His study looked at 2,139 16-year-old boys in 1996 who were followed for 13 years.
The boys were asked to rate their current weight ranging from "very underweight" to "very overweight", which researchers compared to the participants' BMI.
Those who perceived themselves as far too skinny, but were an average weight or higher, were the ones with the highest level of depressive symptoms
His second study found that 4 per cent of the participants who inaccurately perceived themselves as underweight admitted to using steroids.
"Unfortunately, there is little evidence-based research on effective therapies for steroid use among adolescent boys," he said.
"However, cognitive-behavioral therapy has proven to be effective for body image concerns and could be helpful for boys considering using or already using steroids."
He advises clinicians working with depressed teenage boys who feel they are being bullied for their underweight appearance should be mindful of steroid use.
- DAILY MAIL