my BMI is in the 'underweight' range... not as low at 16 (where they classify you as anorexic) but still under 18. it's not unhealthy on me. i've stopped dieting, eat 100g of chocolate each day, drink full cream milk etc but still have a stable low weight. i just have a fast metabolism. and my ethnic heritage typically sprouts out people with small bone structures, so i don't think the BMI captures all of that.

it is a good basic tool, though.