Post on 28-Dec-2015
MicronutrientsMicronutrients
NutrientsNutrients
– are need to effectively extract energy from theare need to effectively extract energy from the
macronutrients via catabolismmacronutrients via catabolism
MacronutrientsMacronutrients– Protein, Carbohydrate and LipidsProtein, Carbohydrate and Lipids
–Contain stored energyContain stored energy
Vitamins and Minerals Vitamins and Minerals
Energy ContentEnergy Content
Carbohydrate contain 16 kj/gramCarbohydrate contain 16 kj/gram
ProteinProtein contain 17 kj/gramcontain 17 kj/gram
Fat contains 37 kj/gramFat contains 37 kj/gram
Alcohol contains 29 kj/gramAlcohol contains 29 kj/gram
How is energy content of How is energy content of food measured?food measured?
– BombBomb calorimetercalorimeter Measures the energy released when theMeasures the energy released when the
food is burntfood is burnt.
This includes energy from indigestible foods as This includes energy from indigestible foods as
well as digestible food .well as digestible food . The energy content of this "fibre" must be The energy content of this "fibre" must be
subtracted from the bomb calorimeter subtracted from the bomb calorimeter
measurement.measurement.
Bomb CalorimeterBomb Calorimeter
Food Sample
Thermometer
Water
Ignition fuse
Bomb
Water Tank
Stirrer
The extraction of energy The extraction of energy from foodfrom food
Repackaging energy inRepackaging energy in ATPATP packetspackets
– Glucose = approx 100 ATPGlucose = approx 100 ATP
– But catabolism maximum yield is 38 But catabolism maximum yield is 38 ATP / glucoseATP / glucose
– as little as 0 ATP as inas little as 0 ATP as in Brown Adipose TissueBrown Adipose Tissue
The rest is lost as The rest is lost as heatheat
CatabolismCatabolism
Energy Needs of the Body
Total Kilojoule Requirements
• The average day can be dived into three stagesThe average day can be dived into three stages:
Rest,Rest, • Energy need for each stage Energy need for each stage are about:are about:
Rest, 2000kjRest, 2000kj
Work 3-4000kjWork 3-4000kj
Play 3-4000kjPlay 3-4000kj
• Over all per day = from 6000kj for total bed restOver all per day = from 6000kj for total bed rest
to 14,000 for a very active individualto 14,000 for a very active individual
• The need depend on body mass and sexThe need depend on body mass and sex
WorkWork and and PlayPlay
Basal Metabolism
– The energy needs of the body at The energy needs of the body at complete rest complete rest
• Is not really “Is not really “basalbasal” as it can ” as it can change due to: change due to: temperaturetemperature
and diet.and diet.
Used for all Internal energy needsUsed for all Internal energy needsRecycle tissueRecycle tissueImmunityImmunity
Body warmthBody warmthReduced by Tissue decreaseReduced by Tissue decrease
Measure of energy needs of the body
Indirect CalorimetryIndirect Calorimetrymeasuring the amount of measuring the amount of COCO22 breathed out breathed out .
People can have a respirometer People can have a respirometer attached while movingattached while moving
Whole body:Whole body:
people can be housed in a room people can be housed in a room
connected to connected to COCO22 monitors for air In and out monitors for air In and out
Which nutrients are used first for energy? Actually all macronutrients are
used for energy all the time.
Different material in different Different material in different tissues eg.:tissues eg.:
The brain needs glucoseThe brain needs glucose
Aerobic Muscles use fatAerobic Muscles use fat
The liver uses mainly excess proteinThe liver uses mainly excess protein.
Calculate Body Mass Index (BMI)
From % Body fat– Measured with
Skinfold thickness buoyancy Electrical conduction
Desire % Body FatDesire % Body Fat
Body Condition Female Male Unhealthy <15% <10% Lean 17-22% 10-15 Normal 22-25% 15-18% Above Average 25-29% 18-20% Over weight 29-35% 20-25% Obese 35+% 25+%
Dangers of Under and Over weight
Framington study– indicated obesity increased
chance of early death cardiovascular disease diabetes
Underweight
Framington study indicated underweight increased – chance of early death
– infectious disease
– cancer
Anorexia nervosa and bulimia nervosa
Effect of fat Effect of fat distribution typedistribution type
Andomorphs– More likely to suffer
cardiovascular disease Gynomorphs
– Less likely to suffer cardiovascular disease
Benefits of Obesity
Obese people do not get Obese people do not get osteoporosisosteoporosis.
This may be due to their higher insulin secretion reducing This may be due to their higher insulin secretion reducing
calcium lost in the urine. calcium lost in the urine.
Nurture Theories
• Eating to satisfy : Eating to satisfy :
• Boredom Boredom • Parents Parents
• Stress Stress
• CultureCulture
• Effect of ageEffect of age
• Ego Ego
Most obese adults were slim when youngMost obese adults were slim when young
Obesity may be caused by phycologyObesity may be caused by phycology
Nature Theories
Obesity caused by physiology Dieting does not help
Ageing
Muscle tone Muscle tone
Diet induced ThermogenesisDiet induced Thermogenesis
Glycogen storage Glycogen storage variationsvariations
Need large food intake to maintain Nitrogen BalanceNeed large food intake to maintain Nitrogen Balance
Benefits of Obesity
Obese people do not get Obese people do not get osteoporosisosteoporosis.
This may be due to their higher insulin secretion reducing This may be due to their higher insulin secretion reducing
calcium lost in the urine. calcium lost in the urine.
Why Dieting Doesn't WorkWhy Dieting Doesn't Work Reduced energy intake causes the Reduced energy intake causes the
body to adapt:body to adapt: lowers “basal metabolismlowers “basal metabolism””
burns up fatburns up fat
reduces energy using tissuereduces energy using tissue
– lean body mass lean body mass
When you go off the dietWhen you go off the diet
use less energyuse less energy
get fatter than beforeget fatter than before