A. Humannutrition andhealthA2: Energy in human diets
Energy in diets Cell respiration involves the release of  energy from foods such as  fat, carbohydrate or protein. Foods...
What is food energy and how is itmeasured? Humans are autotrophs and get energy from organic molecules from other organism...
Compare the energy contentper100 g of carbohydrate, fatand protein Energy   in 100 g Fats        Carbohydrates   Proteins...
How is food energy metabolized?
Why are fats so energy rich?  Energy in 100 g Fats              Carbohydrates   Proteins4 000 kJ            1 760 kJ     ...
Let’s check the   food label again! What percentage calories from fat are in this burger? (295/563)   x 100 = 52.4% Wha...
How much energy do weneed? Energy    needs vary according to    size, age, gender and level of activity, but    you can c...
Staple diets vary by geographicalregion and culture   Availability and    sustainability of    land are major    factors ...
Carbohydrate-rich diets   Two types:   Large amounts of sugar: increase the risk of    developing type II diabetes and t...
Fat-rich diets They   can cause obesity Other consequences depend on the type  of fatty acids contained in the fats. Fat...
Protein-rich diets Protein   is only used as an energy source if  it is present in the diet in excess or if  amounts of c...
Eating and apetite   Appetite is controlled in the hypothalamus of    the brain. Control is both nervous and    hormonal:...
Nervous-hormonal pathway
Calculating Body Mass Index      (BMI)       BMI=    body mass (kg)             Calculate     your BMI                 h...
Obesity   A BMI of 30.0 or above is catalogued as obesity.   In some countries rates of clinical obesity are    increasi...
Anorexia nervosa - causes   Anorexia nervosa is an eating disorder in    which the patient severely limits food intake   ...
Anorexia nervosa -consequences Since   the amount of carbohydrates and  fats consumed are too small, the body  starts bre...
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A2 Energy In Human Diets

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A2 Energy In Human Diets

  1. 1. A. Humannutrition andhealthA2: Energy in human diets
  2. 2. Energy in diets Cell respiration involves the release of energy from foods such as fat, carbohydrate or protein. Foods eaten in bulk to supply energy are called staple foods. Human societies are very diverse in their choice of staple energy sources.
  3. 3. What is food energy and how is itmeasured? Humans are autotrophs and get energy from organic molecules from other organisms. Typically these are fats, lipids and carbohydrates.One food Calorie = 1kcal or 1000 calOne calorie is the energy needed to raise 1gof water by 1°COne food Calorie = 4.18kJ (kilo joules) SIunit
  4. 4. Compare the energy contentper100 g of carbohydrate, fatand protein Energy in 100 g Fats Carbohydrates Proteins4 000 kJ 1 760 kJ 1 720 kJ956kcal 421kcal 411kcal
  5. 5. How is food energy metabolized?
  6. 6. Why are fats so energy rich? Energy in 100 g Fats Carbohydrates Proteins4 000 kJ 1 760 kJ 1 720 kJ956kcal 421kcal 411kcal
  7. 7. Let’s check the food label again! What percentage calories from fat are in this burger? (295/563) x 100 = 52.4% Whatpercentage of fat by weight is in this burger? (33/219) x 100 = 15.1%
  8. 8. How much energy do weneed? Energy needs vary according to size, age, gender and level of activity, but you can calculate the amount you take in and the amount you need. Amount taken in – amount used = amount stored
  9. 9. Staple diets vary by geographicalregion and culture Availability and sustainability of land are major factors in the food energy source of a population Initiatives like «Golden Rice» can use genetic engineering to supplement staple foods to reduce malnutrition
  10. 10. Carbohydrate-rich diets Two types: Large amounts of sugar: increase the risk of developing type II diabetes and tooth decay. Large amounts of starch: usually from cereals or root crops (tubers). If digested slowly, it can be a healthy diet. If digested quickly, promtes the development of type II diabetes. All diets with excessive amounts of carbohydrates can cause obesity
  11. 11. Fat-rich diets They can cause obesity Other consequences depend on the type of fatty acids contained in the fats. Fats, unlike carbohydrates, cannot be used for anaerobic respiration, so they are unsuitable for athletes in strength events, like running and weight lifting.
  12. 12. Protein-rich diets Protein is only used as an energy source if it is present in the diet in excess or if amounts of carbohydrates and fat are very small. Weight lifters and body builders sometimes have a high-protein diets and they are sometimes used as a method for slimming.
  13. 13. Eating and apetite Appetite is controlled in the hypothalamus of the brain. Control is both nervous and hormonal: some hormones trigger appetite- stimulating neurons, others trigger appetite- inhibiting neurons. An empty stomach releases the hormone gherin, which triggers appetite-stimulating hormones, leading to hunger. When food enters the stomach, gherin production is stopped, reducing hunger.
  14. 14. Nervous-hormonal pathway
  15. 15. Calculating Body Mass Index (BMI)  BMI= body mass (kg)  Calculate your BMI height (m)BMI Below 18.5 18.5 – 24.9 25.0 – 29.9 30.0 and aboveCategory Underweight Normal Overweight Obese  Limitations of the BMI using this table:  Race, gender and age are not considered  No distinction is made on body fat/water/muscle composition
  16. 16. Obesity A BMI of 30.0 or above is catalogued as obesity. In some countries rates of clinical obesity are increasing for many reasons:  Availability of cheap, high-energy food (junk food)  Large portion sizes served in restaurants (super size)  Increase use of vehicles for transport instead of walking  Increase in office-based jobs replacing jobs involving physical activity  Sedentary recreation (videogames) replacing active recreation (sports)
  17. 17. Anorexia nervosa - causes Anorexia nervosa is an eating disorder in which the patient severely limits food intake (voluntary starvation). It is a medical condition with complex mental and physiological causes. It is closely associated with body image and meeting aesthetic standards imposed by culture. It is most common in females, but does occur in males.
  18. 18. Anorexia nervosa -consequences Since the amount of carbohydrates and fats consumed are too small, the body starts breaking down its own proteins. Hair becomes thinner and can drop out. Skin becomes dry and bruises easily Blood pressure is reduced, slow heart rate and poor circulation No ovulation or menstrual cycles and infertility.

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