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About Your BMI (Body Mass Index)

Optimal Weight Threshold Lowered
By Sally Squires
Washington Post Staff Writer
Thursday, June 4, 1998; Page A01

The federal government plans to change its definition of what is a healthy weight, a controversial move that would classify millions more Americans as being overweight.

Under the new guidelines, an estimated 29 million Americans now considered normal weight will be redefined as overweight and advised to do everything they can to prevent further weight gain. Those who are already experiencing health effects, such as high blood pressure, elevated cholesterol or diabetes, will be encouraged to lose small amounts of weight -- about six to 12 pounds -- to bring them back to safer weight levels.

The move has been debated for months within public health circles, since the guidelines set the standard for doctors to care for the overweight and the obese. They also address such thorny questions as when diet and exercise alone should be used to shed pounds and when drug treatment should be considered and for whom.

The guidelines use a measure called body mass index (BMI), which takes into account body weight and height to gauge total body fat in adults. Under the new guidelines, people with a BMI of 25 to 29.9 are considered overweight. For example, at 5 feet 3 inches, adults who weighed 141 pounds or more would be overweight, while those who are 5 feet 11 inches would be considered obese at 215 pounds.

"We felt that the record was clear and the risk was there," said Xavier Pi-Sunyer, a leading obesity researcher who chaired the expert panel that wrote the guidelines for the National Heart, Lung and Blood Institute, which is part of the National Institutes of Health. "We felt that we owed it to physicians and their patients to alert them to this fact, although it doesn't mean that everyone needs to go on a diet."

Under the new guidelines, 97 million adults -- nearly 55 percent of the U.S. population -- would be considered overweight, placing them at increased risk of such health problems as diabetes, elevated blood cholesterol, heart disease, stroke and high blood pressure.

The new guidelines, which bring the United States into line with the definition of overweight used by other countries as well as the World Health Organization, are designed to try to reduce the health problems caused by weighing too much, an increasing problem in the United States.

But critics say that the new guidelines would classify people as overweight who are not really facing a significant health risk because of their current size. They also worry that the new guidelines would unnecessarily stigmatize overweight people, who are already often struggling to win the battle of the bulge.

"The rationale behind these definitions is based on . . . data that shows increases in mortality with a BMI of 25 and above," said Judy Stern, an obesity researcher at the University of California at San Diego, and the only member of an NIH advisory panel to vote against endorsement of the guidelines. "They have misquoted the data . . . if they are going to do it scientifically, they should do it scientifically. I would not change public health policy on that."

Those at odds with some parts of the guidelines also fear that they will open the door to wider use of diet drugs. The use of diet drugs has come under question since the popular Redux and the phentermine-flenfluramine (fen-phen) combination were removed from the market after serious complications were linked to their use.

The guidelines call for diet drugs to be prescribed in ways consistent with Food and Drug Administration standards, that is, at a BMI of 27 when other risk factors such as diabetes or high blood pressure are also present. When no other risk factors occur, diet drugs should be reserved for use by those who have a BMI of 30 or more, according to the guidelines.

But obesity experts worry that by changing the definition of being overweight, doctors will be tempted to prescribe diet drugs sooner to help patients lose unwanted pounds. "I want to make sure that the treatment of obesity with drugs is balanced by the risk for being obese or overweight," Stern said. "It is a slippery slope. If the guidelines go out the way they are, there will be a big push to lower the BMI at which we treat with drugs and that's not justified, given the current drugs."

One of the most vocal critics of the guidelines has been former surgeon general C. Everett Koop, who has questioned lowering the cutoff point for what is considered overweight. "We have so many overweight and obese people in this country and we are trying desperately to get them down to weights that will be more protective," said Koop, whose organization, Shape Up America!, issued its own weight guidelines in 1996. "This makes it more complicated. I worry that people will say, `This goes too far. I quit.' I think it is like someone being in a race and saying they moved the goal line."

To formulate the new guidelines, the panel spent three years considering evidence from 49,000 scientific papers on obesity and overweight.

The final guidelines are scheduled to be officially released June 17. But the NHLBI released parts of them early after drafts were leaked by reviewers.

The guidelines represent a shift from the definition that has been used by other federal agencies. In past national health surveys, the National Center for Health Statistics has defined overweight as a BMI of 28 for men and 27 for women. Federal dietary guidelines released in 1996 set a healthy weight as a BMI of 25 or below for men and women.

According to the guidelines, those who fall into the BMI range of 25 to 34.9, and have a waist circumference of over 40 inches in men and 35 inches in women are at especially high risk for health problems.

The first goal for those who are overweight is to halt their weight gain, according to the guidelines. A second step is to try to lose weight through diet and exercise. "A reasonable time line for a 10 percent reduction in body weight is six months of therapy," a final draft of the guidelines notes.

© Copyright 1998 The Washington Post Company