chapter 8: assessing body composition Flashcards
What is body composition?
The body is composed of fat mass and fat free mass
What is Fat Mass (FM)?
- All of the fat in the body
- Fats that can be extracted from the tissues in the body
- Can be called fat weight
What is Fat-Free Mass (FFM)?
- All fat-free tissues in the body including water (67% of FFM), muscles, bones, minerals, connective tissues, internal organs
- Can be called fat free weight
What is lean body mass? (LBM)
- Contains a small percentage of essentials fat stores
- Represents an in vivo entity that remains relatively constant in content of water, organic matter
What is the difference between LBM and FFM?
Fat free mass has no fat, LBM contains a small percentage of essential fats
What are the main categories of body fat?
Essential Fat and Nonessential Fat
Essential fat includes lipids in the:
- Nerves
- Heart
- Lungs
- Kidneys
- Intestines
- Bone marrow
- Brain
- Muscles
- Liver
- Spleen
- Mammary glands
- Lipid-rich tissues of the CNS
What are essential fats?
- Larger percentage in women: fat in breasts, uterus, etc., women have additional sex-specific essential fat
- Fat deposits are necessary for normal physiologic functioning in men and women
Where are non essential fats?
- Storage primarily found in fat cells (adipose tissue cells) either subcutaneously or vicerally
Adipose tissue contains about :
- 83% pure fat
- 15% water
- 2% protein
The amount of storage of fat depends on?
- Gender
- Age
- Heredity
- Metabolism
- Diet
- Activity level
Name the 2 Component Body Composition Models
- Skinfolds
- Hydrostatic Weighing (HW)
- Air Displacement Plethysmography (ADP)
What components do 2 component body composition models measure?
Fat component and Fat-Free Body component
Name 5 assumptions of the 2 component models of body composition
- Density of fat is 0.901 g/cm3
- Density of FFB is 1.100 g/cm3
- Densities of fat and FFB components (water,mineral, protein) are the same for all individuals
- Densities of various tissues composing FFB are constant within an individual and their proportional contribution to the lean component remains constant
- Individuals differ from the reference body ONLY in the amount of fat (73.8% water, 19.4% protein, 6.8% mineral)
These assumptions are not valid, the forst 2 differ for each individual and the last one can be affected simply by drinking water
Name the 3 component body composition models
- Bioelectrical Impedance Analysis (BIA)
- Dual Energy X-Ray Absorptiometry (DEXA)
What are the 3 components body composition measurements?
FM, FFM and component of fat free mass
Name the multiple component body composition models
- Computed Tomography (CT)
- Magnetic resonance Imaging (MRI)
Negative factor of CT
Ionized radiation (but measures fat distribution not just percentage)
FFB density varies with:
- Age, Growth, Sexual maturation, Gender, Ethnicity
- Levels of body fatness, physical activity level
- Number of diseases
FFB density depends on:
The relative proportion of water and mineral that compose the FFB
What are the Siri (1961) and Bozek et al. (1963) equations used to determine? What population would you use them on?
Estimation of % body fat, only to be used on caucasian males/females
Would you overestimate or underestimate your clients % BF if the FFB density was estimated to be greater than 1.100 g/cm3?
Underestimate
Would you overestimate or underestimate your clients % BF if the FFB density was estimated to be lower than 1.100 g/cm3?
Overestimated
Relative to the assumption of the 2 component model of body composition that FFB density is equal to 1.100 g/cm3, would you overestimate or underestimate the % BF for a black man or woman, a pro football player, a white child, or an elderly white man or woman?
- Overestimate the white child (lower mineral content and higher body water) and the elderly (lower mineral content)
- Underestimate the black man or woman and pro football player (higher mineral content and/or higher relative to body proteins)