Some people are not fat in how to eat. The biggest physiological reason may be that the gastrointestinal system is weak, the digestive and absorption system cannot move normally, and the food they eat is excreted before being digested, so they will not be fat naturally.
There are also people whose physique is greatly influenced by their parents' genetic factors. Thin people are inherited by their parents. They have a high level of energy metabolism and consume more energy.
Many practical situations show that people who exercise more from childhood have high muscle content, high basic metabolism and more energy consumption. People with a high basal metabolic rate, even if they stay in bed, will burn more calories. Exercise can help improve the basic metabolic rate and regulate the body.
Therefore, the basic reason for this is that:
Physical reasons, high basic metabolic rate
There are two kinds of hormones that affect people's weight. The hormones that make people thin are adrenaline and thyroxine, which are in charge of metabolism. The hormones that make people fat are insulin.
When the hormone of thin is lower than that of fat, the body will tend to be overweight.
And when the hormone that is in charge of metabolism is secreted more in the human body, the human body tends to be thin. People with lean constitution have a high basic metabolic rate. A large part of their intake of calories is used for basic metabolism. The stored calories converted into fat are less, so they won't get fat easily.