Body mass index will tell you if you are physically fit
Body mass index or BMI is a formula wherein you will know if your weight is healthy for your height. There are many online BMI calculators. You can check if your BMI is of the healthy range. Actually, this is your basis:
Less than 18.5 is considered underweight
Healthy range is from 18.5 to 24.9
More than 24.9 is overweight
30 or more is technically obese
Science provides the data for you, man.