What is a healthy body weight?

It is all to do with your BMI (body m index), the ideal is '20', I can't remember the calculations for you but it's to do with your height/weight ratios etc. Obviously underweight is below 20, 20 is 'normal' obese is approx 25 & morbidly obese 30 onwards as I said these are not perfect quotes google BMI & that should tell you how to work it out (unless you own a wi fit, & it does it for you). Hope I have been a little help to you.