What is a healthy weight for a 58 year old male? The average American man 20 years old and up weighs 197.9 pounds . How many kgs is overweight? There are different categories of obesity as follows: Ideal (normal) BMI is 18.5 to 24.9 kg/m2. A BMI of 25-29.9 kg/m2 is overweight. A BMI of 30-34.9 kg/m2 is obese (Grade I).Is 40kg underweight?BMI values of less than 18.5 kg/m2 are considered...