1. ENERGY METABOLISM
An overview for 7th and 8th grade students attending a Montessori Farm School
Viola Holmes, MS, RD

2. What is Metabolism?
The chemical changes in living cells by which the body grows, maintains itself, and breaks down tissue

3. 2 Metabolic Processes: Anabolism – the building up of body tissues
Catabolism – the breaking down of body tissues

4. Metabolism of Food Begins with eating (or ingestion)
The food is broken down
The products of digestion + O2 = energy
Getting rid of waste materials

5. The 3 Dietary Sources of Fuel
Cho = 9 calories/gram
Pro = 4 calories/gram
Fat = 4 calories/gram

6. Body fuel sources are: CHO --- Glucose PRO --- Amino Acids
FAT --- Fatty acids
Once digestion is completed we have these three

7. Carbohydrates to Glucose
Provides our fastest and most efficient source of energy
Absorbed from the digestive tract as glucose
Glucose is maintained in the blood at constant levels so that it can be catabolized for energy when needed
Produces CO2 and H2O waste products

8. Glucose Storage Glucose converts to glycogen for storage
Glycogen is stored in the liver and muscles
The body has limited glycogen stores
When glycogen stores are filled excess glucose is converted to fat and deposited in adipocytes

9. Fats to Fatty Acids Fats are converted to fatty acids for fuel
Alternate source of energy if cho stores are depleted
Ketones are the waste product of fats and can be effectively eliminated by the urinary system (as long as they are not over produced)

10. Fat Storage Almost all cells can store fatty acids
The body generates adipocytes for storage
Adipocytes can be created but not destroyed
Once fats are in these tissue, it is very difficult for the body to use them as an energy source

11. Proteins to Amino Acids
Proteins are broken down to amino acids in the intestines and then go to the liver
Broken down into 20 amino acids, which are required for cellular anabolism
May undergo further chemical change to form hormones and digestive enzymes
Alternate source of energy if cho stores are depleted
Produces energy and nitrogen-containing waste product called urea

12. Amino Acid Storage
Throughout the body amino acids are bunched up as proteins or they are freely available
A.A.s have huge uses
If excessive protein is consumed, there will be increased levels of protein in the urine

13. What is our preferred energy source?
CARBOHYDRATES
Breads, cereals, rice, pasta
Fruits and fruit juices
milk

14. The final step of food to fuel
Once converted and stored, “foodstuffs” are available for use
Glucose, fatty acids, and amino acids still need to be converted to ATP before they are used as energy
ATP is the energy
ATP = adenosine triphosphate

15. The Role of Vitamins Vitamins are accessory organic compounds
They are essential to enhancement of the metabolism of cho, pro, and fats

16. An individuals energy needs depends on:
Their basal metabolic rate (BMR)
To maintain body temperature, to pump blood, for brain activity
Their body composition
Lean tissue requires more fuel than fat tissue
Their activity level
changes daily

17. Basal Energy Expenditure (BEE)
Formula for males:
66+(13.7xwt kg)+(5.0xht cm)-(6.8xage)
Formula for females:
655 + (9.6xwt kg)+(1.7xht cm)-(4.7xage)

18. Activity Factors Sedentary Adolescent – 1.3
Moderately Active –
Very Active –
Multiply BEE x Activity Factor = Daily Calorie Needs

19. A Balanced Diet Fuels Fitness
55-60% carbohydrates
15-20% protein
25-30% fat
Fiber is also important