Rebuilding the Food Pyramid
by Jeanne Miller
If you're trying to figure out the healthiest way to eat, you may be feeling confused by the conflicting messages you've been hearing. Should you avoid fat and fill up on carbohydrates like bread, rice, and pasta, as the existing food pyramid advises? Should you avoid carbohydrates and eat mostly protein foods like meat, eggs, and cheese—no need to worry about fats—as some popular weight-loss diets recommend?
The U.S. Department of Agriculture (USDA) introduced its Food Guide Pyramid a dozen years ago to teach the public about nutrition. Its low-fat, high-carbohydrate message has done nothing to slow the steady increase in obesity in the United States that has so alarmed public health officials.
USDA Food Guide Pyramid
- Bread, Cereal, Rice & Pasta Group: 6—11 Servings
- Vegetable Group: 3—5 Servings
- Fruit Group: 2—4 Servings
- Milk, Yogurt & Cheese Group: 2—3 Servings
- Meat, Poultry, Fish, Dry Beans, Eggs & Nuts Group: 2—3 Servings
- Fats, Oils, & Sweets: Use Sparingly
A New Emphasis
At the Harvard School of Public Health, researchers say that the USDA's Food Guide Pyramid is outdated and fails to give us enough information to help us make wise choices. Good nutrition is not just a question of fat vs. carbohydrates. The researchers have taken apart the pyramid, block by block, and have built a new one in its place.
Harvard's Healthy Eating Pyramid reflects recent research into human nutrition and its effect on health. The Harvard structure rests on a base of daily exercise and weight control. Exercise is a key element of health. It's good for every system in our body. Another essential ingredient of health is staying at the right weight for your height. Consult your doctor or school nurse to find out what your healthy weight range is.
Harvard's Healthy Eating Pyramid
Good Fat and Bad Fat
At the very top of the USDA's Food Guide Pyramid, in the “Use Sparingly” category, are all fats and oils. Dr. Lilian Cheung, of the Harvard University Department of Nutrition, points out, “It implies that all fats are bad. There are some good fats.”
There are big differences among saturated fats, trans-fats, and unsaturated fats. Saturated animal fats—those that are solid at room temperature (picture butter, lard, or the cooled fat left behind when beef is cooked)—are bad fats. They can clog arteries and lead to heart disease, stroke, and other problems. The food industry has created another kind of fat—trans-fat—by bubbling hydrogen through vegetable oil. This process, called hydrogenation, produces a solid fat that takes a long time to spoil. Manufacturers prize it for cookies, crackers, packaged snacks, and many other items that travel from factories to distant supermarket shelves. Fast-food restaurants use this hydrogenated vegetable fat for frying. Trans-fat, say the scientists at Harvard, is even more harmful to us than natural saturated fat.
Unsaturated fats, on the other hand, are good for your heart. These are the fats in most vegetable oils, nuts, seeds, whole grains, and fish. Because of the health benefits of eating plant oils, the Harvard School of Public Health puts them close to the base of its structure, for daily consumption. Saturated fats, like those in red meat and butter, are at the very top, in the “Use Sparingly” category.
How Refined Is That Carbohydrate?
According to Dr. Cheung, the second big problem with the USDA Food Guide Pyramid is that it encourages eating up to 11 servings a day from the bread, cereal, rice, and pasta group at its base. “But it doesn't distinguish between whole grains and refined carbohydrates,” she says. “And biologically, refined carbohydrates act similar to sugar.”
Refining carbohydrates strips them of nutrients and fiber. In the course of turning wheat into white flour, mills crush the wheat grain and separate the starchy center from the oil- and vitamin-rich sprouting section (the germ) and from the fiber- and mineral-rich outer coat (the bran). What's left is nutritionally deficient carbohydrate powder. This white flour is the main ingredient of most bread, crackers, and pasta. White rice and the grains in many breakfast cereals have also lost their germ and their bran. Though manufacturers may add back some of the lost vitamins and minerals, the nutrient profile of the refined grain will never match that of the original.
Your digestive system quickly turns refined grain into the simple sugars it uses for fuel. If there's no immediate need for that fuel, your body rushes to remove these extra sugars from the bloodstream and store them in your cells for later use. This can leave the blood sugar level temporarily low, causing you to feel hungry. If you take this cue to eat again, you may easily overwhelm your body's carbohydrate storage capacity, and the remaining carbohydrates will be stored as fat. By contrast, whole grains break down slowly, increasing the blood sugar gradually.
The carbohydrates in fruits and vegetables exist in combination with fiber, which slows their digestion and avoids the blood-sugar roller coaster. In addition to vitamins and minerals, they contain phytochemicals, beneficial compounds that scientists have only begun to discover and categorize. Many of these phytonutrients are the ones that give color to the fruit or vegetable, so eating deeply colored plant products offers much more than eye appeal. The Harvard plan recommends eating vegetables in abundance and fruit two to three times a day. (Too quickly digested, potatoes are an exception to this rule, so the Harvard eating guide groups them with refined grains and sugar.)
Not All Protein Is Created Equal
The third big problem with the Food Guide Pyramid is in the protein category. Dr. Cheung says, “It lumps meat, eggs, nuts, and legumes all together. But, although they are all rich sources of protein, biologically they are different. We know that fatty meats—especially fatty red meats and processed meats—are not so healthy. They increase the risk of heart disease and cancer. But the kind of fat in fish and nuts and legumes actually protects against heart disease.”
The Harvard guide puts nuts and legumes (peas and beans, including soy products) just above fruits and vegetables. Above those are other protein foods, such as fish, poultry, eggs, and non-fat or low-fat dairy products. Because of their saturated fat content, high-fat cuts of red meats (beef, pork, lamb) should not be a regular part of your diet.
What Should You Eat?
“The whole idea is to limit sugar, limit trans-fats, limit refined grains, and have plenty of fruits and vegetables in rainbow colors,” Dr. Cheung says. “Look for products that are less refined, less manufactured, less processed. It's always better to have it fresh and whole.” Her hope is that an educated younger generation can turn around this country's epidemic of obesity and eating-related diseases. Adopting the principles of the Harvard Healthy Eating Pyramid could be a major step in the right direction.
To complete this activity, you will need to print out the worksheet titled “Food Pyramids” (PDF file).
- What are the differences between the USDA Food Guide Pyramid and Harvard's Healthy Eating Pyramid?
[anno: The USDA pyramid does not make a distinction between good fats and bad fats, but the Harvard pyramid does. The USDA pyramid does not make a distinction between different kinds of grains, meat, and dairy products the way the Harvard pyramid does.]
- Print out the worksheet titled “Food Pyramids.” Write down everything you eat for one day in each of the pyramids. Study the pyramids after you have filled in the foods. Are there differences between how balanced your diet is when you look at the foods you listed in the USDA pyramid versus the Harvard pyramid? Write a few sentences that describe how your diet is different depending on which pyramid you use.
[anno: Worksheets will vary but should include the student's food intake for one day. Food intake should be plotted in the USDA pyramid and then in the Harvard pyramid. Sentences should describe how well balanced the student's diet is on the USDA pyramid versus the Harvard pyramid.]