Body Composition Questions and Answers 2023

Body Composition Questions and Answers 2023 Body Composition The relative proportions of fat and lean mass in an individual Importance of BC Assess health risk Assess effectiveness of interventions To set weight classifications for athletes Fat Mass (FM) The absolute amount of body fat Includes all extractable lipids from adipose and other tissue Fat-free Mass (FFM) Lipid-free chemicals and tissues Water, muscle, bone, connective tissue, organs Relative Body Fat Percentage (%BF) FM as a percentage of total body mass (TBM) Muscle vs. Fat Tissue Muscle tissue may comprise up to 50% of TBM, fat tissue can expand to 80% TBM Adipose Tissue Specialized for storage of energy in the form of triglycerides (fat) Fat accounts for 80% of energy stored in the body Adipocytes = fat cells Two Types of Fat Cells White and Brown Adipocytes 30-50 billion fat cells in an adult of normal weight. White Adipose Cells Most fat is stored here in one large fat droplet, nuclei are flat and on the outer rim of cell. Can expand in size until fat is used. Brown Adipose Cells Contain small fat droplets, more vascularized, nuclei are more centrally located, more mitochondria Better for heat generation Plays trivial role in weight maintenance Hypertrophy Increase in cell size Overweight Characteristics Adipocytes reach capacity and new ones form, usually occurs when TBF exceeds 30 kg. Hyperplasia Increase in cell number Obese Person 75-80 billion fat cells Adipocytes Once they are created they cannot be destroyed, the size can only decrease. Cellulite An enlarged fat cell can cause buldging between connective fibers that keeps skin attached to the body, creates a dimply effect Body Fat Regulation Sex hormones, local factors, genetics regulate _______. Fat is continually flowing in and out of cells at all times regardless of nutritional state. Fatty Acids Fat flows in and out of cells in the form of molecules called _______. Triglycerides We store fat in the form of _______. These are too big to pass in and out of cells. Triglyceride Components Glycerol + 3 fatty acids = _______. Two Types of Adipose Tissue Metabolism Lipogenesis and Lipolysis Lipogenesis Deposition of fat. Carbohydrates and protein from food are converted to triglycerides in the liver and stored in Adipose tissue. INSULIN (and glucagon- pancreas). Lipolysis Chemical decomposition and release of fat from adipose tissue. This predominates over Lipogenesis when extra energy is required. Lipoprotein Lipase (LPL) Insulin stimulates _______ which acts to break down triglycerides to free fatty acids so they can enter the adipocyte. Hormone Sensitive Lipase (HSL) Multi-enzyme complex which hydrolyzes the triglyceride into free fatty acids and glycerol. Essential Fat Fat in the heart, lungs, liver, spleen, kidneys, intestines, muscles, CNS, bone marrow. Normal physiologic function requires this. Women need 12%, men need 3% Storage Fat Major fat depot consisting of fat accumulation in adipose tissues. Has Visceral and Subcutaneous fat. Men and women have similar amounts, 12%:15% Total Fat Essential Fat + Storage Fat Two Locations of Adipocytes Subcutaneous and Visceral Subcutaneous Adipose tissue beneath the skin Visceral Adipose tissue within and surrounding organs. Direct Assessment of BC Chemical analysis of the body; human cadaver. Indirect Assessment of BC Estimation of body composition by hydrostatic weighing, simple anthropometric measurements or other procedures. Body Mass Index (BMI) Equation Body Mass/height squared (kg/m2) Anthropometry Standardized techniques to quantify or predict body size, weight, proportion, and shape. Body Density Body mass per unit of body volume Densitometry Archimedes' principle of water displacement to estimate body density. Hydrostatic weighing, underwater weighing. GOLDEN STANDARD. Height and Weight Tables Designed to assess overweightness based on sex and bone frame size. Many problems. Problems with Height and Weight Tables Invalidated estimates of frame sizes Data from white populations Mortality data not related to obesity No assessment of BC Body Mass Index (BMI) Higher association with body fat and disease risk than height-weight tables. Still does not account for % body fat. (Mislabeled fit person as overweight) Everyone can calculate. BMI Classifications Underweight < or = 18.5 Normal Weight = 18.5-24.9 Overweight = 25-29.9 Obesity > or = 30 Class I 30-34.9 Class II 35-39.9 Class III 40 Waist Circumfrence Can be used to determine health risk because abdominal obesity (visceral fat) increases health risk. Waist-to-hip Ratio (WHR) Can be used as a simple method for determining body fat distribution Fat Patterning Android Gynoid Android Upper body (abdomen), visceral, hard fat, males Gynoid Lower body (thighs, buttocks), subcutaneous, soft fat, females Common Methods of Body Fat % Measurement Underwater weighing, Dual Energy X-ray Absorptiometry (DEXA), BodPod, Skinfold Thickness, Bioelectrical Impedance Analysis