A body weight widely considered a healthy target by federal officials may still carry considerable health risks, a new study by Harvard researchers shows.
Since 1998, a body mass index of 18.5 to 24.9 has been considered a healthy target. But, according to the study, people in the higher range of healthy weight--those with a body mass index of 22 to 24.9 (or about 130 to 145 pounds for someone 5 feet 5 tall, and 150 to 170 for someone 5 feet 10)--still face significantly increased risks for a variety of illnesses, from diabetes to heart disease.
"It's quite striking," says Alison E. Field, assistant professor of medicine at Harvard and lead author of the study, which appeared last week in the Archives of Internal Medicine. "It really suggests that the health risks [of extra weight] may have been underestimated." The findings are drawn from two longitudinal studies of more than 120,000 middle-age female nurses and some 50,000 men who are also health professionals.
While the overall risk is still less than that for people who are overweight or obese, the team of researchers noted that women in the "high healthy" BMI range have twice the risk of diabetes as those with an even lower BMI--between 18.5 and 21.9. They also found a 40% increased risk of both gallstones and high blood pressure, and a 30% greater risk of high cholesterol and colon cancer among the heavier women.
Men in this "high healthy" range also were more likely to have health problems: They had a 90% increased risk of colon cancer, an 80% higher chance of diabetes and a 50% increased risk of high blood pressure.
Body mass index is a measure of fatness that takes into account height and weight. A person with a BMI of 18.5 to 24.9 is considered to be in the healthy range. Those with a BMI of 25 to 29.9 are considered to be overweight; and those who measure 30 and above qualify as obese.
So does this mean that Americans who by good fortune or hard work have reached a BMI of just under 25 should try to get slimmer still?
"We're not suggesting that everyone get down to a BMI of 18.5 to 21.9, although that is the healthiest BMI to have," Field says. "But it's important to realize that one is not risk-free when you reach that BMI of 25. It gives people a false sense of security to think that as long as I am not overweight, my health risk is very low."
Doctors need to better monitor and counsel patients who are gaining weight before they become overweight, Field says, since losing weight is so difficult. "At the very least, holding weight steady as you grow older would be preferable," she says.