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Energy Balance and Body Composition - Edl

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Energy Balance and Body Composition
Chapter 8
Energy Balance
Excess energy stored as fatFat used for energy between mealsEnergy balance: energy in = energy outImbalance causes weight changesNot simply fat changesClassic rule1 pound of fat = 3500 kcaloriesNot exactly correctDiffers with gender and weight
Measuring Food Energy
Direct measure of food’s energy valueBomb calorimeterIndirect measure of energy releasedOxygen consumedkCalorie calculations
Food Intake
HungerPhysiological response to nerve signals and chemical messengersHypothalamusInfluencesSatiation – signal to stop eatingSatiety – signal to not to start eating again
Hunger, Satiation, and Satiety
Factors That Influence Eating
Overriding hunger and satietyStress eatingExternal cuesTime of day, availability, sight, taste of foodEnvironmental influencesExamplesCognitive influencesDisordered eating
Nutrient Composition for Sustained Satiation and Satiety
Protein is most satiatingLow-energy densityHigh-fiber foodsHigh-fat foods – strong satiety signals
The Hypothalamus
Control center for eatingIntegrates messagesEnergy intake, expenditure, and storageGastrointestinal hormonesInfluence appetite control and energy balance
Energy Out
ThermogenesisHeat generationMeasure of energy expendedTotal energy componentsBasal metabolismPhysical activityFood consumptionAdaptation
Basal Metabolism
Represents about two-thirds of daily energyMetabolic activitiesAll basic processes of lifeBasal metabolic rate (BMR)VariationsWeightLean tissueResting metabolic rate (RMR)
Factors that Affect the BMR
aThe BMR begins to decrease in early adulthood (after growth and development cease) at a rate of about 2 percent/decade.A reduction in voluntary activity as well brings the total decline in energy expenditure to about 5 percent/decade.bIf two people weigh the same, the taller, thinner person will have the faster metabolic rate, reflecting the greater skinsurface, through which heat is lost by radiation, in proportion to the body's volume (see Figure 8-5, p. 239).cFever raises the BMR by 7 percent for each degree Fahrenheit.dProlonged starvation reduces the total amount of metabolically active lean tissue in the body, although the decline occurs sooner and to a greater extent than body losses alone can explain. More likely, the neural and hormonal changes that accompany fasting are responsible for changes in the BMR.eThe thyroid gland releases hormones that travel to the cells and influence cellular metabolism. Thyroid hormone activity can speed up or slow down the rate of metabolism by as much as 50 percent.
Physical Activity
Voluntary movement of skeletal musclesMost variable component of energy expenditureAmount of energy neededMuscle massBody weightActivityFrequency, intensity, and duration
Thermic Effect of Food
Acceleration of GI tract functioning in response to food presenceReleases heatApproximately 10 percent of energy intakeHigh-protein foods versus high-fat foodsMeal consumption time frame
Adaptive Thermogenesis
Adapt to dramatically changing circumstancesExamplesExtra work done by bodyAmount expended is extremely variableNot included in energy requirement calculations
Components of Energy Expenditure
Estimating Energy Requirements
GenderBMRGrowthGroups with adjusted energy requirementsAgeChanges with age
Physical activityLevels of intensity for each genderBody composition and body sizeHeightWeight
Ideal Body Weight: Criteria
The criterion of fashionPerceived body image and actual body sizeDamaging behaviorsSocial standards for “ideal”SubjectiveLittle in common with healthThe criterion of healthEnough fat to meet basic needsNot so much to incur health risks
Tips for Accepting a Healthy Body Weight
• Valueyourself and others for human attributes other than body weight. Realize that prejudging people by weight is as harmful as prejudging them by race, religion, or gender.• Use positive, nonjudgmental descriptions of your body.• Accept positive comments from others.• Focus on your whole self including your intelligence, social grace, and professional and scholastic achievements.• Accept that no magic diet exists.• Stop dieting to lose weight. Adopt a lifestyle of healthy eating and physical activity permanently.• Follow the USDA Food Patterns. Never restrict food intake below the minimum levels that meet nutrient needs.• Become physically active, not because it will help you get thin but because it will make you feel good and improve your health.• Seek support from loved ones. Tell them of your plan for a healthy life in the body you have been given.• Seek professional counseling,notfroma weight-loss counselor, but from someone who can help you make gains in self-esteem without weight as the primary focus.• Appreciate body weight for its influence on health, not appearance
Body Mass Index (BMI)
BMI Table
BMI and Body Shapes
Distribution of Body Weights in US Adults
Body Fat and Its Distribution
Important information for disease riskHow much of weight is fat?Where is fat located?Ideal amount of body fat depends on person
SOURCE: L. G.Borrudand coauthors. Body composition data for individuals 8 years of age and older: US population, 1999-2004,Vital and Health Statistics 11 (2010): 1-87; ACSM's Health-Related Physical Fitness Assessment Manual, 2nd ed.(Baltimore, M.D.: Lippincott Williams & Wilkins, 2008), p. 59.
