10
Evaluation
TOP 10 TAKEAWAY MESSAGES:
Obesity and Body Composition
1. Lean body mass is total body mass less stored fat in adipose
tissue (i.e., lean body mass = water, mineral, protein, glycogen,
essential organ fat).
2. In lean individuals, approximately 60% of body weight is water
(i.e., water is 75% weight of muscle and body organs). In those
with obesity, water weight can be as low as 40% body weight.
3. Ash weight of bone contributes a minor amount to total body
weight (~3 to 10 pounds).
4. Percent body fat mass is highly variable, and may range from
<5% to >70%.
5. Percent body fat mass is dependent upon both fat and muscle
mass.
6. Methods to measure body composition vary regarding accuracy,
reproducibility, expense, and accessibility.
7. Some DXA scans can measure percent body fat, android fat
(abdominal subcutaneous and visceral fat), lean body mass, and
bone mineral density.
8. Skinfold calipers are an inexpensive method to estimate percent
body fat but are user dependent and can be inaccurate in those
with obesity.
9. Bioelectrical impedance is a hydration-dependent body
composition assessment procedure; reasonable assessment of
android fat may best be achieved via a complementary tape-
measured WC.
10. Air displacement assessment of percent body fat is clothing and
hydration dependent; reasonable assessment of android fat may
best be achieved via a complementary tape-measured WC.
Body Composition
Two
Compartment
Three
Compartment
Four
Compartment Six Compartment
• Fat mass
• Fat-f ree
mass (water,
protein, bone
mineral, non-
bone mineral)
• Fat mass
• Lean mass
(water,
protein)
• Bone mass
• Fat mass
• Total body
water
• Protein
• Bone
mineral
• Fat mass
• Total body water
• Bone mineral
• Non-bone mineral
• Protein
• Glycogen
