Body Fat

Is all fat bad?
What's the best way to lose fat?

What is fat? Why is it good for you?
How does a fat cell function?

[Apple Image] Getting Started

Bring food labels to school representing as many of the five food groups as possible. Find the serving size and number of servings in each container or box. Since most fruits and vegetables do not come in containers, "guestimate" their size and check the serving size in a cookbook. Why is it important to know serving size? How does this information help in your daily menu planning?

Do you think you eat well? Why? Do you know anyone who has lost weight? How did they do it?

Do you pay attention to the nutritional value of the food you eat? Do you pay attention to how much fat is in your food? How does fat in your food relate to the fat in your body? Why is fat important to the human body? Why is too much fat bad?

[Apple Image] Overview

To supply the calories our bodies need for energy, we must eat food. As food passes through our digestive systems, it is mechanically and chemically broken down into nutrients (amino acids, simple sugars, fatty acids, and monoglycerides) that our bodies use for growth, maintenance, and repair. When these simplified nutrients -- especially the simple sugars and fats -- reach the cells, they are metabolized as fuel. This releases heat, which is measured in calories.

With calories, the body works on a supply-and-demand system. If the daily calorie supply from food you've eaten meets the daily demand, all the calories from fats, proteins, and carbohydrates are converted to energy. If the daily supply exceeds the demand, the excess calories are stored in fat cells. These fat cells serve as energy warehouses for fat molecules, allowing your body to draw upon the stored fat when your demand for calories exceeds the daily supply from the food you consume.

Despite the recent negative publicity about fatty foods, we all need some fat in our diets. It's a good source of the calories we require to fuel our bodies and to keep us going when our energy demands suddenly increase. One gram of fat provides nine calories of energy, while one gram of protein or carbohydrate offers only four. Fat also gives texture and flavor to foods. It helps us feel full and satisfied after we eat. In addition, it protects our organs, aids in the development of cell membranes and hormones, and insulates our bodies.

However, we should eat fat sparingly -- it should make up no more than 30 percent of our daily caloric intake. Excess fat in our bodies is linked to health problems such as hardening of the arteries and heart disease, to name just two.

Throughout a day, a month, a year, and even a lifetime, the body's supply of and demand for fat changes. Demand increases with activity and decreases in sedentary times. We can modify our caloric intake to meet these changing conditions. We can also manage the body' s fat supply through exercise, which uses fat as fuel. So, to maintain a healthy balance in our bodies, we need to monitor our food intake and energy demands and add a daily dose of exercise.

[Apple Image] Connections

  1. What part do calories and exercise play in our daily lives?
  2. What role does fat have in our diets? Where does it come from and go to?
  3. Why do we gain or lose weight?
  4. What would happen if we had no fat in our diets?
  5. What diseases are associated with excess fat intake?

[Apple Image] Resources

Are you eating right? (1992, Oct) Consumer Reports, pp. 644 - 655.

Lambourne, M. (1992) Down the hatch. Brookfield, CT: The Millbrook Press, Inc.

Munoz, W. (1992) Nutrition: What's in the food we eat? New York: Holiday House.

Choose a diet low in fat, saturated fat, and cholesterol:
http://www.nalusda.gov/fnic/dga/dga95/lowfat.html

Surgeon General's Report of Physical Activity and Health. For a copy, call (888) 232-4674, or request a summary sheet at:
http://www.cdc.gov

United States Department of Agriculture
Nutrient Data Laboratory
4700 River Rd
Riverdale, MD 20737
(301) 734-8491
Request Home and Garden Bulletin #72: Nutrient value of food.

Cooperative Extension Service: Fat facts
University of Illinois at Urbana-Champaign:
http://www.agen.ufl.edu/~foodsaf/il041.html

Student Activity:
Body Fat

Carrying Your Calories

Plan what you'd need to pack for a three-day hiking trip.

[Apple Image] Main Activity

Want to get away from it all? Go mountain hiking? Now's your opportunity. Plan a three-day backpacking trip to the Rocky Mountains in Colorado. Your trip will involve climbing, carrying, eating, cooking, and sleeping. All these activities will challenge your body's supply of and demand for calories. Plan what you'll pack for your trip as if your life depended on it.

Materials

1. As a class, discuss what items you should include in your gear. Write these on the chalkboard. Discuss how important each one is for a safe trip.

2. For this trip your gear is limited to 40 pounds (18 kilograms), of which 15 pounds (6.75 kilograms) can be food. Plan for your nonfood gear to weigh 25 pounds (11.25 kilograms).

3. Estimate how many calories you'll need to consume each day. Keep in mind that your activity level will be higher than normal during this three-day hike so you'll burn more calories than you do normally.

4. Knowing your total calorie needs, figure how you can meet your daily nutritional needs in each of the five USDA food groups. What percentage of your total daily calories should come from each group?

5. Next, think of foods you can carry that will meet both your caloric and nutritional needs for three days, yet allow you to remain within your food weight limit. Discuss your food list with your classmates and your family.

6. Gather your food choices and weigh them. Add or subtract items as necessary, keeping in mind your daily food needs as well as water consumption needs.

Questions

  1. What effect did vigorous activity have on your menu?
  2. Why did you choose the foods you chose? How close were you to your weight limit?
  3. How are you planning to meet your water needs?
  4. What percentage of the calories were from fat?
  5. What kinds of foods were light in weight but high in nutrition and calorie needs?

[Try This]

Go to your local grocery store and look for four or five products that have regular and light versions. An example would be yogurt. Read the labels of both the regular and light versions. How are they the same? How are they different? What ingredients are exchanged or lessened to get a light version? How do they compare in taste?

[Try This]

List all the things you usually order when you eat a meal at a fast-food restaurant. Do some research to find out what the calorie count is for each item. Add the total calories. If it exceeds 500 calories, what could you do to reduce the calories, but still eat the meal?

[Try This]

Fat is in almost everything you eat, especially those things that are on many people's "favorites" list,
like pizza, doughnuts, and potato chips. Your challenge is to plan a lunch or dinner meal with no fat.
Good luck!


Return to Daryl's Main Demo Page

Tapes of this episode of Newton's Apple and others are available from GPN for only $24.95.
Please call 1-800-228-4630.
For information on other Newton's Apple resources for home and school,
please call 1-800-588-NEWTON!


We encourage duplication for educational non-commercial use.
Educational materials developed with the National Science Teachers Association.
NEWTON'S APPLE is a production of KTCA Saint Paul/Minneapolis. Made possible by a grant from 3M.
PBS Online - Minnesota Online - Welcome to Newton's Apple - Teacher's Guides Index