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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 CompositionEnergy In: Food Composition
• Direct measure of food’s energy value• Bomb calorimeter
• Indirect measure of energy released• Oxygen consumed
• kCalorie calculations
Energy In: Food IntakeEnergy In: Food Intake
• Hunger• Physiological response to nerve signals and
chemical messengers• Hypothalamus
• Influences
• Satiation – stop eating• Satiety – not to start eating again
Energy In: Food IntakeEnergy In: Food Intake
• Overriding hunger and satiety• Stress eating
• External cues• Time of day, availability, sight, taste of food
• Environmental influences• Examples
• Cognitive influences• Disordered eating
Energy In: Food IntakeEnergy In: Food Intake
• Sustaining satiation and satiety• Nutrient composition
• Protein is most satiating
• Low-energy density
• High-fiber foods
• High-fat foods – strong satiety signals
Energy In: Food IntakeEnergy In: Food Intake
• 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
Energy Out: Basal MetabolismEnergy Out: Basal Metabolism
• About two-thirds of energy expended in a day
• Metabolic activities• All basic processes of life• Basal metabolic rate (BMR)
• Variations
• Weight
• Lean tissue
• Resting metabolic rate (RMR)
Energy Out: Physical ActivityEnergy Out: Physical Activity
• Voluntary movement of skeletal muscles• Most variable component of energy
expenditure• Amount of energy needed
• Muscle mass• Body weight• Activity
• Frequency, intensity, and duration
Energy Out: Thermic Effect of Energy Out: Thermic Effect of FoodFood
• 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
Energy Out: Adaptive Energy Out: 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 WeightDefining Healthy Body Weight
• Ideal• Not appearance based
• Perceived body image and actual body size
• Damaging behaviors
• Subjective• Little in common with health
Defining Healthy Body WeightDefining Healthy Body Weight
• Body mass index• Relative weight for height
• BMI = weight (kg)
height (m)2
• Health-related classifications• Healthy weight: BMI = 18.5 to 24.9
• Other classifications
• Not a measure of body composition • Variations
Body Fat and Its DistributionBody Fat and Its Distribution
• Important information for disease risk• How much of weight is fat?• Where is fat located?
• Ideal amount of body fat depends on person
Body Fat and Its DistributionBody Fat and Its Distribution
• Needing less body fat• Some athletes
• Needing more body fat• Example groups
• Fat distribution• Visceral fat
• Central obesity
• Subcutaneous fat
Body Fat and Its DistributionBody Fat and Its Distribution
• Waist circumference • Indicator of fat distribution & central obesity
• Women: greater than 35 inches
• Men: greater than 40 inches
• Waist-to-hip ratio
• Other techniques for body composition• More precise measures
Health Risks Associated with Health Risks Associated with Body Weight & Body FatBody Weight & Body Fat
• 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
Health Risks Associated with Health Risks Associated with Body Weight & Body FatBody Weight & Body Fat
• Risks associated with being overweight• Obesity is a designated disease
• Health risks
• More likely to be disabled in later years• Costs
• Money
• Lives
• Yo-yo dieting
Health Risks Associated with Health Risks Associated with Body Weight & Body FatBody Weight & Body Fat
• Cardiovascular disease• Elevated blood cholesterol & hypertension• Central obesity
• Diabetes – type II• Central obesity• Weight gains and body weight
• Cancer• Relationship is not fully understood
Health Risks Associated with Health Risks Associated with Body Weight & Body FatBody Weight & Body Fat
• Inflammation & metabolic syndrome• Change in body’s metabolism
• Cluster of symptoms
• Fat accumulation• Inflammation
• Elevated blood lipids• Promote inflammation
• Fit and fat versus sedentary and slim
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
Other Dangerous Practices of Other Dangerous Practices of AthletesAthletes
• Muscle dysmorphia• Characteristic behaviors• Similarities to others with distorted body
images
• Food deprivation and dehydration practices• Impair physical performance
• Reduce muscle strength
• Decrease anaerobic power
• Reduce 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
Anorexia NervosaAnorexia Nervosa
• 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
Anorexia NervosaAnorexia Nervosa
• Treatment• Multidisciplinary approach
• Food and weight issues
• Relationship 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 nature
• Not as physically apparent
• Common background characteristics of bulimics
Bulimia NervosaBulimia Nervosa
• Binge-purge cycle• Lack of control• Consume food for emotional comfort
• Cannot stop
• Done in secret
• Purge• Cathartic
• Emetic
• Shame and guilt
The Vicious Cycle of Restrictive The Vicious Cycle of Restrictive Dieting & Binge EatingDieting & Binge Eating
Bulimia NervosaBulimia Nervosa
• 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
Bulimia NervosaBulimia Nervosa
• 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