What’s the reason for being heavy when you don’t look fat?

Does not look fat weight but heavy weight is generally low fat content, high muscle content caused by.
For sports athletes or long-term fitness exercise crowd, the general weight is very heavy, due to long-term exercise, resulting in increased muscle content in the body, the fat content is reduced. Under the same volume, the muscle is heavier than the mass of fat, so there will be the phenomenon of not looking fat but weighing a lot.
To know whether your weight is in the normal range, you can refer to the calculation of BMI, i.e. weight (kg) divided by the square of height (m). If the calculated value is greater than 23.9, it is a case of overweight or obesity and requires scientific weight reduction.