The keys to healthy eating are balance, variety and moderation. That's the message Dr. Margo Denke, assistant professor of internal medicine, shared with 80 members of the Friends of the Center for Human Nutrition at a fall luncheon.

"A balanced diet means it has the appropriate proportion of the macronutrients in the diet, the major sources of calories--carbohydrates, proteins and fat," said Dr. Denke. But a proper diet should also include a variety of foods to ensure a person gets all the nutrients needed for good health. A recent survey by the Department of Agriculture showed that most women do not get enough vitamin A, calcium or vitamin E, Dr. Denke said. How much a person needs of various nutrients continues to be the focus of intense research, Dr. Denke added. "Research quantifying how much we need of certain vitamins and minerals is sorely lacking. This area is at the forefront of nutrition," she said. Researchers at the Center for Human Nutrition are currently investigating vitamins and their potential for preventing coronary heart disease, the No 1. cause of death and disability in the country.

A balanced, varied diet can still cause problems if a person overeats, said Dr. Denke. Moderation is particularly important for women when eating at a restaurant, since many food establishment dole out ample portions gauged specifically for men. "The portion sizes are going to be a third to a half more than what we require to maintain our weight. We have to watch the portion sizes and amount of calories we consume," she said. The number of calories a person needs a day depends on his or her weight, the amount of energy expended to carry that weight and the person's physical activity level. "If you weigh more, you actually require more calories to walk, sit or stand than if you're leaner, " Dr. Denke said.

Women need fewer calories than men. A 140-pound man who has a low level of activity can take almost 2,000 calories a day, compared to 1,500 calories for a 140-pound woman, Dr. Denke said. In addition, older and sedentary people need fewer calories than the young or the physically active. If you are overweight, do not try to lose weight too fast, Dr. Denke recommended. A steady loss of ½ to 1 pound a week until you reach your goal is generally safe. To lose 1 pound a week, a person must subtract 500 calories a day--by eating less and/or by expending those calories through physical activity.

Exercise is a key component of maintaining proper calorie balance, Dr. Denke said. Through light activities such as house cleaning, gardening, golfing or car washing, men use up to 300 calories per hour and women use 240 calories per hour. In moderate activity such as tennis doubles or brisk walking, men expend around 460 calories per hour and women, 370 calories per hour. High activity, such as jogging or swimming, can burn up 730 calories an hour for men and 580 calories an hour for women.

"It is important to choose an exercise program that is enjoyable to you. Choose specific physical activities that are fun and in addition, help you maintain your weight, " Dr. Denke said. A diet low in fat makes it easier to include the variety of foods you need for nutrients without exceeding your calorie needs, Dr. Denke said. The total fat in a person's diet should provide no more than 30 percent of his or her total calorie needs. For example, at 1,500 calories per day, the suggested upper limit is 500 calories from fat. Since each gram of fat contains 9 calories, this equals 55.5 grams of fat. No more than 10 percent of total calories, or 17 grams in this instance, should come from saturated fat. "I can take that number and go to a food label and ask how many grams of fat is in this product and how much this product will contribute to my daily fat allotment," Dr. said.

The total carbohydrates in a person's diet should provide 55 percent of his or her total calorie needs, compared to 30 percent from fat and 15 percent from protein, Dr. Denke said. "We're allowed a lot more carbohydrates. So our diet should be enriched with fruits, vegetables and grains because these are the sources of carbohydrates," she said.

Dr. Denke advised that any fad or commercial diet plan should be approached with caution. "It's important to understand your own self and your underlying motivation that makes a fad diet attractive. While it is important to pick something that can work for you, there should be balance, variety and moderation in any diet plan," she said. A healthy diet has been linked to the prevention of numerous diseases, Dr. Denke said. Nutritionist are currently investigating the impact of a person's diet has on preventing coronary heart disease, osteoporosis, cancer, obesity, hyperactivity in children, kidney stones and kidney failure.