DEAR DR. DONOHUE: Could you please explain why my body mass index – BMI – is 35? I am 5 feet 2 inches tall and weigh 115 pounds. Why is my BMI so high? – A.P.

ANSWER: How about you and I going through the calculation of your BMI together? Something is wrong with the answer you are getting.

Body mass index is a much more reliable indication of how much body weight is fat and how much is made up of bone, muscle, etc. That is something a scale cannot tell you.

First, take your height in inches and square it. Your height is 62 inches. Sixty-two inches squared (62 x 62) is 3,844.

The second step is to divide your weight in pounds by the answer obtained in the first step. For you, that would be 115 divided by 3,844. The answer is 0.029.

The third step is to use that last figure, 0.029, and multiply it by 703. That comes out to be 20.38. That is your BMI.

A normal BMI lies between 19 and 25. Yours is as good as it can get.

Readers who use the metric system can calculate their BMI by dividing their weight in kilograms by their height in meters squared.

DEAR DR. DONOHUE: I have a beer belly without drinking beer. My stomach extends out like I swallowed a medicine ball. The quantity of food I eat is small. Is there some exercise that can help me? – B.B.

ANSWER: There is no exercise that selectively removes fat from the abdomen. When the body burns fat for fuel, it takes the fat from all fat depots throughout the body. However, by increasing the amount of your exercise without increasing the amount of calories you eat, the abdomen loses some of its fat.

Posture is the next place to cure a protruding abdomen. Stand with your back against the wall. If you can put your fist between your lower back and the wall, your lower back sways too far inward. The inward back sway makes the stomach stick out.

To flatten the lower back, stand against the wall again. Make a conscious effort to have the lower back touch the wall. That gives you an idea of the muscles that can reduce the back’s inward sway. Adopt that posture all day long.

Abdominal exercises are not going to remove abdominal fat. They do, however, strengthen abdominal muscles, and those muscles will act as a girdle holding the stomach in. A good abdominal exercise is done lying on the floor with your lower legs resting on the seat of a chair. The knees should be bent to 90 degrees. Slowly lift your head and shoulders off the floor. Don’t push the head down toward the chest. Keep it in line with your back. When the shoulder blades clear the floor, hold that position for five seconds. Return to the starting position and repeat the exercise as many times as you can.

DEAR DR. DONOHUE: I am an assistant coach for a high-school football team. I was brought up never to drink cold water when exercising, as it would cause stomach cramps. My players say I am all wet. They want cold water. Are they correct, or am I? – J.B.

ANSWER: It’s OK to drink cold water during practice. You can even make it ice water. Cold water passes through the stomach faster, and that more quickly restores the fluids the body has lost from sweating. Ice water also helps keep the body temperature down.

You can give credit for this information to Dr. William Evans of the University of Arkansas.

DEAR DR. DONOHUE: I am 88 and work out in the gym one and a half hours six days a week. Our local supermarket had a great deal on Diet Coke, and I bought a big supply. Can this be used for some of the water the body needs? – J.R.

ANSWER: Yes, it counts as a fluid replacement. Don’t make it your only drink, but don’t hesitate to drink it.

DEAR DR. DONOHUE: My doctor tells me I have a leaky heart valve. He is quite nonchalant about it. I am worried sick. What can I do to fix the leak? – B.A.

ANSWER: You can do very little about repairing a heart valve leak.

The heart has four valves. They keep blood flowing from heart chamber to heart chamber. A leaking valve means that some blood that has entered a downstream chamber flows back into the chamber it just left. If the leak is significant, the heart pumps less blood than it normally does, and the body is shortchanged its oxygen supply.

What a leaky valve means to an individual depends on which valve leaks and how great the leak is. Often a doctor hears a heart murmur due to the leak. The doctor can frequently assess the seriousness of the leak by the quality of the sound it makes and where the murmur is best heard. If doubt about the leak lingers, an ultrasound picture of the valve determines its significance.

I can’t believe any doctor would let a serious valve leak go unattended. Call the doctor up and say you want to know the extent of the leak and if it needs correction. Correction usually involves surgery.

Readers can obtain the newly written pamphlet on heart valve problems by writing to: Dr. Donohue — No. 105, Box 536475, Orlando, FL 32853-6475. Enclose a check or money order (no cash) for $4.50 and the recipient’s printed name and address. Please allow 4-6 weeks for delivery.

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, FL 32853-6475.