Kinesiology 1020

• Body Composition and Obesity

  
• BMI (body mass Index)


  Weight(g)/height Cml

  
• BMI


  The most common measure for obesity

  
• Lambert Adolphe Jacques Quetelet developed the formula for Body mass Index For Adult's

  
• BMI Classifications


  • Under 18.5 = UNDERWEIGHT, Increase HEALTH Risk
  • 18.5-25 = HEALTHY, Least HEALTH Risk
  • 25-30 = OVERWEIGHT, Increase HEALTH RISK
  • 30 and up = OBESE, 30.0-34.9 = HIGH HEALTH RISK
  • 35.0-39.9 = VERY HIGH HEALTH RISK
  • 40.01 and up = EXTREMELY HIGH RISK

  
• Limitations of BMI


  • Cannot distinguish between different body compositions
  • BMI can classify Obesity but has limitations to people with high body mass

  
• Athletes who have HIGH Muscle mass

  • HIGH BMI but low body fat and low disease risk
• Assessment of Body Composition


  • Body fat is related to diseases
  • Body weight is related to tissue's related to bones, organs tissue's

  
• 2 Compartment Model


  • Less precise
  • Fat-free mass - everything that is not fat (bone, organs, muscle's, connective tissues)

  
• Multi-Compartment (3) Model's


  3C = Fat mass, Bone mass, Lean mass (fat and Jone)
• Cadaveric Analysis


  • ONLY TRUE way of measuring body fat and body Soft tissue Composition Minerals
  • Takes DIRECT measure of body tissue's
  • Impractical
  • most accurate
  • used to Validate the accuracy of other devices

  
• Densitometry


  • Based on Archimede's principle
  • Density is proportional to FFM
  • Density used to calculate % BF
• FAT Techniques of Assessing Body Fat

  • Air displacement plethysmography (Bodpod)
  • Hydrodensitometry (under water weighing)

  
• Bioelectrical Impedance Analysis (BIA)


  • Sends week electrical current over the body
  • 2 compartment model-fat and lean tissue
  • Fat = insulator (Water free; hold's on to heat)
  • Lean = Conductor (HAS WATER, Can Conduct electrical Currents)
  • The slower the electrical current the more fat
• Features of BIA


  • Affected by hydration Status (How much water one has drank)
  • Provide regional body
• Things to note about BIA
• Skinfold measure's


  • Requires Caliper's only
  • Take mm measure's of skin and fat thickness at various body sites
  • Subcutaneous-only measure's fat under the skin
  • Sites : Bis, trices, Subscapular, Supra-iliac , thigh, Calf abdomen

  
• Body fat prediction using Skinfold Equations

  
• Computed Tomography (CT)


  • Can identify disease or injury within various regions of the body
  • Can be used for body composition but IT IS NOT because of high radiation exposure
  • 4 model (can look at every single tissue)
  • High density tissue Show up Whiter (bone)
  • Lower density (fat) tissue Show up (dark grey)
• Limitations of CT


  • Time consuming and expensive
• Magnetic Resonance Imaging (MRI)


  • 4 Model uses magnetic forces
  • Detailed images of internal Structure
  • Machine Very Loud
  • Fat is lighter colour! Jone is darker
  • Expensive time consuming but very accurate
  • Associated with fat around the organs known as visceral fat

  
• Dual Energy X-ray Absorpitometry (DXA)


  • 3C model - fat mass, lean mass, Jone mass
  • Low dose radiation
  • Originally used for Jone density (BMD)
  • Whole-body Scans = body Composition
  • Lean mass not muscle mass
  • Abdominal fat not Visceral fat
• Dual Energy X-ray Absorpitometry (DXA)


  • Measuring Jone mineral density using spectral Imaging
  • Lines specifically drawn through landmarks (Eg. femoral neck, illac crest)
  • Regional scans with higher resolution (femoral neck and lumbar spine)
• Body Composition is influenced by:
• Anthropometry


  • The scientific study of the measurements and proportions of the human body
  • Waist and hip circumference

  
• Gynoid (Pear)


  • Typically found with women
  • Fat on hips/buttocks
  • Not associated with health risk factors
• Android (Apple)


  • Typically found with men
  • Risk for high BP, CVD diabetes and abnormal blood lipids
• Males are dominant in have more fat in the visceral area
• Visceral fat


  • Fat around the organs
  • More metabolically adverse (bad) than subcutaneous fat

  
• Subcutaneous Fat


  • Above muscle layer
  • Around the body on the outside
• Health is not determined by the amount of body fat alone but also by WHERE THE FAT Is LOCATED

  
• Adverse Molecules Secreted by Adipocytes


  • Fat is very active Endocrine organ and Secretes a whole bunch of negative related horomones, enzymes and factors
  • Adipokines
  • Enzymes
  • Growth Factors
  • Inflammatory Mediator's
  • Clotting Factors
• Increase in Cardiovascular disease, diabetes etc. can be caused by the Adverse Molecules Secreted by Adipocytes
• Visceral fat covers only 5-10 % of our body fat, we have more subcutaneous fat because we have more surface area for subcutaneous fat

  
• Visceral fat makes a small Contribution to TOTAL OBESITY, but a big contribution to obesity related diseases

  
• Liposuction


  • Use suction to remove fat in specific area's
  • Liposuction Does Not change Visceral fat
  • Fat will only be lost in subcutanous layer
• Visceral fat and Weight LOSS Through energy restriction and increased expenditure

  More VAT is lost compared to SAT

  
• Small reductions in weight are associated with risk reduction

  
• Obese with high waist circumference = High Risk

  
• Obesity in Canada gradually increasing from 14% in 1979 to 30% in 2015