The study examined data on height, weight and overall fitness from a Swedish registry of 1,668,893 men who enlisted in compulsory military service between 1969 and 2005, when the men were 18 or 19.The researchers then used two other national databases that track the causes of all hospitalizations and deaths in Sweden to determine whether the men had serious heart disease as they aged, and followed them for up to 46 years. The findings were published in American Heart Association’s journal Circulation.
“We were interested in studying cardiomyopathies, because heart failure caused by this historically uncommon disorder doubled in Sweden between 1987 and 2006,” said Annika Rosengren, co-author of the study.
Among the men in the study, 4,477 were diagnosed with cardiomyopathy at an average age of 45.5 years. The men who were lean at age 18 – with a body mass index (BMI – measure of body weight) below 20 – had a low risk of cardiomyopathy. However, that risk steadily increased as weight increased, even among men on the high end of a normal BMI (22.5-25).
There are several types of cardiomyopathy, but the causes are poorly understood. In one form, called dilated cardiomyopathy, the heart muscle becomes weak and can’t pump blood efficiently. In another, called hypertrophic cardiomyopathy, the heart muscle becomes stiff and isn’t able to fill with blood properly.
Cardiomyopathy can reduce heart function and lead to heart failure, which means the heart is not able to pump blood properly.
In the study, men who had a BMI of 35 and over in their youth were eight times more likely to develop dilated cardiomyopathy as adults compared to men who were lean in their youth. It was not possible to estimate increased risk for hypertrophic cardiomyopathy in men with BMI 35 and above because there were too few cases to provide a meaningful analysis.