What is metabolism?Total amount of energy required for each of our physiological actions.
Difference between RMR and BMR?BMR requires extreme fasting conditions, extended periods of rest, tight environmental control.70% of energy we expend each day goes toward non movement related physiological activity.
Thermic effect of foodTEF is used for digestion, absorption and assimilation of ingested food/nutrients.Act of eating increases metabolism BUT IT DEPENDS ON WHICH MACRONUTRIENTS we ingest.Protein has highest TEF ,Fat has lowest.
PHYSICAL ACTIVITYHigh variablesedentary - 10 to 15%Highly active - 30 %
ESTIMATION OF ENERGY NEEDSMeasuring oxygen consumption can help measure energy costDirect mathematical relationship between amount of oxygen we breathe in and amount of energy required by the bodyBurning of fuel mixture (CHO + Fat) provides 4.82 calories per litre of Oxygen.
Putting it into perspective.... At rest, we burn 3.5 ml of oxygen / kg body weight / minute Person = 70 kg Oxygen consumption per hour --- 3.5 x 70 x 60 = 14.7 Oxygen consumption per hour --- 14.7 x 24 = 352 Therefore, Calories burnt = 3.52 x 4.82 = 1700 kcal
When exercise is added : breathing harder and faster ---- more oxygen --- therefore more calories burnt.Oxygen consumption and energy expenditure are closely related!
Indirect calorimetryEstimation of EE via measurement of oxygen consumption and carbon dioxide production.
Direct calorimetryDirect mesurement of heat output by the body, used as index of energy expenditure.
Double labeled waterThe Doubly Labelled Water (DLW) method uses the natural occurring stable isotopes of water (D2O and H218O) to assess energy expenditureThe DLW method is entirely safe and non-restrictive, requires only periodic sampling of body fluids and is well suited for measurement of energy expenditure in free-living or hospitalized patients.The basis of the DLW method is to follow the decline in enrichment of the stable isotopes of oxygen (oxygen-18, 18O) and hydrogen (deuterium, 2H) in body water after initial labeling of the body water pool.
As oxygen-18 is lost from the body in the form of water and carbon dioxide (CO2), whereas deuterium is lost only as water, the difference in loss from the body reflects the CO2 production during the period. Because CO2 production is the result of fat, carbohydrate and protein oxidation, it is an index of energy expenditure.
Bioelectrical impedance analysis• This procedure involves sending a very small current through the body—800 mA at 50 kHz, which is unable to be felt—and measuring its resistance.• The underlying theory to this procedure is : Lean tissue offers less resistance to a current as it contains more water and electrolytes than adipose tissue• This is an affordable and non-invasive method. Another advantage of this procedure is that no special training or skill is required
Several factors may influence its results such asIt quickly estimates the REE based on its estimation hydration state of the subject, prandial/fasting state, exercises, diuretics use, menstrual period,
PREDICTIVE EQUATIONSMifflin-St Jeor (1990) in kcal/dayMale: (10 x W) + (6,25 x H) – (5 x A) + 5Female: (10 x W) + (6,25 x H) – (5 x A) – 161W = Weight in KgH = Height in cmA = Age in years
Owen EquationMenRMR (kcal/day) = 879 +10.2 (weight in kg)Women:RMR (kcal/day) = 795 + 7.2 (weight in kg)Harris and Benedict (1919) in kcal/dayMale 66.4730 + 13.7516(W) + 5.0033(H) – 6.7550(A)Female 655.0955 + 9.5634(W) + 1.8496(H) – 4.6756(A)
Physical activities records:Low cost method that estimates EE from anextremely detailed registry off all physicalactivity studies is limited due to various existingcodesperform dailyDietary questionnaires
ENERGY AVAILABILTYA new concept that is being promoted is that ofenergy availability—that is, the energy that is left for body functions once the energy cost of training istaken into accountThere is evidence that the body can tolerate a certain levelof reduction in energy intake, but energy availabilitylower than 30 kcal (126 kJ) per of lean body mass isassociated with impairments of metabolic, hormonal,and reproductive function.
Deﬁnition of energy availability Total energy intake—energy cost of trainingExample of low energy availability Calculations: Body fat = 10% or 5 kgAthlete = 50 kg, distance runner, Lean body mass (LBM) = 45 kg10% body fat Energy availability = 2250 -1000 = 1250 kcalTraining programme = 1000 = 1250/45 kgkcal/dayEnergy intake = 2250 kcal = 28 kcal/kg LBMExample of adequate energy Calculations: Body fat = 10% or 6 kgavailability Lean body mass (LBM) = 54 kgAthlete = 60 kg distance runner, Energy availability = 3250 -1000 = 2250 kcal10% = 2250/54 kgbody fatTraining program = 1000 kcal/day = 42 kcal/kg LBMEnergy intake = 3250 kcal
• POWER EVENTS OF HIGHER WEIGHT CATEGORY (80 KG AND ABOVE)• ENDURANCE EVENTS• TEAM EVENTS, ATHLETICS AND POWER EVENTS OF MIDDLE WEIGHT CATEGORY (65KG)• EVENTS OF LIGHT WEIGHT CATEGORY• SKILL GAMES
MICRONUTRIENTS• Micronutrients include vitamins and minerals.• They do not provide energy.• They are needed in small quantities.• Deficiencies and excesses of the micronutrients can affect health
Functions of micronutrients- (brief)VITAMIN METABOLIC ROLEA Antioxidant functionThiamin Carbohydrate metabolismRiboflavin Mitochondrial electron transportNiacin Multiple metabolic pathwaysPyridoxine Amino Acid synthesisFolate Red blood cell synthesisCyanocobalamin Red blood cell synthesisAscorbic Acid Antioxidant, Tissue repairD Calcium homeostasis, Immunity
MINERALS PROPOSED BENEFIT SUMMARY OF RESEARCH FINDINGSCalcium Important for forming bone and teeth, clotting blood, and transmitting nerve impulses.Zinc Associated with immunitySelenium Antioxidant.Iron Helps to transport oxygen around the body