Body Composition Flashcards
(51 cards)
Why is measuring body composition important?
Health status indicator, optimal performance, monitor changes (growth, aging, disease), evaluate treatment efficacy. Excess fat is associated with many diseases.
Define Fat Mass (FM) and Fat-Free Mass (FFM).
- FM: all extractable lipids.
- FFM: lipid-free chemicals and tissues
Define Essential Lipids and Lean Body Mass (LBM).
Essential Lipids: compound lipids (phospholipids) for cell membrane formation. LBM: FFM + essential lipids.
Define Relative Body Fat (%BF)
FM expressed as a % of total body weight
How does essential fat differ between males and females?
Females = 12%, Males = 3%. Too little fat can be detrimental to health because essential fat is important for organ function
What aspects of body composition are important to consider when measuring?
Total amount/proportion, location, and “quality”.
What is visceral fat and how can it be measured?
Visceral fat can be measured with CT scan or MRI and is associated with risk of diabetes
List the body composition techniques discussed.
Bioelectrical Impedance Analysis (BIA), Duel X-ray Absorptiometry (DXA), Computed Tomography (CT), Magnetic Resonance Imaging (MRI), Body Mass Index (BMI), Waist Circumference (WC), Waist-to-Hip Ratio (WHR)
How does Bioelectrical Impedance Analysis (BIA) work?
Chemical approach. Tissues have different impedance (resistance) to electrical current. More water = less resistance. Fat = less water, Muscle & “other” = more water
What outputs does BIA provide?
% body fat, some measure Total Body Water (TBW)
What are the benefits of using BIA?
Inexpensive, safe, portable, easy to use, 2 or 3 compartment model.
What are the weaknesses of BIA?
Low accuracy/validity, typically underestimates BF%. Many things can interfere with a “good signal” like hydration status, temperature, limbs touching
How does Duel X-ray Absorptiometry (DXA) work?
Two sources of low dose X-ray radiation pass through the body
What outputs does DXA provide?
FM + FFM + BM, total and regional FM content
What are the benefits of using DXA?
“Gold standard” for bone mineral content, non-invasive, quick, regional body composition, highly reliable/valid, 3 compartment model
What are the weaknesses of DXA?
Expensive, large equipment, not portable, requires trained technician, cannot measure intra-abdominal fat (some formulas exist to estimate it).
How does Computed Tomography (CT) work?
Anatomical approach. Rotating X-ray
What output does CT provide?
3D image of internal structures
What are the benefits of using CT?
Highly reliable/valid, important for disease management (e.g., cancer), 4 compartment model. It can separate fat (visceral vs subcutaneous), bone, muscle mass, and othe
What are the weaknesses of using CT?
Expensive, large, requires a trained technician, high dose radiation exposure.
How does Magnetic Resonance Imaging (MRI) work?
MRI uses magnets and radio waves to produce images on a computer. MRI does not use ionizing radiation
Anatomical approach. Big rotating magnet.
What output does MRI provide?
3D image of internal structures
What are the benefits of using MRI?
No radiation, highly reliable/ valid, important for disease management (e.g., cancer), 4 compartment model. It can separate fat (visceral vs subcutaneous), bone, muscle mass, and other
What are the weaknesses of using MRI?
Expensive, large, requires a trained technician, claustrophobia
