The Buzz: BMI

Some of my clients have asked me my opinion about BMI, or Body Mass Index. I don't mention it often or use it to measure their progress, but it's still making headlines in the news and magazines, nonetheless.

Fitness Matters, the American Council on Exercise's professional journal, does a great job of
describing the limitations of using BMI in its May / June issue.

BMI has several significant drawbacks. It can give a skewed result for some individuals and subgroups of the population. Jay Hoffman, a professor of health and exercise science at the College of New Jersey, says that BMI's main drawback is that "it just indexes height versus weight and doesn't take into account body composition."

Bodybuilders and elite athletes end up with a high BMI score because of the extra weight associated with muscle. So do fit civilians. (The article's author, Jim Gerard notes that while he is) hardly a body builder, but (he) work(s) out every day and at 6'2" and 210 pounds, (he has) a BMI result that puts (him) in the "overweight" category despite the fact that he has a 34" waist and a flat stomach. Conversely, taller people carrying a lot of fat may have a body mass index score that falls within the acceptable range.
BMI can also skew results in the opposite direction, as it does in the elderly, who tend to have scores that underestimate their excess weight or obesity because they have much less muscle than the average person.
Miller adds that BMI is not accurate when measuring the body composition of children or some small-boned women who, despite being petite, may have a small bone and muscle mass and a high percentage of body fat.
Another limitation of BMI is that it doesn't address the location of one's body fat, which is arguably a more telling indicator of overall disease risk. Abdominal fat in particular is linked o heart disease, poor lipid profiles and type 2 diabetes. And it's more likely to lead to changes in hormone levels that cause inflamed and eventually clogged arteries. Miller says, "The theory is that abdominal fat is more mobile and that it enters the circulation more readily to form arterial plaques."
Therefore, it's quite possible to have an acceptable BMI while carrying a potentially dangerous spare tire. And certain groups of people--those from Japan and south Asia, for example--that tend to stay relatively slender can still have an increased risk of heart disease from storing unhealthy amounts of abdominal fat.

Can You Pinch More than an Inch?

The scale may say that you're slim, but your frame may still be carrying too much body fat, says Michele Olson, Ph.D., a professor of exercise science at Auburn University. "Women with little muscle tone may not be overweight but still have unhealthy levels of body fat," she explains. A new Italian study found that normal weight women with higher than 30% body fat are at greater risk for heart disease. To learn you fat level, try one of two tests available at many gyms: calipers, which assess skin thickness at key areas, and bioimpedance devices, which send an undetectable electrical current through the body to read the ratio of fat to other tissue. Both are reasonably accurate when used by a trained professional.

Another Reason to Avoid Trans Fats

Belt size increasing? It may be the kind of fat you're eating--and not the total amount you consume each day--that contributes to weight gain. Researchers at Wake Forest University in North Carolina found that monkeys that ate trans fats gained four times the weight as monkeys eating the same amount of unsaturated fats.

How It Works: the Body-Fat Scale

You've used them before: body-fat scales. But do you know how they work?

Step 1: When you step on the scale's electrodes, a 500 microampere current shoots up your leg. Human skin can sense currents only stronger than 1 milliamp, which is twice as powerful as this charge.
Step 2: As the current moves throughout your lower body, it encounters resistance in tissue. Water is a much better conductor than fat, so muscle--which is about 73 percent water--provides easier passage.
Step 3: The scale detects the total time it takes for the current to compete its path. The faster it travels, the more muscle and less fat you have. With this data, it computes your body-fat percentage.

Personal experience leads me to advise that you empty your bladder before using the scale to estimate body fat percentage.

Beer Belly

How Beer Makes You Fat

Leave it to Men's Health Magazine to it down....

1. You take a swig of beer.


2. Within seconds, the beverage passes through your esophagus and into your stomach.


3. Twenty percent of the alcohol is absorbed into your bloodstream; the rest is absorbed into your intestines.


4. The alcohol travels through our blood to your liver, where it is broken down. During this process, waste products called acetate and acetaldehyde are created.


5. Acetate and acetaldehyde signal your body to stop burning fat. At the same time, your body starts making fat from another waste product of alcohol, acetyl CoA.


6. Your body can effectibely process only 0.5 to 1 ounce of alcohol per hour.


So the more you drink, the longer your body is inhibited from burning fat, and the more fat builds up from the excess acetyl CoA.

A 12-ounce beer contains about 0.6 ounces of alcohol.
The following contain 0.6 ounces of alcohol:

• 5.5 ounces wine (11% alcohol)


• 14.3 ounces of light beer (4.2% alcohol)


• 1.5 ounces of hard liquor such as whiskey (40% alcohol/ 80 proof)


• 1.2 ounces of hard liquor (50% alcohol/100 proof)

The above calculations are based on the percentage of alcohol present in each beverage, so the alcohol percentage or proof is given. For example, wine can sometimes be more than 11% alcohol. If you would like to learn more about calculating the amount of alcohol in your drinks, please visit www.elegantpie.com/cheers.html for formulas to help you calculate the ounces of alcohol in your drinks as well as blood alcohol content.

What's the point? If you're trying to lose fat, cut out alcohol for a while. You'll see and feel your results faster.