A 2005 study published in the American Journal of Medicine by scientists at Duke University examined nearly 16,000 people in 37 countries. The authors found that one year after a heart attack, the death rate for normal-weight patients was 4.3 percent. For obese patients, it was just 2.2 percent.

Several other studies have confirmed those findings, including a paper last month in the European Heart Journal. German and Swiss doctors tracked more than 1,600 patients for three years after their heart attacks, and concluded that only 3.6 percent of fat patients had died, against nearly 10 percent of normal-weight patients.

However, experts warn, the results should not be used as an excuse for the overweight to indulge.

"We really don't want people to think that they should put on a bit of weight to have a better chance with their bypass surgery,"