Calorie (cal) is a physical energy unit, which is widely used in nutrition measurement and fitness manual. This word is transliterated from English calories and is defined as the heat required to raise 1 degree Celsius at 1 atmospheric pressure (10 1.325kPa).

Most of us associate calories with what we eat or drink, such as "This soda contains 200 calories". In fact, the calories listed on food packaging are calories, and the capital letter C is also marked, which is equivalent to the heat required to raise 1 000 grams of water from 14.5 degrees Celsius to 15.5 degrees Celsius at1atmospheric pressure, which is about equal to the internal energy of 4 186 joules. (1000 calories = 1 calories).

So, actually, this can of soda contains 200,000 calories (but don't worry, this also applies to sports. When the exercise chart says that you jog for 2 kilometers and burn 100 calories, it is 100 calories). In English, "calorie" (lowercase) means calorie, which is about 4. 186 joules, and "calorie" (uppercase) means calorie, which is about 4 186 joules.

The role of heat and metabolism:

Just as computers consume electricity and trucks consume oil, so do human daily activities. Heat not only provides energy for people's exercise, daily work and life, but also provides energy for human life activities, blood circulation, breathing, digestion and absorption. People who lose weight can burn fat through exercise, which can accelerate calorie consumption and achieve the goal of healthy weight loss.

Generally speaking, adults need at least 1500 kcal of energy every day to maintain body function, because even if you lie still, your body still needs energy to maintain body temperature, cardiopulmonary function and brain operation. Basal metabolic consumption varies with individual height, weight, age and gender. Human survival needs energy, which is obtained from food. The calorie content in food is a measure of how much potential energy food produces.

1g carbohydrate has 4000 calories, 1g protein has 4000 calories, and 1g fat has 9000 calories. Food is generally composed of these three substances. Therefore, as long as we know the contents of these three substances in food, we can know how much heat or energy food contains.