Lecture 4 Energy Potential of Food

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Lecture 4 Energy Potential of Food
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ENERGY

• Nutrients ? Fuel ?? Energy
• ? ?
• Food Work

Human Nutrition
Lecture 4 Energy Potential of Food
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ENERGY ? WORK

• Kilojoules (kJ) ? metric
• Kilocalories (kcal) ? imperial
• 1 kilojoule is the amount of energy required to
  heat 1kg water by 1oC
• 1 kilocalorie 4.16 (4.2) kilojoules

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Lecture 4 Energy Potential of Food
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ENERGY ? WORK

• Bomb Calorimeter

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Lecture 4 Energy Potential of Food
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Bomb Calorimeter

• a sample of food is burned
• with oxygen (mimics oxidation in the body)
• amount of heat released temp. rise
• represents amount of energy in that food sample

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ENERGY IN FOOD(Availability)

• Protein 23 kJ/g 92 available
• CHO 16 kJ/g 99 available
• Fat 39 kJ/g 95 available
• Alcohol 29 kJ/g 100 available

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Lecture 4 Energy Potential of Food
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ENERGY IN FOOD (Atwater Factors)

• Protein 1gram 17 kJ ? 4 kcal
• CHO 1gram 16 kJ ? 4 kcal
• Fat 1gram 37 kJ ? 9 kcal
• Alcohol 1gram 29 kJ ? 7 kcal

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Lecture 4 Energy Potential of Food
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Calculation of energy distribution

• Suppose daily consumption is..
• 90g Protein
• 350g CHO
• 120g Fat
• 40g Alcohol

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Lecture 4 Energy Potential of Food
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What is the Energy distribution?

• 90g Protein 1g17 kJ, 90 x 171530 kJ
• 350g CHO 1g16 kJ, 350 x 165600 kJ
• 120g Fat 1g37 kJ, 120 x 374440 kJ
• 40g Alcohol 1g29 kJ, 40 x 29 1160 kJ
• Total 12730 kJ

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Lecture 4 Energy Potential of Food
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Calculate Energy distribution

• Protein 1530/12730 12 of Etotal
• CHO 5600/12730 44 of Etotal
• Fat 4440/12730 35 of Etotal
• Alcohol 1160/12370 9 of Etotal

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Lecture 4 Energy Potential of Food
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What are the recommendations?

• PROTEIN
• non-athletes 10-15 of Etotal
• athletes 12-17 of Etotal
• CARBOHYDRATE
• non-athletes 50-55 of Etotal
• athletes 55-70 of Etotal

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Lecture 4 Energy Potential of Food
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What are the recommendations?

• FAT
• non-athletes lt35 of Etotal
• athletes lt30 of Etotal
• ALCOHOL
• females 20g/day (2 std drinks)
• males 40g/day (4 std drinks)

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Lecture 4 Energy Potential of Food
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How does our intake compare with recommendations?

• PROTEIN
• intake 12 of Etotal
• recommended 10-15 (non-athletes)
• 12-17 (athletes)
• CARBOHYDRATE
• intake 44 of Etotal
• recommended 50-55 (non-athletes)
• 55-70 (athletes)

Human Nutrition
Lecture 4 Energy Potential of Food
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How does our intake compare with recommendations?

• FAT
• intake 35 of Etotal
• recommended lt35 (non-athletes)
• lt30 (athletes)
• ALCOHOL
• intake 40g (9 of Etotal)
• recommended 20g/day (female)
• 40g/day (male)

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Lecture 4 Energy Potential of Food
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ENERGY FOR HUMANS

• FOOD ? digested ? primary nutrients
• 
  ?
• 
  FUEL
• fuel stored and retrieved on demand

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Lecture 4 Energy Potential of Food
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How is fuel stored?

• FAT as Triglyceride in adipose tissues
• CARBOHYDRATE as Glycogen in skeletal muscle and
  liver
• PROTEIN is NOT stored
• ALCOHOL is NOT stored

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Lecture 4 Energy Potential of Food
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Non energy yielding nutrients

• water
• dietary fibre
• vitamins
• minerals

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Lecture 4 Energy Potential of Food
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Recommended Reading

• Wahlqvist ML
• Food and Nutrition (2nd Edition)
• Chapter 11 Food energy and energy
  expenditure
• pp. 171-175 ONLY
• Library
• High demand 4-hour collection
• Call NumberCE0426

Human Nutrition
Lecture 4 Energy Potential of Food