whitney & rolfes – understanding nutrition, 12 th edition energy balance and body composition...

Whitney & Rolfes – Understanding Nutrition, 12th Edition

Energy Balance and Energy Balance and Body CompositionBody Composition

Chapter 8


Energy BalanceEnergy Balance

Excess energy is stored as fat Fat is used for energy between meals

Energy balance: energy in = energy out A shift in balance causes weight changes

Not simply fat changes 1 pound of fat = 3500 kcalories


Energy In: Food Energy In: Food CompositionComposition

Direct measure of food’s energy value Bomb calorimeter

Indirect measure of energy released Oxygen consumed

kCalorie calculations



Hunger Physiological response to nerve signals and

chemical messengersHypothalamus

Influences Satiation – stop eating Satiety – not to start eating again



Overriding hunger and satiety Stress eating

External cues Time of day, availability, sight, taste of food

Environmental influences Examples

Disordered eating



Sustaining satiation and satiety Nutrient composition

Protein is most satiatingLow-energy density foods are more satiatingHigh-fiber foods are more satiatingHigh-fat foods – strong satiety signals



The Hypothalamus Control center for eating Integrates messages

Energy intake, expenditure, storage Gastrointestinal hormones


Energy Out Energy Out

Thermogenesis Basal metabolism Physical activity Food consumption Adaptation


Components of Energy Components of Energy Expenditure – Basal Expenditure – Basal

MetabolismMetabolism About two-thirds of energy expended in a

day Metabolic activities

All basic processes of life Basal metabolic rate (BMR)

VariationsWeightLean tissue

Resting metabolic rate (RMR)


Components of Energy Components of Energy Expenditure – Basal Expenditure – Basal

MetabolismMetabolism


Components of Energy Components of Energy Expenditure – Physical Expenditure – Physical

ActivityActivity Voluntary movement of skeletal muscles Most variable component of energy

expenditure Amount of energy needed

Muscle mass Body weight Activity

Frequency, intensity, and duration


Components of Energy Components of Energy Expenditure – Thermic Effect Expenditure – Thermic Effect

of Foodof Food Acceleration of GI tract functioning in

response to food presence Releases heat

Approximately 10 percent of energy intake High-protein foods vs. high-fat foods Meal consumption time frame


Components of Energy Components of Energy Expenditure – Adaptive Expenditure – Adaptive

ThermogenesisThermogenesis Adapt to dramatically changing

circumstances Examples

Extra work done by body Amount expended is extremely variable Not included in energy requirement

calculations


Estimating Energy Estimating Energy RequirementsRequirements

Gender BMR

Growth Groups with

adjusted energy requirements

Age Changes with age

Physical activity Levels of intensity

for each gender Body composition &

body size Height Weight


Defining Healthy Body Defining Healthy Body WeightWeight

Ideal Not appearance based

Perceived body image and actual body sizeDamaging behaviors

Subjective Little in common with health



Body mass index Relative weight for height

BMI = weight (kg)

height (m)2

Health-related classificationsHealthy weight: BMI = 18.5 to 24.9Other classifications

Not a measure of body composition Variations


Body Fat and Its Body Fat and Its DistributionDistribution

Important information for disease risk How much of weight is fat? Where is fat located?

Ideal amount of body fat depends on person General disease risk levels

Young men: 22%; Men over 40: 25% Young women: 32%; Women over 40: 35%



Needing less body fat Some athletes

Needing more body fat Example groups

Fat distribution Visceral fat

Central obesity Subcutaneous fat



Waist circumference Indicator of fat distribution & central obesity

Women: greater than 35 inchesMen: greater than 40 inches

Waist-to-hip ratio Other techniques for body composition

More precise measures


Health Risks Associated Health Risks Associated with Body Weight & Body with Body Weight & Body

FatFat Body weight and fat distribution correlate with disease risk and life expectancy Correlations are not causes

Risks associated with being underweight Fighting against wasting diseases Menstrual irregularities and infertility Osteoporosis and bone fractures



FatFat



FatFat Risks associated with being overweight Obesity is a designated disease

Health risks More likely to be disabled in later years Costs

MoneyLives

Yo-yo dieting



FatFat Cardiovascular disease Elevated blood cholesterol & hypertension Central obesity

Diabetes – type II Central obesity Weight gains and body weight

Cancer Relationship is not fully understood



FatFat Inflammation & metabolic syndrome Change in body’s metabolism

Cluster of symptoms Fat accumulation

Inflammation Elevated blood lipids

Promote inflammation


Highlight 8Highlight 8

Eating Disorders


Eating DisordersEating Disorders

Three disorders Anorexia nervosa Bulimia nervosa Binge eating disorder

Prevalence of various eating disorders Causes

Multiple factors Athletes and eating disorders


Female Athlete TriadFemale Athlete Triad

Disordered eating Unsuitable weight standards

Body composition differences Risk factors for eating disorders in athletes

Amenorrhea Characteristics

Osteoporosis Stress fractures


Female Athlete TriadFemale Athlete Triad


Other Dangerous Other Dangerous Practices of AthletesPractices of Athletes

Muscle dysmorphia Characteristic behaviors Similarities to others with distorted body

images Food deprivation and dehydration practices

Impair physical performanceReduce muscle strengthDecrease anaerobic powerReduce endurance capacity


Anorexia NervosaAnorexia Nervosa

Distorted body image Central to diagnosis

Cannot be self-diagnosed

Malnutrition Impacts brain function and judgment Causes lethargy, confusion, and delirium

Denial Levels are high among anorexics



Need for self-control Protein-energy malnutrition (PEM)

Similar to marasmus Impact on body

Growth ceases and normal development falters

Changes in heart size and strength Other bodily consequences



Treatment Multidisciplinary approach

Food and weight issuesRelationship issues

After recovery Energy intakes and eating behaviors may

not return to normal High mortality rate among psychiatric

disorders


Bulimia NervosaBulimia Nervosa

Distinct and more prevalent than anorexia nervosa True incidence is difficult to establish

Secretive natureNot as physically apparent

Common background characteristics of bulimics



Binge-purge cycle Lack of control Consume food for emotional comfort

Cannot stopDone in secret

PurgeCathartic Emetic Shame and guilt

Negative self-perceptions

Purging Restrictive dieting

Binge eating Stepped Art

Fig. H8-2, p. 266



Physical consequences of binge-purge cycle Subclinical malnutrition

Effects Physical effects

Tooth erosion, red eyes, calloused hands

Clinical depression and substance abuse rates are high



Treatment Discontinuing purging and restrictive diet

habits Learn to eat three meals a day

Plus snacks Treatment team Length of recovery

Overlap between anorexia nervosa and bulimia nervosa


Binge-Eating DisorderBinge-Eating Disorder

Periodic binging Typically no purging

Contrast with bulimia nervosa Compare with bulimia nervosa

Feelings Differences between obese binge eaters

and obese people who do not binge Behavioral disorder responsive to treatment


Eating Disorders in Eating Disorders in SocietySociety

Society plays central role in eating disorders Known only in developed nations More prevalent as wealth increases

Food becomes plentiful

Body dissatisfaction Characteristics of disordered eating

whitney & rolfes – understanding nutrition, 12 th edition energy balance and body composition...

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