Calorie (Cal for short), transliterated from English Calorie, is defined as the heat required to raise 1 gram of water to 1 degree Celsius at 1 atmospheric pressure; Calorie is an energy unit, which is still widely used in nutrition measurement and fitness. The international standard unit of energy is joule.
As the legal unit of food calories, joules are widely used in Europe, while calories are used in the United States. Although Joule is the legal unit in Chinese mainland and Taiwan Province Province, it is still widely used in Chinese mainland and Taiwan Province Province because of tradition.
The calories a normal person needs every day are related to his weight. The relationship between calorie intake per hour and body weight is about 1 kcal/hour/kg, that is, 4. 186 kj/hour/kg. Therefore, the normal average daily calories required by an adult weighing 50 kg are as follows:
Average required heat? =4. 186 kJ？ *24 hours * 50kg = 5023.2kJ
Extended data:
How to judge the level of food calories
1. The greater the moisture content in food, the lower the calorie value. Conversely, the more dry goods, the higher the calorie value.
For example, compared with different vegetables, vegetables with high moisture content have the lowest calories, such as wax gourd, cucumber and lettuce. , "moist", and the heat is only 10~20 kcal/100g. In comparison, although sweet peas, beans and so on. It is also considered as a high-moisture food, with a little more "dry food" and a calorie of 30~50 kcal/100g. Starch-containing potatoes and yams have higher calories, reaching the level of 60-80 kcal/100g.
Vegetables become dried vegetables, fruits become dried fruits, sweet potatoes become dried sweet potatoes, and beef becomes dried beef. Less moisture, more dry goods, and the heat value will rise several times. The reason is very simple, a few jins of fruits and vegetables can be made into a catty of dried fruits and vegetables! Of course, heat is concentrated.
2. For fruits, vegetables, fruit juice, sweet drinks and other foods, the higher the carbohydrate, the higher the calorie.
This kind of food is usually low in fat (except durian and avocado) and low in protein. Their main source of heat is carbohydrates (including sugar and starch), especially sugar. Sugar is a solute. The more sugar, the lower the proportion of water in fruit or drink.
Therefore, the same kind of fruit, sweet varieties have higher calories than non-sweet varieties. Grapes, for example, are especially sweet, and the sugar content can even reach more than 20%. 100% grape juice products are generally more than 15% sugar.
By the same token, the calorie level of sweet drinks can only be judged by the nutritional composition table on its packaging. You will find that the level of calories is directly proportional to the content of "carbohydrates", and there is generally no starch in drinks, so carbohydrates are almost equal to sugar.
3. When the total amount of dry goods is almost the same, the higher the fat content, the higher the calorie value.
Because the calories of 1g protein and starch/sugar are 4 kilocalories, while the calories of 1g fat are 9 kilocalories, the higher the fat ratio, the higher the calorie value.
For example, the energy of intact plant seeds with low water content is 324 kcal/100g for adzuki beans, 390 for soybeans and 574 for raw peanuts. Because their fat content is 0.6%, 16% and 44% respectively. Although the starch content of adzuki bean is as high as 63% and the protein content of soybean is as high as 36%, which is much higher than that of peanut, the high fat content of peanut kills two kinds of beans.
4. The higher the digestion and absorption rate, the higher the calorie.
Dietary fiber in food will slow down digestion and absorption, and resistant starch is not easy to digest and absorb. However, resistant starch is often included in the calorie value of food.
The so-called resistant starch is the part of starch that is difficult to be digested in the small intestine, although it is pure starch. They will directly enter the large intestine, act as fermentable dietary fiber, become "food" for beneficial bacteria in the large intestine, and produce "short-chain fatty acids". These short-chain fatty acids are beneficial to inhibit harmful bacteria, prevent intestinal cancer and control blood lipid levels.
So remember a concept: energy density.
Energy density: Also called thermal density. Refers to how much energy (heat) is contained in food per unit weight or volume.
Because water and dietary fiber do not contain calories, foods with high water content and fiber content have low energy density, such as vegetables and fruits.
Baidu Encyclopedia-Calories (Calories Unit)
People's health network-four ways to easily judge the calorie level of food.