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Dieting should include exercise

Question: I understand that people who lose weight don't usually keep it off for very long. What's the average length of time that most people maintain their weight loss?

Answer: About three years for keeping weight off as a result of dieting, according to the National Institute of Health panel of medical experts convened last year to examine methods of weight loss and control.

The panel also found, to no one's surprise, that the most common method of losing weight is dieting. In the surveys they reviewed, 80 percent of women and 75 percent of men reported trying to slim down by dieting alone. But the most effective way of losing weight, the experts said, is a combination of diet, exercise and patience. That is, although fewer pounds are lost with exercise/diet programs compared to diet alone, those who exercise, and accept modest weight-loss goals over an extended period of time, increase their chances of maintaining the weight loss. Of course, it's important to remember that when you exercise you gain muscle mass _ and muscle is heavier than fat. This often accounts for the weight loss differences between diet/exercise and diet-alone programs.

Irradiation facts

Question: Recently I ate some irradiated strawberries, and they tasted great. I know there's a great deal of controversy about irradiation, but I'm not sure what it's all about. Can you please provide me with some information about the process and any health hazards.

Answer: Food that's irradiated is bombarded with gamma rays that kill disease-causing bacteria. The process also extends the shelf life of fruits and vegetables by delaying ripening and sprouting. Irradiation is not new.

It has been used for years to sterilize medical supplies, tampons and condoms as well as to sanitize imported spices. (Spices are often sun-dried before shipment, exposing them to contamination by insects, birds, rodents and micro-organisms.)

However, irradiation is just beginning to be used more widely in food products.

And it's controversial. Here are the major arguments on both sides of the issue.

Opponents: Irradiation creates new and hazardous chemicals in the food, such as benzene and formaldehyde. The process alters the growth and reproduction of the tissue being zapped, so eating treated food may have the same effect on us and cause cancer. Irradiation destroys food nutrients and makes the food radioactive. The safety of the nuclear facilities used are unproven, and the transporting of radioactive material is unsafe.

Proponents: Irradiation is needed to reduce the nation's yearly tally of 6.5-million cases of food-borne illness and 7,000 related deaths.

The chemicals produced by irradiation are minute. Moreover, traces of these compounds are found naturally in foods and are created during pasteurization, canning and freezing and even when food is digested and metabolized. There's no evidence that eating irradiated food causes cancer or is in any other way harmful.

Nutrients remain virtually unchanged or are decreased no more than during cooking or other processing methods. Irradiation doesn't make food radioactive, since the gamma rays just pass through the products. Plants and transportation are safe.

When all is said and done, it looks as if irradiation is here to stay, along with fluoridation and the microwave oven, both also strongly opposed when introduced. The Food and Drug Administration now permits irradiation of wheat, potatoes, pork, spices, fruits and vegetables. And there are now 38 U.S. irradiation facilities with more being planned.

Write with questions to Dr. Patrick J. Bird, Dean of the College of Health and Human Performance, University of Florida, Gainesville, FL 32611.