12 Energy Balance

Energy BalanceBody Composition & Weight

Management

Energy Balance

The relationship between energy intake (consumption of food) & energy output.

Energy intake is the amount of calories contained in the diet.

Energy output is the amount of fuel used mainly for basic body function, physical activity & the processing of food

(+) energy balance – weight gain. (-) energy balance – weight loss

ENERGY OUT: FUEL FOR WORK

Energy represents the capacity to do work. 6 forms of energy: chemical, mechanical,

heat, electrical,light and nuclear Our cell get their energy from ‘chemical

energy’ held in the molecular bonds of carbs, fats, protein as well as alcohol

Our body, possess stores of chemical energy that can be used to produce electrical energy for creation of nerve impulses, to produce heat or cold and mechanical work

Measuring of Energy Expenditure

Direct Calorimetry› Measurement of body heat production› Advantage: Provide an accurate measure

of total body energy expenditure› Disadvantage: cannot follow rapid changes

in energy release (high intensity exercise).

Calorimetric Chamber

Direct Calorimetry

CO2 + H2O +

GlucoseLipids + O2Proteins

Heat (kcal)

Lipids: 9.4 kcal/gGlucose: 4.2 kcal/gProteins: 4.3 kcal/

Measuring of Energy Expenditure

Indirect Calorimetry› Measurement of respiratory gases (O2

consumption & CO2 release)› Glucose & fat metabolism depend on O2

availability to produce CO2 & H2O. The amount of O2 and CO2 exchanged in the lungs normally equals that used and released by body tissues

› E.g. Metabolic Chart, Douglas bag

Indirect Calorimetry

The Respiratory Exchange Ratio (RER)

To estimate the amount of energy used by the body, we need to know the type of food (carbs, fats or protein) being oxidized.

Indirect calorimetry measures the amount of CO2 released (VCO2) and oxygen consumption (VO2)

The ratio between these two values is termed RER

RER = VCO2

VO2

The Respiratory Exchange Ratio (RER)

Caloric Equivalence of the Respiratory Exchange Ratio and % kcal From CHO & Fats

Component Of Energy Expenditure

Basal Metabolic Rate (BMR)

Represent the energy requirements of the many different cellular & tissue activities that are necessary to continuing in physiological activities in resting, post absorptive state throughout most of the day.

Measurement of basal metabolism during a specific period (1hour or 1 day)

Basal energy expenditure (BEE) represents the BMR extrapolated over a 24 hour period.

Training method of estimating BMR

All formula here use metabolic rate in kcal per day, body weight (kg) and height (cm)

Method 1 – simple application of body mass

BMR = BW X 24hr

› Method 2 – Harris & Benedict equation of BMR

MEN: BMR = 66 + (13.7 X BW) + (5 X ht) – (6.8 x age)

WOMEN: BMR = 65 + (9.6 X BW) + (1.7 X ht) – (4.7 X age)

Training method of estimating BMR

Calculated estimates of BMR for a 35year old man who is 180 Ib (82kg) & 5’ 11” (180 cm) using the three different equations:

› 1. 1968 kcal› 2. 1853 kcal

BMR

These calculation is not very sensitive to body composition and tend to over estimate BMR in heavier individuals with a higher %FM & to under estimate BMR in athlete with a higher %FFM

BMR for males tend to be a little higher than for females since men tend to have a greater skeletal muscle to adipose tissue ratio

BMR /kg of BW is highest during infancy and decline with age, because infant tends to have a higher % of FFM than adults and are also engage in very rapid tissue growth

Factors That Affect BMR

Factor Effect on BMR

Age Lean body mass diminisheswith age, slowing BMR

Height In tall, thin people, BMR ishigher (greater skin surface)

Growth In children & pregnantwomen, BMR higher

Body Composition More lean tissue, BMRhigher (e.g., male)



Fever Fever raises BMR

Stresses Stress raise BMR

Environmental temperature

Both heat & cold raise BMR

Fasting/starving Both lowers BMR



Malnutrition Lowers the BMR

Hormones Premenstrual hormonesslightly raise BMR

Smoking Nicotine increase energyexpenditure

Caffeine Caffeine increase energyexpenditure

Sleep BMR is lowest when sleeping

Resting Metabolic Rate (RER)

Represent BMR plus small amount of additional energy expenditure associated with eating and previous muscular activity.

Resting energy expenditure (RER) represents the RER extrapolated over a 24 hour period.

