Heat refers to the thermal interaction between the system and the outside world when the change of system state comes from the destruction of thermal equilibrium conditions, that is, when there is a temperature difference between the system and the outside world. As a result, energy is transferred from a high-temperature object to a low-temperature object, and the energy transferred at this time is called heat.
Heat and work are two different forms of energy transfer that accompany the change of system state, and they are measures of different forms of energy transfer. They are all related to the intermediate process of state change, so they are not functions of system state.
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The human body consumes energy all the time, which is provided by thermogenic nutrients in food. Nutrients that can generate heat in food are protein, fat, sugar and carbohydrate. They are oxidized to generate heat for the body to maintain life, grow and develop and exercise. When the heat energy supply is too much, the excess heat will become fat and be stored. After a long time, the body will get fat.
There are three main ways of calorie consumption. The first part is basal metabolic rate, which accounts for about 65-70% of the total calorie consumption of human body. The second part is physical activity, which accounts for about15-30% of the total calorie consumption. The third part is the thermal effect of food, which accounts for at least about 10%. The proportion of these three has been basically fixed.
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