This website says a healthy BMI (body mass index) is between 18.5 to 25 for male and female. If you google bmi calculator then google shows a BMI calculator for you. For a male 5 foot 10 inches you need to enter a weight of 129 lbs (87 kg) to get it to 18.5.

Isn't 129 lbs for a 5'10" male consider anorexic? That really surprises me that such a weight would be consider in the region of ideal healthy weight.

Ideal Weight Calculator

Google BMI calculator
bmi calculator - Google Search