BMR is often used interchangeably with RER

RER tends to be 10% greater than BMR

Thermal Effect of Activity (TEA)

For inactive people, BMR is the greatest contributor to total energy expenditure

However, for athletes & active people, TEA can be the greatest contributor.

Exercise training increases TEA throughout a day & can increase BMR as well because of repair & recovery.

To estimate TEA – keep activity log over a 24 hour period & then apply energy equivalent coefficients.

Thermal Effect of Food (TEF)

Process of food digestion & absorption requires energy & produce heat

TEF is proportional to the energy taken in & is usually estimated at 10% of energy intake

E.g., A person who ingests 2000kcal expends about 200kcal on TEF.

TEF is greater for :› high protein food than high fat foods› A meal eaten all at once rather than spread out

over a couple of hours TEF is reduced in obese people (may

contribute to their efficient storage of fat)

Adaptive Thermogenesis (AT)

Adjustments in energy expenditure related to changes in environment (e.g., extreme cold), and to physiological events (e.g., overfeeding, trauma, and changes in hormone status)

How to Estimate EnergyRequirements

Date required – age (years), weight (kg), height (m), physical activity table.

› For men 19 years & older EER = 662 – 9.53 x age + PA x [(15.91 x wt) + (539.6

x ht)]

› For women 19 years & older EER = 354 – 6.91 x age + PA x [(9.36 x wt) + (726 x

ht)]

Physical Activity (PA) Factor forEER Equations

M W PA

Sedentary

1.0 1.0 Only those physical activitiesrequired for normalindependent living

Low active

1.11 1.12 1.5 to 3.0 miles/day

Active 1.25 1.27 3 to 10 miles/day

Very active

1.48 1.45 > 10 miles/day

How to Estimate EnergyRequirements

Example: an active 30 year old male who is 1.8m tall & weighs 80.9kg.

EER = 662 – 9.53 x 30 + 1.25 x [(15.91 x 80.9) + (539.6 x 1.8)]

= 3199 kcal/day

Assessing Body Composition

Densitometry› hydrostatic weighing

Anthropometric› Skinfold measurement, Body Mass Index

(BMI), Waist to Hip Ratio (WHR) Others

› Bioelectrical Impedance Analysis (BIA), Dual Energy X-Ray Absorptiometry (DEXA), CT scan

Hydrostatic weighing

Bioelectrical ImpedanceAnalysis (BIA)

Dual Energy X-RayAbsorptiometry Scan (DEXA)

Skinfold Measurement

When Energy Balance Goes Awry

Overweight› BMI greater than 25 but less than 30.› Bodyweight 10 - 20%

above desirable weight.

Obese› BMI greater or equal to 30.› Bodyweight 20% or more above desirable weight.

Underweight› BMI under 19.› 15 – 20% or more below desirable weight for height.

Health Risk of BeingOverweight & Obesity

Hypertension› More likely to have high blood pressure (a major

risk factor for heart disease and stroke) Heart disease (HD) & stroke

› Hypertension and a very high cholesterol level can lead to HD. Being OW also contribute to angina and sudden death from HD or stroke.

Diabetes› OW people are twice likely to develop type 2

diabetes (major cause of early death, HD, kidney disease, stroke & blindness)


Cancer› OW men – risk of colon, rectum, prostate cancer

Sleep apnea› Sleep apnea cause a person to stop breathing for

short periods during sleep (may cause daytime sleepiness and even heart failure)

Osteoarthritis› Extra weight appears to increase the risk of

osteoarthritis by placing extra pressure on weight bearing joint and wearing away the cartilage.


Gout› Gout – caused by high level of uric acid in

the blood that deposited in the joint, often seen in OW population.

Gallbladder disease› Also known as gallstones are more

common in OW population. It is still not clear how being OW may cause gallbladder disease.

Underweight

Causes› Altered response to hunger, appetite, satiety› Eating disorder – distorted body image, compulsive dieting and over exercising› Metabolic and heredity factor› Prolonged stress› Addiction to alcohol and drugs› Inadequate diet

Underweight

Weight gain strategies:› Have small frequent meals with nutrient dense and

energy dense food and beverage› Drink fluids at the end or between meal› Use high calorie weight gain beverages and foods› Use timer or other cues to prompt eating› Use a balance vitamin/mineral supplement to

ensure deficiency does not contribute to poor appetite

› Perform regular resistance training program› Limit aerobic training› Prescribe drugs – appetite stimulant

12 Energy Balance

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