The Medical Minute: Eating 101

April 07, 2009

By John Messmer

Practicing physicians hear familiar remarks about people’s diets. Common misunderstandings include:

  • Substituting chicken for beef makes a diet healthy.
  • Supplements are a substitute for fruits and vegetables.
  • Eating only one meal a day is a good way to cut down.
  • Not eating after 6 p.m. is a good idea.
  • If I am hungry, I must eat something or I’ll become weak.
  • Healthy eating at a restaurant is impossible.
  • Healthy eating means giving up ethnic or heritage foods.
  • It takes a lot of time to prepare healthy foods.

Something all of us do daily, like eating, should not require a nutrition degree to do correctly, and it doesn’t. Food is necessary for life, but it can be fun, too. Done properly with a bit of planning, food will make us feel good, feed our appetites and improve our health and energy levels.

Does this mean we must give up French fries, onion rings, cake and ice cream? Not entirely, but these high fat, entertainment foods are a big problem if they are more than a tiny part of our overall diets. Eat well most of the time, and an occasional splurge will not be a problem as long as you don’t need to lose weight. Extra calories get in the way of weight loss.

Our bodies need three basic dietary components: carbohydrates, proteins and fats. Fiber, vitamins, minerals and trace nutrients will be included in sufficient quantities if the three basic components are chosen properly.

Let’s consider carbohydrates first. This group has been given a bad reputation in popular weight-loss programs, but the truth is we need carbohydrates for energy. All carbohydrates are composed of sugar, either plain sugar or sugar molecules joined together. The ones that break down quickly — referred to as having a high-glycemic index — raise blood sugar levels fast, contribute to obesity and can make diabetes harder to control. The carbs that break down slowly — said to have a low-glycemic index — are preferred since our bodies can use the energy and we feel as though we have had enough to eat without overdoing it.

We should eat less of the high-glycemic carbohydrates, which include pastas, white flour, white rice, white bread, potatoes, corn, pretzels, cookies, cake, bagels and low-fiber cereals and sugars. A teaspoon or two of sugar in coffee is fine. Problem sugars include regular soda, candy, syrups, honey, molasses and fruit juices, including orange juice, grapefruit juice and others.

Instead, we should eat low-glycemic carbohydrates including grains such as brown rice, quinoa, barley and whole wheat; beans, lentils and other legumes; crunchy fruits such as apples, melons, berries and most vegetables, including sweet potatoes or yams. The added benefit from this group is fiber — the indigestible part of the food that helps slow absorption and contributes to intestinal health.

To obtain the full complement of essential nutrients, choose a variety of colors of fruits and vegetables throughout the week. The average person should have 5-8 servings of fruits and vegetables daily. To determine how much you should have, go to the Center for Disease Control’s Fruit and Veggies Matter Web page at

Protein is found in meat, fish, milk and many plant sources. A 3-ounce serving, about the size of a deck of cards, of lean meat (lean beef or pork, chicken or turkey) is fine. Fatty meats, such as ribs, should be eaten sparingly (pardon the pun). Organ meats (liver, kidney, brain, sweetbreads and chitterlings) are so high in fat they should either be avoided or included only rarely. Breakfast meats such as bacon, sausage and scrapple should be limited as they are high in fat.
Fish is nutritious and a good alternative to meat. Swordfish, mackerel, shark and tilefish tend to accumulate mercury, so these should be eaten less than twice a month, and pregnant women should avoid them altogether. Fish has EPA and DHA, known as omega-3 fatty acids, a nutrient that reduces risks of heart disease.

Beans and other legumes such as lentils, soybeans and chickpeas are excellent sources of protein with almost no fat and should be included in our diets frequently. Those foods are also high in needed fiber. Although nuts and seeds have fat, they have high quality protein, and the fats are monounsaturated fats, which are good for us in modest quantities. Vegetarians and vegans in particular must be careful to include high quality vegetable protein in their diets.

Dairy products are not an essential component to the human diet, but dairy foods can provide good nutrition for those who can consume dairy. Dairy products have protein, plus they contain the richest source of calcium — a nutrient essential to bone strength, muscle and nerve function and blood clotting. Women in particular require lots of calcium to build strong bones, which are more resistant to thinning from osteoporosis after menopause.

Fats come in good and bad forms. Oils are liquid fats and are generally better for us than solid ones. Oils or “good fats” are found in nuts, seeds, some vegetables such as olives and avocados, and many fish. “Bad fats” tend to be solid. They are also called “saturated” fats based on their chemical structure having more hydrogen. Examples of saturated fats are animal fats, palm and coconut oils (tropical oils) and partially hydrogenated oils found in some processed foods. The latter are the “trans” fats that tend to clog arteries. All fats, good or bad, have more than twice the calories of other foods.

One more thing to consider is sodium. Many otherwise highly nutritious foods have sodium added. Prepared foods, such as, soups and frozen dinners, are major offenders and can fill the entire day’s allotment of sodium in one or two servings. All herbs and spices are fine, but sodium can lead to high blood pressure and stresses weak hearts.

There are cookbooks and recipes available on the internet, in bookstores and there is plenty of education through government websites, such as, and Even ethnic heritage foods can be made healthy. A search for the word “ethnic” at will show numerous links.

Choose vegetables and fruits as the foundation of your diet. Add high quality protein from plants or lean animal protein and some nuts and seeds. Keep sugar, alcohol and high glycemic foods to a minimum. Eat small portions throughout the day. Supplements are not necessary, but, if used, they are meant to supplement the diet, not substitute for it. For those in a hurry, there are healthy, well balanced frozen meals available now in most supermarkets. It’s more expensive than making it yourself but may be a solution for the busy person.

Healthy eating does not require an advanced degree, just some basic knowledge and a little planning.

John Messmer is associate professor of family and community medicine at Penn State College of Medicine and a staff physician at Penn State Hershey Medical Center.

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Last Updated July 22, 2015