Don's Sweat the Scale- Nancy Churnin

Taken from Chicago Tribune Health section- January 3, 2010

Trying to get fit? Stop worrying about being up or down a few pounds.

That's the consensus of doctors we asked to help us wade through the bewildering and sometimes conflicting number of ways to measure your fitness level.

BMI

What is it? Your most important number, according to all the doctors surveyed. Body Mass Index is your weight in kilograms divided by height in meters squared. Intimidating as that may sound, you can find BMI calculators online, including at cdc.gov (search for "BMI calculator.")

Your target: A BMI of 18.5 to 25 is ideal. A BMI of 25-30 is overweight. A BMI of over 30 is obese and brings a substantially increased risk of health issues, ranging from diabetes to depression.

Doctors warn that professional athletes may have a BMI that would be considered obese in an average person. Dr. Riva L. Rahl, preventive medicine physician and medical director at the Cooper Wellness Program in Dallas, estimates that tennis superstar Venus Williams may have a BMI that would classify her as overweight. Dr. Nick Nicholson, bariatric surgeon on the Baylor Plano ( Texas) medical staff, estimates that by BMI standards, many professional football players would be considered morbidly obese.

The doctors agree that you shouldn't judge your fitness by the standards of a professional athlete. At the same time, Nicholson adds that exercise is such an important component of fitness that people with a BMI of 30 who exercise four days a week have a lower risk of a heart attack than people with a BMI of 24 who don't exercise.

WAIST CIRCUMFERENCE

What is it? The number of inches around your waist as calculated by a tape measure at the smallest area above your belly button and not by your pants size.

Your target: For men it should be less than 40 inches and for women under 35 inches no matter what your height is.

WEIGHT

What is it? Your weight on a scale.

Your target: You can plot your goal according to your height and gender, but this is the least useful measurement, according to the doctors. Nicholson says he would rather see a patient focus on losing sizes rather than losing pounds.

FITNESS NUMBERS FOR KIDS

Dr. LeAnn Kridelbaugh, pediatrician and physician nutrition specialist at Children's Medical Center Dallas, says you can't apply adult fitness numbers to kids because kids are still growing.

"With kids these numbers are moving targets," she says. "A normal BMI or waist circumference for a 10-year-old would be horrific for a 5-year-old. Although there are some norms for waist circumference, we don't focus on them. Instead pediatricians plot a child's height, weight and BMI on a curve."

Kridelbaugh says pediatricians should establish on each visit what percentile a child falls in according to his or her age and gender. In general, if the BMI is between the 85th and 95th percentile for weight, the child is considered overweight, with over the 95th percentile being obese and over the 99th percentile morbidly obese.

But for most children the key is to see whether their percentile changes from year to year.

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The doctors' favorite numbers

150: Dr. Riva L. Rahl says if adults would log 150 minutes of aerobic exercise a week, they would significantly reduce their risk of cardiovascular disease, according to the Physical Activities Guidelines for Americans released last year (available at health.gov). And if they would mix in two weekly sets of strength training for 10 minutes at a time that would be even better, she says.

10,000: Dr. Nick Nicholson says adults could improve their fitness greatly by taking 10,000 steps each day, as recommended by several national societies. "Wear a pedometer," he recommends, noting that it can be fit easily into an ordinary day. "People who pace when they talk on the phone or are thinking have lower BMIs."