Scientists are puzzled by recent findings indicating that obese(肥満の)heart attack patients have a higher survival rate than normal weight patients. Investigators found the mortality rate(死亡率)among obese patients was a mere 2.2%, as opposed to the 4.3% rate found in normal weight patients. Several theories have been proposed to explain this phenomenon. One possibility is that the hearts of obese victims are more accustomed to being stressed and can therefore withstand the strain of a heart attack.