body composition concept and utility
TRANSCRIPT
Body CompositionConcept and Utility
ByDr. Majid Abi Saab
Consultant RheumatologistAl Ahli Hospital
QA
Body Composition
Most methods consider body having two components:
• fat component, i.e. fat mass• fat-free component, i.e. fat-free mass (FFM)Body fat %• average values: women, ~25%; men ~15%• minimal values: women, 8-12%; men – 5%• considered obese: women, >30%; men >20%essential and non-essential fat
Reference body composition for man
Reference body composition for women
Ratings of % Fat (ages 20-29 yr)
Rating Men Women Excellent 6-9 10-17 Good 10-14 17-21 Acceptable 15-19 21-25 Too Fat 20-22 27-32 Obese >22 >32
Determining Ideal Body WeightIndirect approachesMetropolitan height–weight tablesbody mass index (BMI)• weight (kg) / height2 (m2)• ideal range is 18-25• >30 considered obese
Direct approaches• hydrostatic (underwater) weighing• anthropometric (skin-fold) measurements• bioelectrical impedance analysis (BIA)• air-displacement plethysmography (BOD POD volume)• DEXA The Most Accurate
X Y
x y
Bioelectrical Impedance
GE Lunar DEXA Body compositionFDA approved the LUNAR DEXA for Body Composition
Indications for use: The GE Lunar Body Composition“…management of diseases/conditions where the disease/condition itself, or it's treatment, can affect the relative amounts of patient fat and lean tissue. “Main indications: Obesity | Metabolic Syndrome | Chronic Steroids treatment | Back pain related android obesity.“Some of other diseases/conditions for which body composition values are useful include chronic renal failure, anorexia nervosa, AIDS/HIV and cystic fibrosis.
X-ray Source
X ray Absorption
Bone has a Higher X Ray Attenuation than Soft Tissue
DEXA PhysicsXray attenuation is depending on the amount, type of tissue and energy level
Bone
Soft Tissue
Low Energy High Energy keV
Abs(HE keV) = Abs(HE keV) ST + Abs(HE keV) BAbs(LE keV) = Abs(LE keV) sT + Abs(LE keV) B
Abs(HE keV) = Abs(HE keV) ST + Abs(HE keV) BI(HE keV) = Io exp(µHE.ST DST + µHE.B DB)
Abs(LE keV) = Abs(LE keV) ST + Abs(LE keV) BI(38keV) = Io exp(µLE.ST DST + µLE.B DB)
Abs
DST ; DB could be calculated and so MB =DB x AreaB
MST = DST x AreaST
Measure Bone/Fat/Lean Using DXA
-3Compartment model Define anatomical region Define bone area (green pixel) Calculate Bone mass using two energies Outside of bone region, R-value -> %Fat
using two energies Use local uniform composition over Bone
region to calculate total soft tissue and after fat - lean in each sub-regions
Calculate Total weight by summing up Fat, Lean and Bone masses for all sub-regions
Obesity Female (42years) (Height: 162 cm / Tissue (kg) (Fat +
Lean): 96,2 to 93kg)A/G decrease : DECREASE fat in android!
Fat (kg): 49,9 to 44,6 to 45,7 / Lean (kg): 46,2 to 47,4 to 47,3kg
Normal Weight Obese Syndrome Female (26 years) (Height: 158 cm / Total Mass (kg) : 54,8 to
52,3kg)Follow up case over 1,5 year
BMI from 22,2 to 21,2 (normal)
Normal Weight Obese SyndromeFemale (26 / H:158 cm / W:54,8 to 52,3kg) Tissue (kg) (FM + LM): 52,7kg to 50,2kg
What did she lose over 1,5 year, Fat and/or Lean?Fat (kg): 18,9 to 16,5 / Lean (kg): 33,7kg to 33,7kg
Ask yourself• Are you Obese?• Do you suffer from Obesity related disorders?
• Metabolic?• Chronic Back Pain, Knee/Hip OA?
• Do you have difficulties on making regular/sport activities?
• Is your HAQ within normal?
Weight Management
• diet modification• physical activity modification• behavior modification
Principles Common to Successful Programs
Weight Managementbased on Energy Expenditure (kcal/min) Activity 56 kg 83 kg
basketball 7.3 11.5
Circuit training 9.8 15.4
Cycling (9.4 mph) 5.6 8.3
Running (9 min/mile) 10.8 16.0
Running (7 min/mile) 13.3 18.5
Swimming (slow) 7.2 10.6
Swimming (fast) 8.7 12.9
Tennis (singles) 6.1 9.0
Walking (3.0 mph) 4.5 6.6
Sitting (quietly) 1.2 1.7
Weight Managementbased on Intake
Weight change = Calories (energy) intake – energy expenditure
Energy Intakecaloric density• CHO = 4 kcal/g• protein = 4 kcal/g• fat = 9 kcal/g• ethanol = 7 kcal/ginfluence of diet composition
Effects of low-energy intake on
RMR
Bray, Lancet, 1969
Your are offered a tiny part of Snicker’s candy bar.
It contains 6 g of fat and there is 100 kcal of energy.
What is the percentage of energy that comes from fat?
a. 6 kcalb. 600 kcalc. 6%d. 54%e. 60%f. cannot be determined
Weight ManagementCalculate % Intake from Fat Breakfast - McDonald's
Total Energy (kcal)
Fat (g)
Sausage McMuffin w/Egg 517 33
1% Milk - 8 oz 110 2
Hash Brown Potatoes 125 7
Lunch - Burger King
Bacon Double Cheeseburger 510 31
French Fries - regular 227 13
Chocolate Shake - 10 oz 374 11
Snack
Snicker's Candy Bar 280 13
Dinner - Taco Bell
Two Tacos 372 16
Combination Burrito 404 16
Pepsi - 24 oz 288 0
TOTAL (40% of intake from fat) 3,207 142
Weight ManagementBehavior Modification• avoid automatic eating• plan meals ahead of time• don’t serve self more food than should eat• avoid social binges• practice other stress management techniques• set realistic goals• incorporate physical activity into program
Thank you for sharing