Body Mass Index and the Link to Heart Disease or Stroke

Medicine does not follow the algebraic formula many of us learned in school, where if A equals B and B equals C, then A equals C. Often the cause of one condition (A equals B) which can lead to another condition (C) does NOT mean that the cause of the first condition is also the cause of the second.

Take heart attacks and stroke, for instance. We know that those who are overweight or obese are at a higher risk for high blood pressure, poor cholesterol scores and diabetes, which are all known risks for heart disease and stroke. (For those doing the math at home: A is overweight or obese; high blood pressure, poor cholesterol scores and diabetes are B; and C is heart disease and stroke.) But what we don't know for sure is if A = C (overweight or obesity are causes for heart disease and stroke). Medicine just isn't that linear.

On the other hand, sometimes it is - at least statistically.

A study in the American Heart Association's academic journal, Circulation (2008; 118(2):124-130), made use of data gathered in a study which involved almost 4800 men and women and lasted from 1971 to 1995. The initial gathering of data in 1971 included age, gender, smoking status, height and weight (Body Mass Index), blood sugar levels (diabetes), and cholesterol scores.

The scientists measured the time elapsed from the beginning of the study to a participant's first diagnosis of heart disease (including heart attack or angina) or cerebrovascular disease (including stroke or transient ischemic attack). They then calculated the participants' risk of heart disease or cerebrovascular disease based solely on their Body Mass Index, then performed the same calculations, but taking into account the presence of the other known risk factors.

An additional 4.3 points in a participant's Body Mass Index meant, by itself, an increase in risk of heart disease or stroke of over 25%. When the other risk factors were taken into account, that 4.3 point difference meant only a 10% increase in risk. That's still a significant effect!

What this means for you

This is exciting (and yet sobering) news. For a woman who is 5'4", decreasing her Body Mass Index four points, from overweight to normal weight, would mean losing about twenty pounds. A man who is 5'10” would have to lose about thirty pounds. If your Body Mass Index is in the overweight or obese range, take action today to protect yourself from heart disease and stroke. Here's one idea you can start today: during lunchtime, get out and walk for twenty to thirty minutes.

First posted: September 24, 2008