Nutrition - Spotlight on Nutrition
Americans are obsessed with thinness. 52% of Americans who have dieted or are dieting do so to feel better about how they look; only 16% say they diet for good health and well being. For most people, “dieting” means removing or reducing various foods.
We all need to eat to stay alive. Malnutrition (either too much food or not enough) can cause abnormal body function and disease. Sometimes, even though our eating habits are good, symptoms of diseases of malnutrition develop because we cannot digest or absorb foods properly. Such diseases may not be corrected by dietary changes alone and may need additional medical treatment.
All elements needed to sustain life come from the earth and the energy from the sun through the plants we consume. Since animals (non-human) also consume plants, they become a nutritional source when we consume animal products.
The Recommended Dietary Allowances
No one food has all of the nutrients we need. Recommended dietary allowances (RDAs) have been created based on what foods we need for optimal health. The foods that satisfy the RDAs fall into four groups: (1) dairy; (2) meat/fish/poultry; (3) grains; and (4) fruits/vegetables.
These groups make up the food pyramid, http://www.mypyramid.gov, which shows the kinds of foods and number of servings we all need to be healthy. The food pyramid also recommends that our daily diets should contain: 55% carbohydrate, 15% protein, and 30% fat (20% unsaturated). These essential dietary nutrients, as well as vitamins and minerals, are directly connected to good health.
Carbohydrates provide a source of energy. One such carbohydrate, glucose, can be stored in muscle and liver and used as a quick source of energy when needed. Carbohydrates also provide fiber (bulk) necessary to help movement of the intestines. Carbohydrates such as whole grain breads, pasta, fruits and vegetables are also rich in vitamins, minerals, and even some protein. Fruits and vegetables are low in calories because of their high water content (up to 90%) and are a good source of fiber, complex carbohydrates, protein, and a healthy assortment of vitamins and minerals. Fruits and vegetables provide virtually all of the vitamin C we need.
Proteins are important because they are needed for our body structures (hair, bone, skin, muscle), hormones (growth, insulin, pituitary), protection (antibodies, blood clotting) and make up our genes. Eating more protein beyond the recommended 15% of total calories, however, will not increase muscle size or body strength - only exercise can do that. Food products that are high in protein include animal and dairy products, and legumes (beans, peas, lentils, peanuts). Legumes are an incomplete protein source because they lack one or two essential amino acids but if you combine whole grains, dairy products, eggs, poultry, fish and meat, that will correct this problem. Strict vegetarian diets are limited and if not consumed in adequate varieties can lead to deficiencies in vitamins B12 and D, iron, calcium, iodide and zinc.
Fat is a storage form of energy that is used for long periods of muscle activity (work, exercise). Fat provides twice as much energy than protein or carbohydrate. There are different kinds of fats: complex lipids, steroids, and prostaglandins. They are grouped as saturated (solid at room temperature), or unsaturated (liquid at room temperature). The most abundant steroid in the body is called cholesterol. Cholesterol is carried in the blood as a high-density lipoprotein (HDL or “good cholesterol”), or a low-density lipoprotein (LDL ?not good?). Because high blood levels of LDL cholesterol have been linked to heart disease, many people think of cholesterol as a “bad guy.”
Actually, cholesterol is so important to life that our liver synthesizes (or makes) it to ensure an adequate blood level. Fats are needed for fat-soluble vitamins (A,D,E,K), and to make you feel full. Saturated fats are found in meat, poultry, milk, and shellfish; polyunsaturated fats are found in vegetable oils (corn, safflower, and fish oils) and mono-unsaturated fats are found in olive and peanut oils. When reading package food labels, be aware that “cholesterol free” and “hydrogenated” mean the fats are in the form of man-made “trans-fatty acids” which are quickly converted into “bad” cholesterol.
How much should I eat?
The energy (calories) we get from food must equal the energy we use. This can vary according to our body size, physical activity level, and other factors such as age, sex, family history, and current health status (growth, pregnancy, illness, etc.). To find out how many calories you need to eat each day to stay at your present weight, there are several mathematical formulas or reference tables that compare lean body mass and physical activity. One quick method is based on the idea that 13.5 calories/per pound of body weight are used by an inactive person (15 calories/lb. if moderately active; and 16.5 cals/lb for very active). So, a 200 lb. person who isn’t very active would need 2,700 calories per day to remain at 200 pounds. A very active 200-lb. person (like an athlete) would need 3,300 calories per day.
A healthy body mass and composition is a sign of a healthful diet and the amount of calories you need should be based on an ideal weight. A simple method to estimate what your ideal weight is:
For Females: 100 lbs. for 5 feet of height 5 lbs. for each additional inch
If you are not currently at your ideal weight, you can determine how many calories you need to get to your ideal weight. Take the ideal weight calculated above and multiply by 15. A 200 lb. person who wants to be 150 lbs., should eat 2,250 calories per day (150 x 15). You would need to adjust your eating to no more than 2,250 calories. Whatever the goal, keep in mind that you should not lose more than two pounds per week.
How should I eat?
Once you know how many calories to eat, make sure the calories are equally distributed in six small meals throughout the day. The three meals per day concept is not based on health recommendations but on a working force (breakfast at home, lunch on the job, and dinner at home). By having fewer calories at each meal, your body is able to use up calories without leaving excess in storage (fat). For these smaller meals, try using a saucer instead of a dinner plate, only one serving of food can fit on a saucer. Another hint: a portion of meat (4 oz) is approximately the size of your palm.
Nutrition, exercise and weight maintenance
A healthy diet and exercise will help you control your weight and lower the risk of serious health problems. Since good health depends on many different kinds of nutrients, the best diet must meet all the dietary requirements needed to sustain life, maintain body weight, and prevent illnesses that can be caused by poor eating habits.
Exercise is just as important as nutrition to maintain good health. Regular physical activity - such as a brisk walk for 30 minutes, five times per week - is inexpensive and readily available. Exercise will increase muscle tone and mass, burn calories, boost energy, lower “bad” cholesterol, relieve stress, prevent bone loss, lower the risk of heart disease, high blood pressure, diabetes, and even some cancers.
So, eat sensibly, take a walk, and enjoy good health!
Domenic A. De Bias, PhD, (1925-2006) was a Fellow of the College of Physicians of Philadelphia; Professor Emeritus at Philadelphia College of Osteopathic Medicine and an adjunct professor in the Pennsylvania State University-Frankford Hospital School of Nursing Program