YOUR HEALTH
Obesity defined
DR. DONOHUE

DEAR DR. DONOHUE: I feel lost. Everybody says I'm obese. I am 5 feet 7 inches and weigh 270 pounds. I am a 48- year-old male. I swim three to five times a week. I feel good. I recently had a stress test for my heart. I came out with flying colors. Why am I being told I am obese? I have a 52-inch chest and a 50-inch waist. -- E.D.

ANSWER: Obesity is a health threat, just as is cigarette smoking. It leads to heart disease, high blood pressure, some cancers, diabetes, stroke, gallbladder disease, GERD and osteoarthritis. It is a major contributor to early death. These are not unsubstantiated speculations; they are proven facts.

Body mass index, BMI, is the standard by which obesity is defined. It's obtained by dividing weight in kilograms by height in meters squared (or weight in pounds divided by height in inches squared and then multiplying the result by 703). It correlates better with body fat and takes into account body height. It's not without faults. The heavily muscled often have a BMI that puts them in an overweight or obese class when most of their body weight is muscle -- healthy weight. For the rest of us, it is fairly reliable. The normal BMI is 18.5 to 24.9. Yours is over 40, and that puts you in the "obese" category.

Your waist measurement is another sign that all is not well. A man should have a waist measuring less than 40 inches (102 cm), and a woman, less than 35 inches (89 cm). Larger waist sizes indicate too much body fat.

Can a person be overweight but be quite healthy? Physical fitness reduces the danger of obesity but doesn't entirely negate it. The risk of illness for an obese person is 50 percent greater than for a person of normal weight. If the obese person is physically fit, the risk of illness drops to 30 percent.

Your stress test was normal, and that's reassuring. However, if you don't lose some weight, it's liable not to remain normal. Keep swimming. Increase the time you swim. You must start cutting back on calories so you can lose some weight. Exercise alone rarely succeeds in significant weight reduction.

DEAR DR. DONOHUE: I have read that you must sleep between 10 p.m. and 2 a.m. for your body to repair itself. Is this true? Or is any time of day OK as long as you sleep in the dark? - - L.

ANSWER: During a one and a half to two hour sleep cycle, we pass through five stages of sleep. With eight hours of sleep, therefore, we experience four or five such cycles. Stages three and four are called "deep sleep," and together they occupy 12 to 24 minutes. During those stages, growth hormone is at its peak blood concentration, and that's the period during which most body repair takes place. Those sleep stages occur throughout the night, not just between 10 p.m. and 2 a.m. They occur if one sleeps during the day. You don't have to sleep in the dark if you can get to sleep when it's light. I cannot.

Dr. Donohue regrets that he is unable to answer individual letters, but he will incorporate them in his column whenever possible. Readers may write him or request an order form of available health newsletters at P.O. Box 536475, Orlando, FL32853-6475. Readers may also order health newsletters from www.rbmamall.com. 2006 North America Syndicate Inc. All Rights Reserved