1. ENERGY METABOLISM

2. The study of how the body uses, stores and burns energy
ENERGY METABOLISM
The study of how the body uses, stores and burns energy
Carbohydrates
Fats
Proteins

3. ENERGY INPUT = ENERGY OUTPUT
ENERGY BALANCE
ENERGY INPUT = ENERGY OUTPUT
Calories from food intake
= Digestion,
metabolism, transport of nutrients, physical activity
Maintenance of energy balance
- contributes to health and well being
- prevents the risk of developing many common health problems

4. ENERGY BALANCE Equilibrium input = output, no weight change
Positive energy balance
input > output, increase in weight
(necessary during pregnancy, for infants and children)
Negative energy balance
input < output, decrease in weight

5. Energy balance – Some questions??
How much energy is contained a particular meal? Different foods?
How can the energy in foods be measured?
How can energy expended by an individual be measured?
i.e., how would you measure energy input and out put???

6. CALORIMETRY Good agreement between direct and indirect calorimetry
production
Good agreement between direct and indirect calorimetry

7. ENERGY VALUES OF FOODS
1 Kilocalorie = amount of heat required to raise the temperature of 1 kg of water through 1˚C (15˚ to 16˚C).
1 kcal = 1 Calorie (capital C) in nutrition
1 kcal = kilojoules

8. BOMB CALORIMETRY

9. DIRECT CALORIMETRY

10. ENERGY VALUES OF FOODS Carbohydrate 4.1 4 Fats 9.4 9 Proteins * 5.6 4*
CALORIMETER
kcal/g
BODY kcal/g
METABOLIZABLE ENERGY
Atwater Factors
Carbohydrate
4.1 4
Fats
9.4 9
Proteins *
5.6 4*
Alcohol
7.0 7
Fiber
No calories -
* The difference is due to energy content of urea, which cannot be further metabolized in the body

11. Question Mr. I.L. Nihari consumes 585 g carbohydrates, 150 g protein
110 g fat
How many calories a day is he consuming?
585 x 4 = 2,340 kcal
150 x 4 = 600 kcal
110 x 9 = 990 kcal
TOTAL = 3930 kcal/day

12. CO2 O2

13. INDIRECT CALORIMETRY

14. INDIRECT CALORIMETRY Respiratory Quotient = Vol of CO2 produced
Vol of O2 consumed
C6H12O6 + 6O CO2 +6H2O + Heat 664 Kcal
Therefore R.Q. for glucose oxidation = 6/6 = 1
C15H31COOH + 23O CO2 + 16H2O Kcal
Therefore R.Q. for Palmitic acid oxidation = 16/23 = 0.7
Respiratory Quotient =

15. RESPIRATORY QUOTIENT CARBOHYDRATE = 1.0 FATS = 0.7 Proteins = 0.8
Mixed diet = 0.85
R.Q. > 1.0 Carbohydrates  Fats
R. Q. = 0.7 Starvation, Diabetes

16. DAILY ENERGY EXPENDITURE
DEE = Basal metabolic rate + physical activity + Thermic effect of food + Thermogenesis

17. BASAL METABOLIC RATE (BMR)/ RESTING METABOLIC RATE (RMR)
BMR: The energy expenditure of a person mentally and bodily at rest in a thermoneutral environment hours after a meal
For a sedentary person BMR accounts for 60% to 70% of the total body energy expenditure
Functioning of lungs, heart, kidneys, brain; maintenance of ionic gradients; reactions of metabolic reactions…..
RMR: If a person is not fasting or completely rested
Typically 6% higher than the BMR

18. BASAL METABOLIC RATE (BMR)/ RESTING METABOLIC RATE (RMR)
BMR is calculated by measuring O2 consumption for 6 min and using the following factor
one liter of O2 consumed = kcal
Q: If 1.5 liters of O2 are consumed in 6 minutes calculate the BMR of a patient .
Approx equal to 25 kcal/kg/day
Males kcal/day
Females 1200 – 1450 kcal/day

19. FACTORS AFFECTING BMR Increase Lean body mass Larger surface area
Sex (M > F)
Body temperature: in fever 30-35%  at 40˚C (104oF)
Nervous sytem activity (release of norepinephrine)
Hormones, esp. Thyroid hormone
pregnancy and lactation
Decrease
Low calories intake
Aging

20. DAILY ENERGY EXPENDITURE
DEE = Basal metabolic rate + physical activity + Thermic effect of food + Thermogenesis

21. PHYSICAL ACTIVITY
Most important factor in determining the DEE of an individual
Modest = 0.3 x BMR
Moderate = 0.4 x BMR
Heavy = 0.5 x BMR

