Section 8.1 Carbohydrates, Fats, and Proteins
Carbohydrates, Fats, and Proteins
Objectives
Name the three classes of nutrients that supply
your body with energy.
Explain how the body obtains energy from
foods.
Describe the roles that carbohydrates, fats,
and proteins play in your body.
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Section 8.1 Carbohydrates, Fats, and Proteins
Video Introductorio
https://www.youtube.com/watch?v=cptGzi0wLiE
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Section 8.1 Carbohydrates, Fats, and Proteins
Nutrition
The sum of the processes by which humans, animals,
and plants consume and use food is nutrition.
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Section 8.1 Carbohydrates, Fats, and Proteins
Nutrients
Food is eaten and digested in the
body to allow the absorption of
energy and nutrients.
There are two different types of
nutrients:
macronutrients;
micronutrients.
There are three macronutrients
that are essential for health.
These are:
• carbohydrate;
• protein;
• fat.
Macronutrients are measured in
grams (g).
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Section 8.1 Carbohydrates, Fats, and Proteins
Foods Supply Nutrients
• Food supplies your body with nutrients, substances
in food that helps with body processes (regulate
bodily functions, promote growth, repair body
tissues, and obtain energy).
• There are six classes of nutrients: carbohydrates,
fats, proteins, vitamins, minerals, and water.
• Carbohydrates, fats, and proteins can all be used by
the body as sources of energy.
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Section 8.1 Carbohydrates, Fats, and Proteins
Foods Supply Energy
• The foods you eat are your body’s energy source.
• You need energy to maintain your body temperature,
keep your heart beating, and enable you to
understand what you read.
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Section 8.1 Carbohydrates, Fats, and Proteins
What are Calories?
• The amount of energy released when nutrients are
broken down is measured in units called calories.
• The more calories a food has, the more energy it
contains.
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Section 8.1 Carbohydrates, Fats, and Proteins
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Section 8.1 Carbohydrates, Fats, and Proteins
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Section 8.1 Carbohydrates, Fats, and Proteins
Carbohydrates
• Carbohydrates are nutrients made of carbon,
hydrogen, and oxygen.
• Carbohydrates supply energy for your body’s
functions.
• A nutrient that is the main source of energy for the
body is a carbohydrate.
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Section 8.1 Carbohydrates, Fats, and Proteins
Carbohydrate
The two types of carbohydrate that
provide dietary energy are starch
and sugars. Dietary fibre is also a
type of carbohydrate which is not
digested to provide energy.
Starchy carbohydrate is an
important source of energy.
1 gram of carbohydrate provides
4kcal (17kJ).
Section 8.1 Carbohydrates, Fats, and Proteins
Structure of carbohydrate
All types of carbohydrate are compounds
of carbon, hydrogen and oxygen.
They can be classified in many different
ways. One common way is according to
their structure.
Sugars
Sugars come from a variety of foods.
Some are within the cellular structure of
the food, e.g. in fruit or vegetables.
Other sugars are not bound into the
cellular structure of the food, e.g. in milk or
honey.
Section 8.1 Carbohydrates, Fats, and Proteins
Free sugars
Free sugars include all sugars added to foods
plus sugars naturally present in honey, syrups and
unsweetened fruit juice.
The term does not include lactose (the sugar in
milk) when naturally present in milk and dairy
products and the sugars contained within the
cellular structure of foods (e.g. fruit and
vegetables).
The recommendations state that less than 5% of
total energy intake should come from free
sugars.
For more information about free sugars, go to:
www.nutrition.org.uk
Section 8.1 Carbohydrates, Fats, and Proteins
Starchy carbohydrate
Starch is found in a variety of foods. It is made up of many
sugar molecules.
Can you give some examples of sources of starch in the diet?
•
•
•
•
Potatoes
Bread
Rice
Pasta
Cereal and cereal products are the main source of carbohydrate
for adults in the UK.
Section 8.1 Carbohydrates, Fats, and Proteins
Simple Carbohydrates
Simple carbohydrates are sugars that enter the
bloodstream rapidly and provide quick energy.
• Simple carbs provide calories but few vitamins
and minerals.
Complex Carbohydrates
Complex carbohydrates are made up of sugars that
are linked together chemically to form long chains.
•Starch – a food substance that is made and stored in
most plants
• Provide long-lasting energy
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Section 8.1 Carbohydrates, Fats, and Proteins
Carbohydrates can be…
Simple Carbs
Complex Carbs
- Fruits
- Honey
- Milk
- Sugars added to cookies,
candies, soft drinks
-Grains (bread & pasta)
-Vegetables (potatoes &
beans)
-Rice
-Cereals
-Wheat
-Tortillas
-Whole-wheat rolls
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Section 8.1 Carbohydrates, Fats, and Proteins
Fiber
• Fiber is a type of complex carbohydrate that is found
in plants.
