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Food and Nutrients

Explains why the body needs food and nutrients.

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What happens when you don't eat?

Refusing one meal won't stunt your growth. But lack of proper food over a period of time can lead to malnutrition. That means, the body is not getting enough nutrients to grow and stay healthy. Kids who are malnourished may not grow as tall as they would otherwise.

Why We Need Food

Did you ever hear the old saying, “An apple a day keeps the doctor away”? Do apples really prevent you from getting sick? Probably not, but eating apples and other fresh fruits can help keep you healthy. The girls pictured below are eating salads (Figure below). Why do you need foods like these for good health? What role does food play in the body?

These girls are eating leafy green vegetables. Fresh vegetables such as these are excellent food choices for good health.

Your body needs food for three reasons:

  1. Food gives your body energy. You need energy for everything you do. Remember that cellular respiration converts the glucose in the food you eat into ATP, or cellular energy.
  2. Food provides building materials for your body. Your body needs building materials so it can grow and repair itself.
  3. Food contains substances that help control body processes. Your body processes must be kept in balance for good health.

For all these reasons, you must have a regular supply of nutrients. Nutrients are chemicals in food that your body needs. There are five types of nutrients:

  1. Carbohydrates.
  2. Proteins.
  3. Lipids.
  4. Vitamins.
  5. Minerals.

Carbohydrates, proteins, and lipids are categories of organic compounds. They give your body energy, though carbohydrates are the main source of energy. Proteins provide building materials, such as amino acids to build your own proteins. Proteins, vitamins, and minerals also help control body processes.


  • ATP (adenosine triphosphate): Usable form of energy inside the cell.
  • carbohydrate: Organic compound such as sugar and starch that provides an energy source for animals.
  • cellular respiration: Process of breaking down glucose to obtain energy in the form of ATP.
  • lipid: Organic compound that is insoluble in water and includes fats, oils, and waxes.
  • mineral: Chemical element, such as calcium or potassium, that is needed for body processes.
  • nutrient: Chemical in food that your body needs.
  • protein: Organic compound composed of amino acids and includes enzymes, antibodies, and muscle fibers.
  • vitamin: Organic compound needed in small amounts for the body to function properly.


  • Your body needs food to obtain energy, to get building blocks for your body, and to get substances that help control body processes.
  • Nutrients, chemicals in food that your body needs, include carbohydrates, proteins, lipids, vitamins, and minerals.


Use the resource below to answer the questions that follow.

  1. What do organisms use "food" for?
  2. What is a heterotroph? Are humans autotrophic or heterotrophic?
  3. What are the three types of heterotrophic organisms?


  1. Why does your body need food?
  2. What are nutrients?

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