energy metabolism
DESCRIPTION
ENERGY METABOLISM. ENERGY METABOLISM. The study of how the body uses, stores and burns energy. Carbohydrates Fats Proteins. ENERGY BALANCE. ENERGY INPUT = ENERGY OUTPUT. Calories from food intake. = Digestion, metabolism, transport of nutrients, physical activity. - PowerPoint PPT PresentationTRANSCRIPT
ENERGY METABOLISM
ENERGY METABOLISM
The study of how the body uses, stores and burns energy
CarbohydratesFats Proteins
ENERGY BALANCE
ENERGY INPUT = ENERGY OUTPUTCalories 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
• Equilibrium input = output, no weight change
• Positive energy balanceinput > output, increase in weight(necessary during pregnancy, for infants and children)
• Negative energy balanceinput < output, decrease in weight
ENERGY BALANCE
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???
CALORIMETRY
production
Good agreement between direct and indirect calorimetry
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 = 4.184 kilojoules
BOMB CALORIMETRY
DIRECT CALORIMETRY
ENERGY VALUES OF FOODSCALORIMETERkcal/g
BODY kcal/gMETABOLIZABLE ENERGY
Atwater Factors
Carbohydrate 4.1 4Fats 9.4 9Proteins * 5.6 4*Alcohol 7.0 7Fiber No calories -* The difference is due to energy content of urea, which cannot be further metabolized in the body
QuestionMr. I.L. Nihari consumes 585 g carbohydrates, 150 g protein110 g fatHow many calories a day is he consuming?
585 x 4 = 2,340 kcal150 x 4 = 600 kcal110 x 9 = 990 kcalTOTAL = 3930 kcal/day
CO2 O2
INDIRECT CALORIMETRY
INDIRECT CALORIMETRY
Vol of CO2 produced
Vol of O2 consumed
C6H12O6 + 6O2 6CO2 +6H2O + Heat 664 Kcal
Therefore R.Q. for glucose oxidation = 6/6 = 1
C15H31COOH + 23O2 16CO2 + 16H2O + 2313Kcal
Therefore R.Q. for Palmitic acid oxidation = 16/23 = 0.7
Respiratory Quotient =
RESPIRATORY QUOTIENT
CARBOHYDRATE = 1.0FATS = 0.7Proteins = 0.8Mixed diet = 0.85
R.Q. > 1.0 Carbohydrates Fats
R. Q. = 0.7 Starvation, Diabetes
DAILY ENERGY EXPENDITURE
DEE = Basal metabolic rate + physical activity + Thermic effect of food + Thermogenesis
BASAL METABOLIC RATE (BMR)/ RESTING METABOLIC RATE (RMR)
• BMR: The energy expenditure of a person mentally and bodily at rest in a thermoneutral environment 12-18 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
• BMR is calculated by measuring O2 consumption for 6 min and using the following factor
one liter of O2 consumed = 4.825 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 1600 -1800 kcal/dayFemales 1200 – 1450 kcal/day
BASAL METABOLIC RATE (BMR)/ RESTING METABOLIC RATE (RMR)
FACTORS AFFECTING BMRIncrease• 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 lactationDecrease• Low calories intake• Aging
DAILY ENERGY EXPENDITURE
DEE = Basal metabolic rate + physical activity + Thermic effect of food + Thermogenesis
PHYSICAL ACTIVITY
• Most important factor in determining the DEE of an individual
Modest = 0.3 x BMRModerate = 0.4 x BMRHeavy = 0.5 x BMR
DAILY ENERGY EXPENDITURE
DEE = Basal metabolic rate + physical activity + Thermic effect of food + Thermogenesis
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 150-300 kcal
DAILY ENERGY EXPENDITURE
DEE = Basal metabolic rate + physical activity + Thermic effect of food + Thermogenesis
FACTORS AFFECTING ENERGY FACTORS AFFECTING ENERGY REQUIREMENTS REQUIREMENTS
1. BODY SIZE: with an in muscle mass
2. AGE :
22 – 50 yrs supposing at 2000 Kcal
51- 75 yrs 90% of age 22-50 yrs – 1800 Kcal
>75 yrs 75-80% of age 22-50 yrs – 1500/1600
Kcal
FACTORS AFFECTING ENERGY FACTORS AFFECTING ENERGY REQUIREMENTS REQUIREMENTS
PHYSICAL ACTIVITY:The most important factorFor person with very heavy physical activity add
600-900 Kcal
PREGNANCY AND LACTATION:
Pregnancy (2nd and 3rd Trimester) +300 KcalLactation + 500
Kcal
ENERGY REQUIREMENTS
* MOST COMMONLY USED METHOD (TEF is ignored)
Energy REQ = BMR + Physical Activity
1. BMR = wt (kg) x 25 Kcal2. Physical Activity:
Modest = 0.3 x BMRModerate = 0.4 x BMRHeavy = 0.5 x BMR
ENERGY REQUIREMENTS
Example: 70 Kg Man, Moderately Active
BMR = 70 x 25 = 1750 Kcal
Physical activity = 0.4 x 1750 = 700 Kcal
Total = 2450 Kcal/day
How to lose excess body wt?
Mr I. L. NihariHe 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?
CASE
Diagnosis of Overweight and Obesity
– Height-weight tables – Light, medium & heavy frame– Skin-fold thickness (specific areas)
Triceps– Body Mass Index
Body Mass Index (BMI)Most commonly used to assess obesity-
BMI = Wt (Kg)/Ht (m2)
Underweight < 20.0Normal (healthy) 20.0 – 24.9Overweight 25.0 -29.9Obese ≥ 30Morbidly Obese > 45.1
STEP 1
Calculate his BMI:
BMI = Body wt. in KgHeight in m2
= 120/(1.734)2 = 40.0
STEP 2
Calculate his caloric requirement on the basis of current body weightCaloric requirement = BMR + Physical activity (modest)
(BMR x 0.3) 120 x 25 = 1875 + 900 = 3,900 kcal
STEP 3
Calculate his ideal body weight
Ideal body weight = 100 + (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)
STEP 4Calculate his adjusted body weight
adjusted body weight = Ideal body weight + 25% of (current body weight - ideal body weight)
73 + 11.8 = 84.8 kg
Calculate his caloric requirement on the basis of adjusted body weightCaloric requirement = BMR + Physical activity (modest)
(BMR x 0.3)
84.8 x 25 = 2120 + 636 = 2756 kcal/day
STEP 5
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
STEP 6
Caloric Intake needed/day = 2756 – 513 = 2243 ≈2250 Kcal/day
(2756 = Adjusted body wt. basis)
STEP 7
Comparison of energy requirements at various body weights
• Current body weight = 3900 - 513 = 3387 Kcal
• Ideal Body weight = 2372 - 513 = 1859 Kcal
• Adjusted body weight = 2756 – 513 = 2250 Kcal
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
• EXERCISE : Exercise (walk 1-2 miles/day or other physical activities)
• BEHAVIOUR MODIFICATION
ADVICE FOR CHANGE IN LIFE STYLE
THE ENDTHE END