Central Obesity
Needing less body fatSome athletesNeeding more body fatExample groupsFat distributionVisceral fatCentral obesitySubcutaneous fat
“Apple”and“Pear”Body Shapes Compared
Waist Circumference
Indicator of fat distribution and central obesityWomen: greater than 35 inchesMen: greater than 40 inchesWaist-to-hip ratioOther body composition measurement techniquesMore precise measures
Common Methods Used to Assess Body Fat
Health Risks Associated with Body Weight and Body Fat
Body weight and fat distribution correlate with disease risk and life expectancyCorrelations are not causesRisks associated with being underweightFighting against wasting diseasesMenstrual irregularities and infertilityOsteoporosis and bone fractures
BMI and Mortality
Risks Associated With Being Overweight
Obesity is a designated diseaseHealth risksMore likely to be disabled in later yearsCostsMedical costsLost productivityLives
Specific Disease Risks
Cardiovascular diseaseElevated blood cholesterol and hypertensionCentral obesityDiabetes – type IICentral obesityWeight gains and body weightCancerRisk of some cancers increases with body weightRelationships not fully understood
Inflammation and the Metabolic Syndrome
Change in body’s metabolismCluster of symptomsFat accumulationInflammationElevated blood lipidsPromote inflammationFit and fat versus sedentary and slimFitness offers many health benefits
Eating Disorders
Highlight 8
Eating Disorders, continued
Three disordersAnorexia nervosaBulimia nervosaBinge eating disorderPrevalence of various eating disordersCausesMultiple factorsAthletes and eating disorders
Female Athlete Triad
Disordered eatingUnsuitable weight standardsBody composition differencesRisk factors for eating disorders in athletesAmenorrheaCharacteristicsOsteoporosisStress fractures
The Female Athlete Triad Illustrated
Other Dangerous Practices of Athletes
Muscle dysmorphiaCharacteristic behaviorsSimilarities to others with distorted body imagesFood deprivation and dehydration practicesImpair physical performanceReduce muscle strengthDecrease anaerobic powerReduce endurance capacity
Tips for Combating Eating Disorders
General Guidelines• Never restrict food amounts to below those suggested for ade­quacy by the USDA Food Patterns (see Table 2-2 on p. 44).• Eat frequently. Include healthy snacks between meals. The person who eats frequently never gets so hungry as to allow hunger to dictate food choices.• If not at a healthy weight, establish a reasonable weight goal based on a healthy body composition.• Allow a reasonable time to achieve the goal. A reasonable loss of excess fat can be achieved at the rate of about 10 percent of body weight in 6 months.• Establish a weight-maintenance support group with people who share interests.Specific Guidelines for Athletes and Dancers• Replace weight-based goals with performance-based goals.• Restrict weight-loss activities to the off-season.• Remember that eating disorders impair physical performance. Seek professional help in obtaining treatment if needed.• Focus on proper nutrition as an important facet of your training, as important as proper technique.
Anorexia Nervosa
Distorted body imageCentral to diagnosisCannot be self-diagnosedMalnutritionImpacts brain function and judgmentCauses lethargy, confusion, and deliriumDenialLevels are high among anorexics
Characteristics of Anorexia Nervosa
Need for self-controlImpact on bodyGrowth ceases and normal development faltersChanges in heart size and strengthMineral imbalanceDeath can occur from multiple organ system failure
Treatment of Anorexia Nervosa
Multidisciplinary approachFood and weight issuesRelationship issuesTreatment involves family membersDifferent approaches for low, medium, and high risk patientsHigh mortality rate among psychiatric disorders
Bulimia Nervosa
Distinct and more prevalent than anorexia nervosaTrue incidence difficult to establishSecretive natureNot as physically apparentCommon background characteristics of bulimics
Characteristics of Bulimia Nervosa
Binge-purge cycleLack of controlConsume food for emotional comfortCannot stopDone in secretPurgeCatharticEmeticShame and guilt
The Vicious Cycle of Restrictive Dieting and Binge Eating
SteppedArt
Negativeself-perceptions
Purging
Restrictive dieting
Binge eating
Effects of Bulimia Nervosa
Physical consequences of binge-purge cycleSubclinical malnutritionEffectsPhysical effectsTooth erosion, red eyes, and calloused handsHigh rates of clinical depression and substance abuse
Treatment of Bulimia Nervosa
Discontinuing purging and restrictive diet habitsLearn to eat three meals a dayPlus snacksTreatment teamLength of recoveryOverlap between anorexia nervosa and bulimia nervosa
Diet Strategies for Combating Bulimia Nervosa
Planning Principles• Plan meals and snacks; record plans in a food diary prior to eating.• Plan meals and snacks that require eating at the table and using utensils.• Refrain from finger foods.• Refrain from "dieting" or skipping meals.Nutrition Principles• Eat a well-balanced diet and regularly timed meals consisting of a variety of foods.• Include raw vegetables, salad, or raw fruit at meals to prolong eating times.• Choose whole-grain, high-fiber breads, pasta, rice, and cereals to increase bulk.• Consume adequate fluid, particularly water.Other Tips• Choose foods that provide protein and fat for satiety and bulky, fiber-rich carbohydrates for immediate feelings of fullness.• Try including soups and other water-rich foods for satiety.• Choose portions that meet the definition of "a serving" according to the USDA Food Patterns (pp. 42-43).• For convenience (and to reduce temptation) select foods that naturally divide into portions. Select one potato, rather than rice or pasta that can be overloaded onto the plate; purchase yogurt and cottage cheese in individual containers; look for small packages of precut steak or chicken; choose frozen dinners with measured portions.• Include 30 minutes of physical activity every day—exercise may be an important tool in defeating bulimia.
Binge-Eating Disorder
Periodic bingingTypically no purgingContrast with bulimia nervosaSimilarities to bulimia nervosaFeelingsDifferences between obese binge eaters and obese people who do not bingeBehavioral disorder responsive to treatment
Eating Disorders in Society
Society plays central role in eating disordersKnown only in developed nationsMore prevalent as wealth increasesFood becomes plentifulBody dissatisfactionIncidence in young peopleIncreased steadily since the 1950s

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Energy Balance and Body Composition - Edl