It's called reverse anorexia and it happens to men who believe they are too little and too frail and new research shows its driving men to inject steroids and suffer psychologically.
Muscle dysmorphia affects men whose have normal muscle mass but who believe their muscles are inadequate.
Sydney University research has found men with these body image issues are four times more likely than females with eating disorders to go undiagnosed.
And it says men with these conditions suffer more from depression because of the stigma associated with them seeking help for what is regarded as a female problem.
'The additional stigma towards men is that they are less masculine by virtue of suffering from a stereotypically female problem," the authors say in the study published in the Australian and New Zealand Journal of Public Health.
"In addition men report feeling less worthy if they need to ask for help, and this has been associated, in our research, with an increased likelihood of men with eating disorders remaining undiagnosed," the authors say.
"Because males are more stigmatising of eating and body image issues than females, if a guy has mostly male close friends, these friends are likely, on average, to be less supportive, than a female's close friends," the authors say.
The study found extreme dieting and purging increased more rapidly among males than females in the decade between 1998 and 2008. And the proportion of needle exchange services that reported that steroids were the last drug injected more than tripled from 2 per cent to 7 per cent from 2007-2012.
The study found men with binge eating problems were more likely to have quality of life and mental health problems than females with the disorder.
A study of almost 2,000 Australian men and women found seven in ten had some type of body dissatisfaction.
Sixty per cent of males were dissatisfied with their body in some way and 80 per cent of females were dissatisfied with their bodies.
Fifteen per cent of males had marked dissatisfaction with their bodies compared to 33 per cent of females. The study found there was some evidence to suggest males with eating disorders may have higher rates of compulsive exercise and anxiety disorders than females.