The research is based on an online survey of 320 people
People with mental health problems are likely to avoid gyms and physical exercise due to embarrassment and fear of being judged, a survey has found.
The Scottish Association for Mental Health (SAMH) said it helps explain why people with issues like depression are more likely to become obese.
The survey also found people with mental health problems were four times more likely to have diabetes.
SAMH said obesity and mental health issues must not become closely linked.
Out of 112 people with mental health problems who were questioned, 9% said they would be too embarrassed and 11% said they worried people would judge them.
Of the 138 people who did not have a mental health problem, 1% said they would be too embarrassed and 2% were concerned about being judged.
Billy Watson, SAMH chief executive, said: "Our research presents compelling evidence that people with mental health problems often feel unable to attend local exercise facilities.
"This must be addressed by ensuring that such facilities do not discriminate against people with mental health problems.
"We believe it is crucial that mental health problems and obesity do not become an inevitable partnership and immediate action is required to address this."
SAMH questioned 320 people through its website on aspects of physical and mental health between 10 August and 20 September this year.
Out of those quizzed 112 said they currently had a mental health problem, 67 said they had a problem in the past and 138 said they had not had a mental health problem.
The research also found that people with mental health problems were more likely to be unable to afford to buy more fruit and vegetables, more likely to have sought help to reduce their alcohol consumption and experienced physical health problems.
Men with current mental health problems were twice as likely as men with no mental health history to drink more than the recommended 21 units per week.
The questionnaire also found people with current or previous mental health problems were more likely to smoke and have more than 20 cigarettes per day.
Peter Rice, Chairman of Royal College of Psychiatrists Scotland and Consultant Psychiatrist, said: "This important survey by SAMH shows the importance of mental health issues in Scotland's health challenges.
"The high rates of diabetes and high blood pressure identified will be contributed to by the barriers which people with mental health problems face in accessing exercise facilities."