1. Food and nutrition
Section 30.2

2. Why shouldn’t you eat this every day?

3. Why do humans need to eat?
For Energy!
Food contains the basic molecules that can be use to build ATP
Food supplies the raw materials your body needs to build and repair tissues
Food contains at least 45 substances that the body needs, but does not manufacture
A healthy diet ensures that your body receives all of these required substances

4. How do you measure the amount of energy in food?
You burn it
One calorie is the amount of heat needed to raise the temperature of 1 gram of water by 1 degree Celsius
One dietary Calorie is equal to calories, or 1 Kilocalorie

5. What nutrients does your body need?
Water
Carbohydrates
Fats
Proteins
Vitamins
Minerals

6. Why is water important?
Every cell needs water, because many of the body’s chemical reactions take place in water
Water makes up blood, extracellular fluid and other bodily fluids
We loose water as sweat, urine or when we breathe
Humans on average need to drink at least 1 liter of water a day to replace what is lost
In Arizona we need to drink a lot more than this – why?
If the body does not get enough water, it can lead to dehydration, which under certain conditions can be fatal

7. Why do you need to eat Carbohydrates?
Simple and complex carbohydrates are a major source of energy
Sugars found in fruits, honey and sugar cane are simple carbohydrates
Starches found in grains, potatoes and vegetables of complex carbohydrate, or polysaccharides
The digestive system breaks down starch into simple sugars
Excess blood sugar is converted into glycogen, which is stored in the liver and skeletal muscles
Excess sugar can also be stored as body fat
Fiber is also a type of complex carbohydrate – cellulose? Why is Fiber important?
Our bodies can not break down fiber, but it’s presence help move things along the digestive system

8. Is it always bad to eat Fat?
Not always - Fats help the body absorb fat soluble vitamins, and are a part of cell membranes, nerve cells and certain hormones
What is the structure of a fat? What is the difference between a saturated and an unsaturated fat?
Many unsaturated fats are modified by adding hydrogen to them – trans fats
This increases the shelf life, but may have some serious health related side effects

9. Why do many people who work out with weights eat protein bars/drink protein shakes?
Proteins supply the raw materials for growth and repair of structures such as skin and muscle
Many enzymes are proteins – why are enzymes important?
What role do proteins have in transport across cell membranes?
Hormones can be protein - such as insulin
Hemoglobin is a protein – what does this protein do?
Proteins can even be used as an energy source when others are in short supply
What are proteins made of?
Only 12 of the 20 amino acids can be made by the body – the other “essential 8” must be consumed
Meat, fish, eggs and milk are important sources of protein

10. What role do vitamins and minerals play in the body?
Vitamins are only needed in small amounts, but help perform chemical reactions
The tools that help put the building blocks together
Two types of vitamins – fat soluble and water soluble
Only fat soluble can be stored in the body
The body also needs a number of minerals in small amounts
Calcium, is needed to produce calcium phosphate that makes up bones and teeth
Iron needed for hemoglobin
Constant supply needed to replace those lost in sweat, urine and digestive waste

11. What should you look out for on a food label?
Fats have more Calories than proteins and carbohydrates due to the extra C-H bonds in carbohydrates or proteins
Remember, percent daily values are based on a 2000 Calorie diet
An active, male teenager will often need about 2800 Calories a day

12. Why does America (and a number of other Western Countries) have a growing obesity problem?
Inactive lifestyles and a high calorie diet
The American Heart Association recommends a diet with a maximum of 30 % of calories from that, of which only 7 % from saturated fats, and 1% from trans fats
Whose job is it to improve the health of a country? Should governments push healthy eating on the population, should insurance companies charge higher premiums to overweight people? Should people be left to eat what they want, as it is their own bodies……. ?

13. Writing assignment
Should schools offer only healthy food choices in the cafeteria and in vending machines? What are other ways that schools and governments can encourage healthy food choices and physical activity

14. Key points What are the two main reasons humans need to eat?
Foods that contain many calories but few raw materials are said to contain empty calories – what do you think the phrase empty calories means?
What six nutrients does the body need?
How are saturated and trans saturated fats similar, how are they different?
What is meant by a balanced diet? How can food labels be use to plan a balanced diet?