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HLT 111 - Health and the Young Child - Textbook

Chapter 10: Nutrients that Provide Energy (Carbohydrates, Fats, and Proteins)

Chapter objectives

At the conclusion of this chapter students will be able to

  1. Identify the three major nutrient groups and their energy contributions
  2. Define the concepts of basal metabolic rate
  3.  Describe the relationship between amount of energy consumed and body weight.
  4. Describe simple sugars and complex carbohydrates as sources of energy
  5. Describe proteins as energy source; explain complete and incomplete proteins
  6. Describe unsaturated, monosaturated and poly saturated fats as sources of energy.



Carbohydrates are one of the six major nutrients and the main source of energy. Examples of carbohydrates include sugars, starch, and fiber in the diet. The body’s top priority is to provide enough energy for all cellular activities needed to sustain life. Carbohydrates are the preferred source of energy. If the diet does not provide adequate carbohydrates the body will draw mainly upon proteins for its energy needs.

By eating  adequate amounts of carbohydrates, proteins will be spared to be used for growth, development and regulatory functions of the body. If the diet is too low in carbohydrates, the body cannot break down fats completely, and incomplete fat break down products called ketones are produced and this may lead to Ketosis, a condition frequently encountered in diabetes mellitus, though in this case the cause is failure of the body to utilize carbohydrates rather that inadequate intake.

Fibers are carbohydrates which provide bulk in the diet. Fiber also helps to promote normal digestion and elimination of waste materials. Fibers also provide a feeling fullness by slowing the rate at which the stomach empties.

When the body does not make enough insulin or fails to use insulin correctly, glucose builds up in the bloodstream, a condition called diabetes mellitus. Another condition related to carbohydrate metabolism is called lactose intolerance.  This condition is caused by a lack of the digestive enzyme lactase, which is needed to break down lactose.  People who are lactose intolerant may experience gas, cramping, nausea and diarrhea when they consume dairy products.


Protein is an energy-yielding nutrient composed of carbon, hydrogen, oxygen, and nitrogen.

Proteins differs from carbohydrates and fats because of the presence of nitrogen. They are the  building blocks of all protein molecules are amino acids.  Protein is vital to the optimal growth and development of kids. Proteins account for 50% of the dry weight of the human body. Unlike lipids and carbohydrates, proteins are not stored, so they must be consumed daily. Current recommended daily intake for adults is 0.8 grams of protein per kg of body weight (more is needed for children).

The quality of a protein is determined by its ability to provide the 9 essential amino acids.  Proteins from animal sources (eggs, dairy, meat, poultry, and fish) and one vegetable protein (soy) are all considered high-quality because they contain all of the essential amino acids in the necessary proportions. The function proteins includes,

  • Maintain acid-base balance
  • Maintenance of the correct level of acidity of a body fluid
  • Proteins in the blood act as chemical buffers (counteract an excess of acid or base in a fluid)
  • Carry vital substances
  • Transport lipoproteins (protein linked with fat), iron, and other nutrients, as well as oxygen, chromosomes, and other bundles of protein to other parts of cells
  • Provide energy
  • Provides the cells with the energy they need to exist

If carbs and fats are lacking, the body uses protein as an energy source


Fats are made of carbon, hydrogen, and oxygen. Fats supply your body with energy, form your cells, maintain body temperature, and protect your nerves.  A nutrient that provides energy and helps the body store and use vitamins is a fatUnsaturated Fats have at least one unsaturated bond in a place where hydrogen can be added to the molecule. Unsaturated fats are usually liquid at room temperature (corn oil, soybean oil, peanut oil).

Unsaturated fats are classified as either monounsaturated fats or polyunsaturated fats. Fats that have all the hydrogen the carbon atoms can hold are called saturated fats. Saturated fats are usually solid at room temperature (butter, ghee, lard, margarine).

Too much saturated fat in your diet can lead to heart disease. Nutritionists recommend that 20-35% of your calories come from fat, primarily unsaturated fat.

Chapter Review and Discussion Questions


Chapter Review

  1. Identify three major nutrient groups that provide energy
  2. List the energy contribution per unit of the three major nutrient groups.
  3. Describe the recommended proportion of each of the three major nutrients in a diet.
  4. Describe the concept of basal metabolic rate.
  5. Describe the concept of thermic energy of food
  6. Describe simple and complex carbohydrates
  7. Describe unsaturated, monounsaturated and unsaturated fats
  8. Describe the concepts of complementary and supplementary proteins
  9. Give examples of complete and incomplete proteins
  10. Why are proteins an insufficient source of energy?