The caloric value of natural food varies greatly, from about 41.8 ～ 125.6 kJ / 100 g of leafy vegetables (such as ball lettuce, oil wheat and so on) to about 1339.5 ～ 1590.6 kJ / 100 g of grain and starch beans, and then to 2092.9 ~ 2930.1 kJ / 100 g of nuts (the highest are macadamia nuts and pine nuts).
How to judge the calorie value of food simply? There are several basic rules:
1. The greater the water content in food, the lower the caloric value. Conversely, the more dry goods, the higher the calorific value
Compared with different vegetables, vegetables with high water content have the lowest calories, such as winter melon, cucumber, lettuce, etc., “water and water”, calories are only 41.8 ~ 83.7 kJ / 100 g level. In contrast, although sweet pea and beans are also considered high-moisture foods, they have a little more “dry goods” and the calories are 125.6-209.3 kJ / 100 g. Potatoes, yam and the like that contain starch have higher calories, reaching 251.2 to 334.9 kJ / 100 g.
Vegetables turn into dried vegetables, fruits turn into dried fruits, sweet potatoes turn into dried potatoes, beef turn into dried beef … there is less water and more dry goods, the caloric value will increase several times. The reason is very simple, only a few pounds of fruits and vegetables can be made into a pound of dried fruits and vegetables! The heat is of course concentrated.
For example, cooking 1 bowl of rice with water to make 3 bowls of rice porridge, although the volume is large, but the total calories have not changed, so the caloric density is small. Conversely, if you turn sweet potatoes into dried sweet potatoes, there will be less water and more dry goods, and the caloric density will be greater, so you will eat more calories if you are not careful. If someone asks me how many calories a bowl of porridge contains, I certainly ca n’t answer. Because if he does n’t tell me how much rice is put in the porridge and how much water is added, I ca n’t calculate how much dry rice, how much starch, how much protein, how many kilocalories it contains.
Here’s a hint: As long as you choose foods with the same amount of water, less dry goods, and less “oil and water” among similar foods, you don’t need to worry even if you eat more.
To be precise, eat more of these foods, and other high-calorie foods often have no appetite to eat, so it is not easy to gain weight. This is the so-called “more eating, less fat”.
2. For foods such as fruits, vegetables, juices, and sweet drinks, the higher the carbohydrate, the higher the calories
This type of food is usually low in fat (except for durian and avocado), and low in protein. Their main calorie source is carbohydrates (including sugar and starch), especially sugar. Sugar is a solute, the more sugar, the lower the proportion of water in the fruit or beverage.
Therefore, for the same fruit, the sweeter varieties have higher calories than the unsweetened varieties. For example, grapes are particularly sweet and can even reach sugar levels above 20%. 100% grape juice products are generally more than 15% sugar. For the same reason, looking at the calorie level of a sweet drink, just look at the nutritional composition table on its packaging. You will find that the amount of calories is directly proportional to the content of “carbohydrates”, and starch is generally not added to beverages, so carbohydrates are almost equal to sugar.
3. When the total amount of dry goods is similar, the higher the fat content, the higher the caloric value
Because the calories of 1 g of protein and starch / sugar are 16.7 kJ, and 1 g of fat is 9 kcal, so when the quantity of dry goods is roughly equal, the larger the proportion of fat, the higher the caloric value. For example, for the same whole plant seeds with very low water content, the calories of adzuki beans are 1356.2 kJ / 100 g, soybeans are 1632.5 kJ / 100 g, and raw peanuts are 2402.7 kJ / 100 g. Because the fat content of the three of them is 0.6%, 16% and 44%. Although the red adzuki bean starch content is as high as 63%, and the soybean protein content is as high as 36%, which is much higher than peanuts, but the peanut fat is high in terms of killing two kinds of beans.
In the same way, when making dishes, the ingredients are unchanged, the more cooking oil added in the cooking, the more fat is inhaled, and the higher the calorie value of the dishes.
4. In the case of the same high calorie value, the higher the digestion and absorption rate, the higher the calories
Dietary fiber in food will delay the speed of digestion and absorption, and resistant starch is not easy to digest and absorb. However, resistant starch is often included in the caloric value of food. The so-called resistant starch means that although it is pure starch, it is difficult to be digested by people in the small intestine. They will enter the large intestine directly, as fermentable dietary fiber, become the “food” of beneficial bacteria in the large intestine, and produce “short-chain fatty acids”. These short-chain fatty acids help to inhibit harmful bacteria, help prevent bowel cancer, and help control blood lipid levels.
Natural whole grains, starch, beans, and potatoes all have a part of “resistant starch”. However, after refined processing, the dietary fiber is removed, the digestion and absorption rate is usually very high, such as rice buns, biscuit bread, puffed food and the like.
In addition, dietary fiber can carry a small amount of fat into the large intestine and eventually be excreted. The polyphenols in food can also help a small amount of starch, protein and fat enter the large intestine by reducing the activity of digestive enzymes, and escape the fate of being digested and absorbed by the human body.
Natural food needs to be chewed. When it is not crumbly enough, the digestion and absorption rate will be slightly lower. For example, nuts with a very hard texture, such as almonds and almonds, cannot be completely chewed, and the digestion and absorption rate will be reduced accordingly. Studies have shown that the actual heat absorbed by the body is not as high as the calculated heat.
Here, we have to remember a concept: energy density.
Energy density is also called heat density. Refers to how much energy (calories) is contained in a unit of mass or volume of food. Since water and dietary fiber do not contain calories, foods with high water content and high fiber content have low energy density, such as vegetables and fruits. As compared by quality, the calorie of fat is the largest of the three energy-supplying nutrients. Therefore, in foods with the same moisture content, the more fat, the higher the calorie. Foods with low water content, high dry goods, and high fat content have the highest caloric value. Such food, if the nutrient content is low, it is very unfavorable for preventing obesity. Such as biscuits, cookies, potato chips, etc., are not worth eating often.
For specific food calorie values, please refer to the “Chinese Food Composition Table”. As for the caloric value of various commercially-processed branded foods, it is even simpler. Look directly at the “nutrient composition table” on the package. The mandatory mandatory items are: total energy (calories), protein, fat, carbohydrate and sodium content.
It should be noted that because China follows the “International Standard Unit” system, the calorific value on the labeled nutritional composition table is expressed in kilojoules (kJ). 1 kJ = 4.18 kilocalories. The calories of food calories are basically integers, but kilojoules have a lot of fractions, so it has to be converted when used, which is very troublesome. However, the operation is not so complicated, and the comparison between similar foods is done in kilojoules.
For example, one yogurt contains 530 kJ calories in 100 g, which is much higher than another containing 280 kJ calories … See if their protein content is similar, then buy 280 kJ directly.
Understand the basic knowledge of these food calories, and then look at the food composition table, you will lose a lot of confusion about food calories, and you will know when you eat later.