22. DAILY ENERGY EXPENDITURE
DEE = Basal metabolic rate + physical activity + Thermic effect of food + Thermogenesis

23. Thermic effect of food
Energy required to digest, process and absorb food
Also known as Specific Dynamic Action
 O2 consumption associated with digestion and absorption of foods
Protein 12% of total energy expenditure
Carbohydrates 6% of total energy expenditure
Fats 2% of total energy expenditure
Mixed diets 5-10% of total energy expenditure
3000 Kcal diet, TEF kcal

24. DAILY ENERGY EXPENDITURE
DEE = Basal metabolic rate + physical activity + Thermic effect of food + Thermogenesis

25. FACTORS AFFECTING ENERGY REQUIREMENTS
1. BODY SIZE:  with an  in muscle mass
2. AGE :
22 – 50 yrs supposing at 2000 Kcal
yrs 90% of age yrs – 1800 Kcal
>75 yrs % of age yrs – 1500/ Kcal

26. FACTORS AFFECTING ENERGY REQUIREMENTS
PHYSICAL ACTIVITY:
The most important factor
For person with very heavy physical activity add Kcal
PREGNANCY AND LACTATION:
Pregnancy (2nd and 3rd Trimester) Kcal
Lactation Kcal

27. ENERGY REQUIREMENTS
* MOST COMMONLY USED METHOD (TEF is ignored) Energy REQ = BMR + Physical Activity 1. BMR = wt (kg) x 25 Kcal 2. Physical Activity: Modest = 0.3 x BMR Moderate = 0.4 x BMR Heavy = 0.5 x BMR

28. ENERGY REQUIREMENTS Total = 2450 Kcal/day
Example: 70 Kg Man, Moderately Active
BMR = 70 x 25 = Kcal
Physical
activity = 0.4 x = 700 Kcal
Total = 2450 Kcal/day

29. How to lose excess body wt?

30. CASE Mr I. L. Nihari He is 5’9’’ tall & weighs 264 lbs (120 kg).
The doctor has advised him to lose 10 kg over a period of 5 months.
Q. what should be his caloric intake to reduce the weight?
Q. How many calories would he need to decrease per day to achieve the desired target?
Q. What weight reduction plan would you advise this patient?

31. Diagnosis of Overweight and Obesity
Height-weight tables
Light, medium & heavy frame
Skin-fold thickness (specific areas) Triceps
Body Mass Index

32. Most commonly used to assess obesity-
Body Mass Index (BMI)
Most commonly used to assess obesity-
BMI = Wt (Kg)/Ht (m2)
Underweight < 20.0
Normal (healthy) – 24.9
Overweight
Obese ≥ 30
Morbidly Obese > 45.1

33. = 120/(1.734)2 = 40.0 STEP 1 Calculate his BMI: BMI = Body wt. in Kg
Height in m2
= 120/(1.734)2 = 40.0

34. STEP 2
Calculate his caloric requirement on the basis of current body weight
Caloric requirement =
BMR + Physical activity (modest)
(BMR x 0.3)
120 x 25 = = 3,900 kcal

35. STEP 3 = 160 lbs (~73 kg) Calculate his ideal body weight
Ideal body weight = (5 x 3)
(100 lbs for 5 ft; 5 lbs for every inch above 5 ft for women
106 lbs for 5 ft; 6 lbs for every inch above 5 ft for men)
= 160 lbs (~73 kg)

36. STEP 4 Calculate his adjusted body weight adjusted body weight =
Ideal body weight + 25% of (current body weight - ideal body weight)
= 84.8 kg

37. STEP 5
Calculate his caloric requirement on the basis of adjusted body weight
Caloric requirement =
BMR + Physical activity (modest)
(BMR x 0.3)
84.8 x 25 = = 2756 kcal/day

38. STEP 6
How many grams of body weight does he need to reduce per day? (10 kg in 5 months)
10 kg in 5 months =
2 Kg / month = 2000/30 = 67g/day
Caloric value of 67g adipose tissue
(85% fat, 15% water) = ?
67 x 9 x 0.85 = 513 Kcal

39. STEP 7
Caloric Intake needed/day =
2756 – 513 = 2243
≈2250 Kcal/day
(2756 = Adjusted body wt. basis)

40. Comparison of energy requirements at various body weights
Current body weight = = Kcal
Ideal Body weight = = Kcal
Adjusted body weight = 2756 – 513 = Kcal

41. ADVICE FOR CHANGE IN LIFE STYLE
DIET: Eat a balanced diet, low in Calories
FAD DIETS DON’T WORK
↓ intake of high caloric density foods
Fried foods, sweets etc.
Substitute low fat milk for whole milk
Low fat yogurt for full fat yogurt
 the intake of vegetables & fruits (Foods with high fiber content, Rich in vitamins & minerals

42. ADVICE FOR CHANGE IN LIFE STYLE
EXERCISE :  Exercise (walk 1-2 miles/day or other physical activities)
BEHAVIOUR MODIFICATION

43. THE END