• A high-fiber diet
• helps prevent constipation
• may reduce the risk of colon cancer
• may help prevent heart disease
• The part of grains and plant foods that cannot be
digested is called fiber.
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Section 8.1 Carbohydrates, Fats, and Proteins
Your Body’s Energy Reserves
• At a meal, you usually eat more carbohydrates than
your body can immediately use.
• The extra glucose is converted into a type of starch
called glycogen.
• Glycogen is stored in the muscles and when you
need energy, it is converted to glucose.
• If you eat so many carbohydrates that the body’s
glycogen stores are full, then the excess
carbohydrates are stored as fat instead.
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Section 8.1 Carbohydrates, Fats, and Proteins
Activity 1.
DRAW UP A COMPARATIVE
TABLE OF THE
CLASSIFICATION OF
CARBOHYDRATES
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Section 8.1 Carbohydrates, Fats, and Proteins
Fats
• 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 fat.
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Section 8.1 Carbohydrates, Fats, and Proteins
Fat
Fat provides fat-soluble vitamins A, D,
E and K, and is necessary for their
absorption. It is also important for
essential fatty acids the body cannot
make.
Fat provides a concentrated source of
energy:
1 gram of fat provides 9 kcal (37 kJ)
of energy.
Foods that contain a lot of fat provide
a lot of energy.
Section 8.1 Carbohydrates, Fats, and Proteins
Structure of fat
Fat is made up of different types of fatty acids and glycerol.
The structure of the fatty acids determines:
their effect on our health;
their characteristics, e.g. melting point.
Depending on their chemical structure, fatty acids are usually
classified as:
saturated;
monounsaturated;
polyunsaturated.
Section 8.1 Carbohydrates, Fats, and Proteins
Unsaturated Fats
• Unsaturated 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.
• Unsaturated fats are classified as either
monounsaturated fats or polyunsaturated fats.
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Section 8.1 Carbohydrates, Fats, and Proteins
Saturated Fats
• Fats that have all the hydrogen the carbon atoms
can hold are called saturated fats.
• Saturated fats are usually solid at room temperature.
• Too much saturated fat in your diet can lead to heart
disease.
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Section 8.1 Carbohydrates, Fats, and Proteins
Daily Fat Intake
Nutritionists recommend that 20-35% of your calories
come from fat, primarily unsaturated fat.
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Section 8.1 Carbohydrates, Fats, and Proteins
Cholesterol
• Cholesterol is a waxy, fatlike substance that is found
only in animal products.
• Your body needs a certain amount of cholesterol to
make cell membranes and nerve tissue, certain
hormones, and substances that aid in the digestion
of fat.
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Section 8.1 Carbohydrates, Fats, and Proteins
Trans Fats
• Trans fats are made when manufacturers add
hydrogen to the fat molecules in vegetable oils.
• Trans fats are found in margarine, chips, and
commercially baked goods.
• Trans fat seems to have many of the negatives of
saturated fat.
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Section 8.1 Carbohydrates, Fats, and Proteins
ACTIVITY 2
DRAW UP A
COMPARATIVE TABLE OF
THE CLASSIFICATION OF
FATS
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Section 8.1 Carbohydrates, Fats, and Proteins
Proteins
• Nutrients that contain nitrogen as well as carbon,
hydrogen, and oxygen are called proteins.
• Proteins can serve as a source of energy.
• A nutrient that is needed for growth, and to build and
repair body tissues is a protein.
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Section 8.1 Carbohydrates, Fats, and Proteins
Proteins
Protein functions include:
1. enzyme catalysts
2. defense
3. transport
4. support
5. motion
6. regulation
7. storage
Section 8.1 Carbohydrates, Fats, and Proteins
Protein
Protein is essential for growth and repair and keeping cells healthy.
Protein also provides energy:
1 gram of protein provides 4 kcal (17 kJ).
Section 8.1 Carbohydrates, Fats, and Proteins
Structure of protein
Protein is made up of building blocks
called amino acids. Different foods
contain different amounts and different
combinations of amino acids.
Protein from animal sources (e.g. meat,
fish, eggs and dairy products) contains
the full range of essential amino acids
needed by the body.
Protein from plant sources (e.g. pulses
and cereals) typically contain fewer
essential amino acids.
Section 8.1 Carbohydrates, Fats, and Proteins
Proteins
Proteins are polymers of amino acids.
