NUTR SCI 132 Lecture 17 Outline of Last Lecture I. Blood Lipids and RiskII. Diet and Blood LipidsOutline of Current Lecture I. Energy Balance, Body Composition and Obesitya. Total Energy ExpenditureII. Factors that shape Obesity Riska. Thrifty Metabolismb. Set Point Theoryc. Fat DistributionCurrent LectureI. Energy Balance, Body Composition and Obesitya. Julie Pattersonb. Energy Balancei. Proportion Distortionii. Thermodynamic Law1. Energy cannot be created or destroyed, only transferrediii. 1 kcal = 1 caloriec. Weight Regulationi. Weight reflects the amount of energy in the body1. Balance = weight is stablea. Energy Intake = Energy Expenditured. Total Energy expenditurei. Basal Metabolic Rate (60-75%) - BMR1. Energy expended through involuntary activity onlya. Heartbeat, breathing, chemical reactions, no muscular activity (voluntary)2. Factors that affect BMRa. Increase MBRi. Increased lean body massii. Regular or frequent mealsiii. Exposure to cold temperaturesiv. FeverThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.v. Caffeinevi. Stressvii. Pregnancy and breastfeedingb. Factors that decrease BMRi. Loss of lean body massii. Meal skipping, dieting or food restrictioniii. Starvation or fastingiv. Exposure to warm temperaturesv. Aging vi. Female gendervii. Sleepii. Thermic Effect of Food (5-10%)1. Energy cost of eating2. Includes digesting, transporting, storing or metabolizing foodiii. Physical Activity (25-35%) – Most Variable1. Voluntary muscular effort2. Sedentarya. +20-40%3. Light Activitya. 55-65% BMRb. Walking, Bicycling4. Heavya. 80-100% BMRb. Elite athletes in endurance sportII. Factors that shape Obesity Riska. Ecological Perspectivei. Thrifty Metabolism1. Genetically Determined, energy efficient metabolism2. Promotes the storage of fat3. Advantageous during periods of food shortages4. May contribute to obesity epidemic in modern societya. Pima Indiansi. Group in Mexico vs. Arizonab. “Genes load the gun, and the environment pulls the trigger”ii. Set Point Theory1. Concept that the body has a “set point” weighta. Body resist changes in weightiii. Anthropometric Assessment1. Frame sizea. Wrist measurement2. Ideal Body Weight3. Body Compositiona. Total body mass = Sum of lean mass + fat massb. Methods for determining body fati. Underwater weighing = gold standard1. Fat floats, muscle sinks2. Need to expel all air or results will be skewedii. Bioelectrical Impedance1. Hydration skews resultsiii. Skin Fold Calipersiv. Fat Distribution1. Subcutaneousa. Fat under the skinb. Calipers measure this2. Viscerala. Abdominal fatb. ‘Toxic’3. Intramusculara. Fat within the muscle itselfv. Body Mass Index1. Measurement of your weight relative to your height2. Pro-Easy to obtain3. Cons-Does not distinguish fat tissue from lean muscle
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