Question of the Week

July 23, 2007


Even if they don't quite understand it, most people have heard the term, "BMI."

"Body Mass Index (BMI) is a number calculated from a person’s weight and height. BMI is a reliable indicator of body fatness for people. BMI does not measure body fat directly, but research has shown that BMI correlates to direct measures of body fat ... Additionally, BMI is an inexpensive and easy-to-perform method of screening for weight categories that may lead to health problems."
U.S. Centers for Disease Control and Prevention

For years, health care professionals have stressed the importance of having a "healthy" BMI for both adults and children, but knowing a person's BMI is not enough to determine if that person is healthy -- or even if that person has too much body fat.

"BMI is used as a screening tool to identify possible weight problems for children. CDC and the American Academy of Pediatrics (AAP) recommend the use of BMI to screen for overweight in children beginning at 2 years old. For children, BMI is used to screen for overweight, at risk of overweight, or underweight. However, BMI is not a diagnostic tool. For example, a child may have a high BMI for age and sex, but to determine if excess fat is a problem, a health care provider would need to perform further assessments. These assessments might include skinfold thickness measurements, evaluations of diet, physical activity, family history, and other appropriate health screenings."
U.S. Centers for Disease Control and Prevention

To complicate things further, what is considered a "healthy" BMI varies by age for children and teens.

"Figuring out the body mass index is a little more complicated for teens than it is for adults (that puberty thing again). BMI charts for teens use percentile lines to help individuals compare their BMIs with those of a very large group of people the same age and gender. There are different BMI charts for guys and girls under the age of 20. ..."
Kids Health

The following site provides access to both an adult BMI calculator and a child and teen BMI calculator:
U.S. Centers for Disease Control and Prevention

While an online resource can help a person figure out his or her BMI -- and even plot that score to show percentile -- it can be confusing when trying to figure out what all that means.

"Although you can calculate BMI on your own, it's a good idea to ask your doctor, school nurse, or fitness counselor to help you figure out what it means. That's because a doctor can do more than just use BMI to assess a person's current weight. He or she can take into account where a girl or guy is during puberty and use BMI results from past years to track whether that person may be at risk for becoming overweight. Spotting this risk early on can be helpful because the person can then make changes in diet and exercise to help avert developing a weight problem. People don't like looking overweight, but weight problems be more serious than someone's appearance. People who are overweight as teens increase their risk of developing health problems, such as diabetes and high blood pressure. Being overweight as a teen also makes a person more likely to be overweight as an adult. And adults who are overweight may develop other serious health conditions, such as heart disease."
Kids Health

Hearing that there are health concerns associated with being overweight is nothing new for most people, but there is more to it than just being a "healthy" weight.

"Some doctors now believe the internal fat surrounding vital organs like the heart, liver or pancreas -- invisible to the naked eye -- could be as dangerous as the more obvious external fat that bulges underneath the skin. 'Being thin doesn't automatically mean you're not fat,' said Dr. Jimmy Bell, a professor of molecular imaging at Imperial College, London. ... According to the data, people who maintain their weight through diet rather than exercise are likely to have major deposits of internal fat, even if they are otherwise slim. 'The whole concept of being fat needs to be redefined,' said Bell... Without a clear warning signal like a rounder middle, doctors worry that thin people may be lulled into falsely assuming that because they're not overweight, they're healthy. 'Just because someone is lean doesn't make them immune to diabetes or other risk factors for heart disease,' said Dr. Louis Teichholz ... Even people with normal Body Mass Index scores -- a standard obesity measure that divides your weight by the square of your height -- can have surprising levels of fat deposits inside."
CBC (Canadian Broadcasting Corporation)

A high BMI can serve as a warning to some, while a normal, or even low, BMI can provide a false sense of security to others. Being thin does not necessarily mean being healthy.

"In books, in medical journals and at public health conferences, scientists have been dueling over the relative importance of fatness vs. fitness, and whether there is any common ground between the two camps. A small but vocal cadre of researchers has been challenging conventional wisdom, arguing that not only is it possible to be both fat and fit, but fitness is actually more important for health. 'All too often, medical professionals say it's the obesity we have to cure. That's the be-all and end-all. It's not... The impression is that everyone who is overweight faces an elevated risk for mortality. That's simply not true.' Other experts, however, maintain that while there may be exceptions, the evidence is clear for most people: Being overweight significantly increases the risk of a host of debilitating and often deadly health problems, including heart attacks, strokes, cancer and diabetes."
Washington Post

How much weight a person has -- or doesn't have -- may be fairly easy to see and/ or measure. However, a person's weight and/ or BMI score alone can not determine how healthy that person is.

Recently, doctors have found a way to measure the hidden "internal fat surrounding vital organs like the heart, liver or pancreas" that can cause health problems in those who appear healthy from the outside.

"Measuring blood levels of a chemical transporter for vitamin A [called retinol-binding protein (RBP4)] may be useful in estimating a person's "intraabdominal fat," a type of fat inside the abdomen that it not visible, but still adversely affects health, new research shows. ... Increased blood levels of RBP4 'appear to be a very good indicator of insulin resistance and increased intraabdominal fat, two risk factors that are notoriously difficult to assess... since they require complicated biochemical testing and advanced imaging techniques' ... As noted, increased levels of the protein were seen in subjects with high amounts of intraabdominal fat and in those with insulin resistance. In fact, RBP4 was a better predictor of intraabdominal fat and insulin resistance than several other blood tests that were evaluated. Monitoring RBP4 levels 'may one day provide a simple tool for assessing these risks and tailoring treatments in patients," Graham concludes. In addition, the current RBP4 findings may help explain why high levels of intraabdominal fat increase the risk of heart attack and stroke.'
New Zealand Herald

Thin people who don't exercise may not be healthy. Overweight people who do exercise may be more fit and have fewer health problems than those who are thin yet don't exercise. Does this mean that weight doesn't matter?

"Willett is also concerned that turning the focus away from weight will keep people from being vigilant about preventing weight gain in the first place, which is the most effective strategy. 'One of the big problems is by the time people become overweight or obese it's very hard for them to become active. They've developed arthritis or other problems that makes it hard, which is why we have to pay attention to weight early on.'"
Washington Post

Thin people who also exercised and were "fit" had the fewest risk factors for heart disease and stroke. Overweight people who did not exercise had the most risk factors. Weight is still an issue, but it is not the only issue.

Questions of the Week:
What lifestyle decisions do you need to make to get and stay at a healthy weight and fitness level for you? What risk factors do you have that might not be obvious? What information do you need to provide when working with a health professional to determine the best healthy living plan for your body type? What role should weight management play in this plan? What role should exercise play?

Please email me with any ideas or suggestions.
Note: Due to increasing amounts of SPAM sent to this account, please include "QOW" in the subject line when sending me email.

I look forward to reading what you have to say.

Health Community Coordinator
Access Excellence @ the National Health Museum

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