Poor people or those who are less educated are unlikely to give up bad habits such as smoking and eating junk food, according to a report.
On the contrary, those who belong to the middle class are getting healthier by choosing better lifestyle, the report from the influential King's Fund health think-tank said.
Researchers analyzed official data from England covering four behaviors linked to disease and early death: smoking; excess alcohol use; poor diet and sedentary lifestyles, the Daily Mail reported.
These bad habits account for almost half the burden of ill health in developed countries and are linked to everything from heart problems and diabetes to cancer.
They found the number of people engaging in three or four of these risky behaviors fell from 33 per cent in 2003 to 25 per cent in 2008.
But the 'significant' change was very different among the social classes. The report found 'these reductions have been seen mainly among those in higher socio-economic and educational groups'.
Those with no educational qualifications were more than five times as likely as those with degrees to engage in four key damaging behaviors in 2008, compared with three times as likely in 2003.
It found the better off someone was, the more likely they were to have begun living a healthier life during 2003-08 - when the Labor government embarked on a campaign for healthier living.
"The widening gap is due to the improvement in those at the top, and, to a lesser degree, those in the middle, not because those at the bottom have got worse per se. They're stuck in a rut," said David Buck, a senior fellow at the King's Fund who was head of health inequalities at the Department of Health until 2010, who led the research.
Those from poorer backgrounds or with less education are also more likely to develop long-term conditions such as cancer and diabetes earlier and to experience them more severely, Buck added.