Amino acids
-20 different amino acids
-joined by dehydration synthesis
-peptide bonds form between adjacent amino acids
Section 8.1 Carbohydrates, Fats, and Proteins
Proteins
Section 8.1 Carbohydrates, Fats, and Proteins
Proteins
Amino acid structure
-central carbon atom surrounded by
-amino group
-carboxyl group
-single hydrogen
-variable R group
Section 8.1 Carbohydrates, Fats, and Proteins
Proteins
Section 8.1 Carbohydrates, Fats, and Proteins
Proteins
Section 8.1 Carbohydrates, Fats, and Proteins
Sources of protein
Animal:
• meat;
• fish;
• eggs;
• milk;
• cheese.
Plant:
• nuts;
• seeds;
• pulses, e.g. beans, lentils;
• mycoprotein;
• soya products.
Section 8.1 Carbohydrates, Fats, and Proteins
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Section 8.1 Carbohydrates, Fats, and Proteins
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•4 Section 8.1 Carbohydrates, Fats, and Proteins
1
Proteins
Denaturation is a change in the shape of a protein,
usually causing loss of function.
-may involve complete unfolding
-caused by changes in the protein’s environment
-pH
-temperature
-salt concentration
Section 8.1 Carbohydrates, Fats, and Proteins
Amino Acids
• Proteins are long chains of smaller “links” that are
bound together chemically.
• These smaller substances are known as amino
acids.
• The building blocks that make up proteins are amino
acids.
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Section 8.1 Carbohydrates, Fats, and Proteins
Essential Amino Acids
The nine amino acids that the body cannot
manufacture are called essential amino acids.
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Section 8.1 Carbohydrates, Fats, and Proteins
Complete and Incomplete Proteins
• Protein from animal sources is complete protein.
• It contains all nine essential amino acids.
• Most protein from plant sources is incomplete
protein.
• It lacks one or more of the essential amino acids.
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Section 8.1 Carbohydrates, Fats, and Proteins
Daily Protein Intake
Nutritionists recommend that 10-35% percent of your
calories come from proteins.
Proteins for Vegetarians
People who don’t eat meat can combine two or more
plant protein sources that, taken together, provide all
the essential amino acids.
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Section 8.1 Carbohydrates, Fats, and Proteins
Activity 3.
DRAW UP A COMPARATIVE TABLE
OF THE CLASSIFICATION OF
PROTEINS
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Section 8.1 Carbohydrates, Fats, and Proteins
Vocabulary
nutrient
A substance in foods that the body needs to
regulate bodily functions, promote growth, repair
body tissues, and obtain energy.
metabolism
The chemical process by which the body breaks
down food to release energy.
calorie
Unit for the amount of energy released when
nutrients are broken down.
carbohydrate
A nutrient made of carbon, hydrogen, and
oxygen and that supplies energy.
fiber
A way of dealing with an uncomfortable or
unbearable feeling or situation.
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Section 8.1 Carbohydrates, Fats, and Proteins
Vocabulary
fat
unsaturated fat
saturated fat
cholesterol
A nutrient made of carbon, hydrogen, and
oxygen; supplies energy, forms cells, maintains
body temperature, and protects nerves.
A fat with at least one unsaturated bond in a
place where hydrogen can be added to the
molecule.
A fat that has all the hydrogen the carbon atoms
can hold. A fat that has all the hydrogen the
carbon atoms can hold.
A waxy, fatlike substance that is found only in
animal products.
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Section 8.1 Carbohydrates, Fats, and Proteins
Vocabulary
trans fat
The type of fat produced when manufacturers
add hydrogen to the fat molecules in vegetable
oils.
protein
A nutrient that contains nitrogen as well as
carbon, hydrogen, and oxygen; needed for the
growth and repair of body tissues.
amino acid
Small units that are bound together
chemically to form proteins.
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Section 8.1 Carbohydrates, Fats, and Proteins
Questions
1)
2)
3)
4)
5)
6)
7)
Which 3 classes of nutrients supply the body with energy?
Define the term metabolism. How is metabolism related to the
nutrients in food?
What roles do the following nutrients play in the body? A.
carbohydrates B. fats C. proteins
What is cholesterol? How does diet affect cholesterol levels in the
blood?
Name a circumstance during which you might use your body’s
stores of glycogen.
How do saturated fats differ from unsaturated fats? Name 2
sources of each type of fat.
Suppose that you ate 2,500 calories/day. Of those calories, 1,200
calories were from carbs, 875 from fats, and the rest from protein.
What % of your total day’s calories came from carbs, from fats,
and from protein?
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