Check you BMI (Body Mass Index). To do that...Multiply your weight in pounds by 705.
Divide that number by your height in inches, and then divide it again by your height in inches.

So that means for 5 feet 9 inches or 69 inches:

705 X 166 = 117,030

117,030 Divided by 69 = 1696

1696 Divided by 69 = 24.6

Scientists at the National Institutes of health have determined that a BMI under 18.5 is considered very low risk for heart disease, diabetes, and high blood pressure, 18.5 to 24.9 is low risk, 25 to 29.9 is considered overweight and high risk, and 30 or above is considered obese and very high risk.

(I got this info from the book 'The Lance Armstrong Performance Program' pg. 123).