Chapters 28 body composition Chapter 30 exercise and weight control PET3380 Exam 4 Study Guide 1 Know and understand the principle of Archimedes and how it applies to the procedure of human body volume measurements Archimedes developed a fundamental principle to evaluate human body composition measuring volume of irregularly shaped object requires submersion in water and collection of the overflow an object submerged or floating in water becomes buoyed up by counterforce that equals weight of the volume of water it displaces so essentially an object loses weight in water object s loss of weight in water equals weight of volume of water it displaces so its specific gravity refers to the mass of an object in air divided by its loss of weight in water o specific gravity weight in air loss of weight in water o or also weight in air weight in air weight in water this water submersion allows us to determine body volume density body mass volume and from this we can estimate body fat 2 Understand the differences and usefulness of different body composition and anthropometric assessment procedures discussed in the text and class What are the general assumptions used by indirect measures direct measurements chemical analysis of animal carcass or human cadaver o high accuracy the body tissues composition indirect measurements hydrostatic weighing simple anthropometric measurements and other clinical and lab procedures o mathematical equations to indirectly predict body s fat based on assumed constancy of o anthropometric using height weight circumferences and skinfolds to estimate body BMI body mass height underweight for female 18 5 kg m2 normal 18 5 24 9 overweight 25 29 9 obese class I 30 34 9 obese class II 35 39 9 class III 40 kg m2 fails to distinguish between fat muscle mass and bone density does not correlate well to estimating body fat 5 error in reading circumferences used to assess patterns of body fat distribution measurement sites abdomen arm butt hips calf forearm hips thigh mid thigh waist android body type apple shaped fat deposition in the abdomen more health concerning more likely to cause heart disease gynoid body type pear shaped fat deposits in gluteal and femoral regions skin fat folds the amount of subcutaneous fat is proportional to total body fat the more dense someone is the leaner they are calipers used to measure fat thickness in designated areas 7 site method or 3 site sex specific method o bioelectrical impedance impedance to electrical current flow related to quantity of total body water current flows better through hydrated fat free mass compared to fat o bod pod determines volume by measuring initial volume of empty chamber and then volume of chamber with person inside o DEXA dual energy x ray absorpiometry originally used for bone scans often used to assess BMD of people for determining osteoporosis o hydrostatic weighing considered gold standard for measurements based on Archimedes principle and specific volume measure whole body density using ratio of body mass to body volume 3 What are the body composition differences between males and females males body fat average 15 range from 10 22 o overfatness above 20 females body fat average 26 range from 20 32 o overfatness above 30 4 Understand the difference between essential and storage fat and the difference between FFM and LBM essential fat biologically necessary for normal functioning o fat in lungs heart liver spleen kidneys intestines muscles and lipid rich tissues of nervous system and bone marrow o sex specific fat 3 5 in male and 12 15 in female storage fat fat deposited in adipose tissue o includes visceral fatty tissues that protect organs within thoracic and abdominal cavities from trauma and larger adipose tissue volume deposited beneath skin s surface fat free body mass FFM body mass devoid of all extractable fat body mass minus fat mass lean body mass LBM contains small percentage of non specific essential fat equivalent to approximately 3 body fat in normal adults healthy and hydrated the only difference between FFM and LBM is the essential fat component present in LBM 5 How does energy balance and weight loss affect body composition if energy is balanced energy output energy input body comp will stay relatively the same if it is not kept balanced body composition will differ o decrease if weight is lost input output increase if weight is gained input output 6 Understand the potential impact of diet and exercise on obesity e g what are the differences of dieting alone as compared to dieting and exercise combined diet exercise will yield more weight loss than either alone o diet exercise as well as the exercise only groups lost more fat pounds than the diet only group which lost both muscle and fat o diet exercise group gained one pound of lean tissue o exercise only group gained 3 pounds of lean tissue diet exercise is most healthy and beneficial form of losing weight 7 Understand the concept of the energy balance equations energy input energy output helps to maintain weight energy input energy output gains weight energy input energy output loses weight energy output o basal metabolic rate accounts for 80 95 of total daily energy expenditure and is a major contributor to maintenance of body weight slows with age o thermic effect of food energy it takes body to digest food 10 energy day o physical activity both daily functional and exercise activity maybe 5 3500 calories equals 1 lb of fat 8 Know the changes that occur in fat cells during weight gain and weight loss adipose tissue mass increases in two ways o hypertrophy cells increase in size have better chance of beating obesity o hyperplasia cells increase in number problematic these people are predisposed to obesity can t reduce number of fat cells so once you have them you re stuck with them o to some extent fat comes from parents o proliferate during different developmental times of a person s life greatest times of proliferation are during first 1 5 years of life and during pre pubescent stage o overeating overfeeding by parent at young age baby and toddler ages creates more fat cells in body after weight reduction the size of fat cells decreased by number doesn t substantially change so it s suggested that hypertrophic individuals have better chance of beating obesity 9 What is BMI BMI ratio of body mass to height o body mass height o underweight for female 18 5 kg m2 o normal 18 5 24 9 o overweight 25 29 9 o obese class I 30 34 9 o
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