The National Cholesterol Education Program says you should limit your intake of fat to 30 percent of the calories you consume each day. But don't think that will lower your cholesterol or body fat much -- unless, of course, you add regular exercise.
The average American gets 37 percent of daily calories from dietary fat. That's a lot of fat! A high-fat diet is linked to an increased risk of both heart attacks and cancers, the causes of 75 percent of the deaths in this country. A recent study published in the New England Journal of Medicine showed that adding just a moderate amount of exercise to a 30-percent-fat diet program can help lower body fat and cholesterol.
Sure, if you reduce your intake of fat to fewer than 20 grams each day, you can lower your body fat and blood cholesterol levels significantly, even without exercise. But limiting yourself to just 20 grams of fat will take major dedication -- Americans eat, on the average, 85 grams of fat each day. You would have to severely restrict your consumption of meat, chicken and dairy products made from whole milk; bakery products, except those low in fat; butter, margarine, mayonnaise, oily salad dressing, nuts and seeds; and everything that contains more than 2 grams of fat per serving.
If you exercise regularly -- and reduce your intake of fat to only 30 percent of your calories -- you probably can eat these "fatty" foods in moderation. Simply avoid basing your meals on fatty foods and start each meal with low-fat foods, such as fruit, vegetables, grains and beans.
Q: My doctor wants me to take an inhaled-steroid medication to treat my asthma. Are such drugs safe?
A: Asthma is an obstruction of air flow caused by a swelling of the linings of the tubes that carry air to and from the lungs. Of the many medications used to treat asthma, cortisone-type steroids control asthma more effectively than other drugs -- such as cromolyn -- that are taken orally or inhaled. And recent research shows that when inhaled, cortisone-type steroids are probably as safe as the other, less-effective drugs.
However, taken by mouth, cortisone-type steroids -- such as prednisone -- have two serious side effects. They can shut off your own natural production of cortisone so, if you're in an accident, you could go into shock. Steroids also can cause osteoporosis, a weakening of the bones, which makes them more likely to break.
Usually, inhaled steroids do not stop the body from making its own cortisone, and exciting new research from Nassau County Medical Center in East Meadow, N.Y., shows that inhaled steroids most likely do not cause osteoporosis.
Asthma often cannot be controlled with the usually prescribed cortisone-type steroid dosage of two sprays, four times a day. Still, in most cases, doubling the dosage to four sprays, four times a day will control asthma and usually will not stop the body from making cortisone.
Thus, the side effects of inhaled cortisone-type steroids appear to be minimal, when compared to their benefits.
Q: Will fasting before a game improve my endurance?
A: Before a game, say your prayers and eat lots of food, but never fast!
Articles have appeared in some sports journals encouraging athletes to fast before competing. Fasting can only harm your performance. Such poor advice comes from a misinterpretation of research reported in the Journal of Applied Physiology. That article indicated that rats could run farther after fasting for 24 hours than they could after they ate.
How long you can exercise a muscle depends on how much energy-packed sugar you can store in that muscle before you start to exercise. Fasting prior to exercise prevents replenishment of stored muscle sugar and reduces the amount of time that the muscle can be exercised before it feels tired and weak.
How then can laboratory rats increase their endurance by fasting? Evidently, fasting increased the rate that the rats' muscles used fat for energy, thereby conserving muscle sugar, so that the stored muscle sugar lasted longer. However, this does not apply to humans; we are not like rats. Fasting does not cause human muscles to use more fat and less sugar. Fasting uses up the sugar that was already in the muscle.
A more recent paper from Loma Linda University in California showed that athletes who fasted could exercise only half as long and required far more oxygen than those who ate before exercising. Fasting for 24 hours used up the same amount of muscle sugar as running for 90 minutes.
Dr. Mirkin is a practicing physician in Silver Spring specializing in sports medicine and nutrition.