy expenditure during weight-loss maintenance, JAMA, 2012, 307 (24), 2627-2634 4. Bujko J., How is the caloric content of food products measured, Świat Nauki, https: // www.swiatnauki.pl/8,724.html 5. www.ilewazy.pl
About the author
Aleksandra Żyłowska-Mharrab, dietician Food technologist, dietitian, educator. A graduate of Biotechnology at the Gdańsk University of Technology and Nutritional Services at the Maritime University. A supporter of simple, he althy cuisine and conscious choices in everyday nutrition. My main interests include building permanent changes in eating habits and individually composing a diet according to the body's needs. Because the same thing is not he althy for everyone! I believe that nutritional education is very important, both for children and adults. I focus my activities on spreading knowledge about nutrition, analyze new research results, and make my own conclusions. I adhere to the principle that a diet is a lifestyle, not strict adherence to meals on a sheet of paper. There is always room for delicious pleasures in he althy and conscious eating.