I don't think you're less than 20% body fat. I'd guess you're around 24-25%. What does your exercise routine look like?
Oh, and I was wrong before. In men body fat percentage above 25% in men is obese. 18-25% is acceptable to overweight, 14-17% is fit, 6-13% is athletes. It's different for men and women.
http://www.healthchecksystems.com/bodyfat.htm