Greg Peyser and Benson Erwin never think of themselves as overweight.
As members of Johns Hopkins' top-ranked lacrosse team, they lift weights two to three times a week, and five days a week they run, scrimmage and hustle through a series of agility, shooting, passing and defensive drills
"I feel like I'm in the best shape of my life," said Erwin, 23, a senior majoring in international studies.
But all is not as it seems. Because both athletes are 6 feet 1 inch tall and weigh about 200 pounds, they're both overweight - according to federal standards - and so are most of their teammates.
So are most of the Baltimore Orioles, the Washington Nationals and many of the players on the teams that reached the Final Four in the NCAA's men's basketball tournament. That's because the government uses a calculation known as the body mass index, or BMI standard, to decide who's fat and who's not.
The BMI came under unusual scrutiny this week when federal researchers cited it in a report that lowered the projected number of deaths attributable to obesity to 112,000 a year - a third of the number the government estimated four months ago.
The study by the U.S. Centers for Disease Control and Prevention prompted many to question the way BMI is used to track obesity and its effects on our health.
Basically, BMI is calculated by dividing your weight by your height. Under current standards for adults over 20, a BMI of 18 to 24 is considered normal. A BMI of 25 to 29 makes you overweight, while 30 signals obesity, and 40 is considered extremely obese. If your BMI is less than 18, you're underweight.
Many physicians routinely use BMI to determine a patient's ideal weight, and researchers use it to calculate changes in the nation's waistline. "It is a useful tool for tracking weight gain over time," said Dr. Walter Willett, a researcher at the Harvard School of Public Health.
But critics say that the body mass index can be misleading and, in some cases, should be ignored. "I used to be really enthralled with the BMI, but not anymore," said Dr. Fred Pescatore, a New York physician and author of The Hampton's Diet.
Pescatore and other critics say the BMI fails to take into account that people have different bone mass and muscle tone. That makes BMI an ineffective measure for well-muscled athletes like Peyser and Erwin at one end of the scale, and for elderly people with more body fat and less muscle on their frames, at the other.
"I don't use it at all," said Glenn A. Gaesser, a University of Virginia physiologist and obesity researcher. Instead, he measures a patient's height and weight, then applies other barometers of fitness, such as exercise regimen and diet.
Others say BMI is one measure of overall health but isn't universally valid. "For the average person, the BMI is a reasonable indicator, but it doesn't work for everyone," said Dr. Roger Blumenthal, director of preventive cardiology at Johns Hopkins School of Medicine. "It's hard to make generalizations because of the different types of people, and groups of people you have out there."
In fact, a study last month by the Johns Hopkins Bloomberg School of Public Health confirmed what many experts have said for years - that the circumference of your waist may be a better indicator of health risks than BMI.
Researchers reviewed the records of 27,270 men over 13 years and found excessive waistlines could be used to predict the risk of diabetes and cardiovascular problems. For adult men, a waist size more than 40 inches is considered a danger sign. For women, it's 35 inches.
In practice, some practitioners use waist measurement as a fitness guideline today, but BMI is still the king. "The World Health Organization [WHO] set BMI as a standard years ago, and it's been that way ever since," said Dr. Youfa Wang, who conducted the Hopkins study.
CDC and other top research institutions collect BMI statistics to determine the scope of the nation's weight problem. And federal officials insist it's an effective tool.
"There is a relationship between your BMI and the likelihood of certain health outcomes," said Deborah Galuska, associate director for science in CDC's Division of Nutrition and Physical Activity. "The higher your BMI, the more likely you are to be at risk for cardiovascular disease, diabetes and other diseases."
The government estimates the cost of treating obesity and related problems at $98 billion to $129 billion a year. And by virtually any measure, the nation is getting fatter. Over the past decade, CDC says, obesity rates have increased by more than 60 percent among adults. Today, some 59 million adults qualify as obese.
"There's no question that people are getting bigger," said Dr. Soren Snitker, a diabetes and obesity researcher at the University of Maryland School of Medicine.