As a result of the survey of 1,000 British men, funded by the medical group We Love Our Health, an online men's health awareness initiative has been launched.
The Big Check aims to encourage men to make a potentially lifesaving health check.
"Take off your clothes, stand upright and look down at your penis, if you can't see it, you are obese," the group's online doctor, Johan du Plessis said.
He urges men not to ignore it, as it can knock years off your lifespan but it can also put you in serious risk from life threatening illness.
Campaign member Dr Sarah Brewer urges men to adopt a healthier life style.
She said that most men care more about maintaining their cars than their own bodies and often only see the doctor if told by a partner or relative.
Being overweight means that men are more likely to develop Type 2 diabetes, colon cancer, high blood pressure, high cholesterol, heart disease and other health problems.
But, what the research does not spell out is that obesity has been linked to erectile problems and difficulties with sexual performance, the Sydney Morning Herald reported.
From a psychological point of view overweight men often feel uncomfortable with their body and have a lower self esteem.
They may suffer from anxiety, depression or emotional distress and therefore acquire performance anxiety. Unfortunately, it's not something they want to talk about, either to their GPs or a counsellor.
The social and psychological obstacles these men face are not the only factors causing sexual problems. There is also a direct biological origin.
To have an erection is the result of increased blood flow in the penis and to maintain penile erection depends on a healthy circulatory system.
Overweight men should view the prospect of impotence as a compelling motivation to lead a different lifestyle; one that involves regular exercise and a healthy diet. It is for their own sake and that of their partners.
Erectile dysfunction does not just affect overweight men. The world's largest study to examine links between erectile dysfunction and heart disease found even minor erection difficulties in healthy fit men, can be an indicator of future heart risks.