Body Composition Flashcards
What is Body Composition?
refers to makeup of tissues of the body-often used in reference to % body fat
What is the most common model to describe body composition?
two compartment model:
1. fat mass
2. fat free mass
In the Two-Compartment Model of Body Composition, is there more fat or fat-free mass?
more fat-free mass
The body is composed of:
- muscle
- bone
- fat mass (adipose tissue)
- organs
fat mass
- essential fat
- non-essential (storage fat)
essential fat:
- required for normal body function and metabolic fuel
- located in body marrow, heart, lungs, liver, spleen, kidneys, intestines, muscles, and CNS
- women: sex-characteristic fat related to childbearing
non-essential fat (storage fat)
- required for protection and insulation
- located around internal organs (internal storage fat)
- located below the skin (subcutaneous storage fat)
Functions of fat:
- insulation/cushioning
- stored energy (greatest capacity)
- structural (cell membrane)
- involved in nerve conduction (myelin sheath)
- critical for absorption of fat-soluble vitamins
- backbone for steroid hormones
essential fat is used to keep and maintain:
homeostasis/normal function
energy storage
- reliant on for reserve fuel when we do not have food quickly available to us, used for times when there would be a famine, etc.
- body still treats it as time of abundance and is storing extra for later, when that is not needed because we have food all the time
- body will treat candy as high-density nutrients because it has a higher number of calories (we consume for abundance)
structural
- fat cells involved in nerve conduction
- helps with transmission speed
- helps with fat-soluble vitamins
brain needs fat to survive:
- likes glucose as fuel bc its quick and efficient
- if someone has a concussion, new evidence says that they should eat fats right away
the brain is composed of ___% fat
more than 60%
Danger of excess adipose tissue
- curvilinear because there’s bad at both ends
- heart disease
- stroke
- arthritis
- hypertension
- gallstones
- diabetes
Dangers of minimal fat - malnutrition
- depression
- compromised immune system
- infection
- hormone dysregulation
- anemia
- hair loss
- pregnancy complications
- menstrual irregularities
- bone loss (osteoporosis)
When there is minimal fat, the body starts taking away form things it deems:
unnecessary to survive
Types of Fat Cells
- white adipocytes
- brown adipocytes
- beige adipocytes
White adipocytes
- most abundant
- primary role is to store fuel as lipid droplets
- stored as triglyceride
Brown adipocytes
- greater percent in infants and children than adults
- increase resting energy expenditure and generate heat
- contain large numbers of mitochondria
- get color from larger presence of mitochondria
Beige adipocytes
- function similar to brown adipocytes
- increased energy expenditure
- some ability to act as storage container and some to increase resting metabolism
- bridge between other two
Body Mass Index (BMI)
- most common technique in health care
- body mass index = mass (kg)/height (m^2)
- limitations: disregards proportion of fat mass vs fat free mass
Methods of Measuring Body Composition
- underwater weighing
- air displacement plethysmography
- dual energy x-ray absorptiometry (DEXA)
- bioelectrical impedance analysis (BIA)
- sum of skinfolds
Underwater weighing and Air Displacement Plethysmography
- both methods measure body density to estimate % body fat
- body divided into fat free and fat mass
- measurement of body composition
underwater weighing or air displacement plethysmography used to measure body volume - underwater weighing is gold standard unless you have a DEXA
Dual Energy X-ray Absorptiometry (DEXA)
- two x-ray beams are used to determine whole body and regional estimates of lean tissue, bone density, and fat
- SEE = 1.8%
- popular technique with several advantages
- disadvantages include expensive and certified medical personnel must perform the scan
- low error rate
- popular in osteoporosis studies
SEE means:
regression model line of best fit
Bioelectrical Impedance Analysis (BIA)
- estimation of body composition
- simple, fast technique
- small electrical current is applied to one extremity and the voltage drop is measured at another extremity
- lean tissue is a good conductor of electricity
- fat tissue is a poor conductor
- person’s hydration status can impact results
skinfold method
- prediction of body density from estimation of subcutaneous fat (20-70% of total fat)
- thickness of subcutaneous fat is measured
- specific sites on the body based on age, gender, and race
- body density is calculated using siri equation and % body fat calculated from body density
- SEE = 3.5%
As we age, in both sexes, we see a higher accumulation of:
adipose tissue
This structure is responsible for transmitting the AP deep into the muscle fiber
T-tubule
Explain the body composition assessment known as DEXA
- two x-ray beams are used to determine whole body and regional estimates of lean tissue, bone density, and fat
- multicomponent model
____ is defined as the amount of blood pumped by the heart each minute
cardiac output
Change in body macronutrient energy stores =
energy intake - energy expenditure
even though you burn a lower % of fat during high-intensity workout, is the amount burned in kcals the same as during a low-intensity workout?
yes, the idea that working at low-moderate intensity to burn the most fat is not true
As VO2 max increases, what becomes the primary fuel source?
carbs more than fats
cross over point in fuel utilization is when:
carbs overtake fats in dominant energy source
___% is the lactate threshold
60%
lactate threshold is the point where:
it switches to anaerobic
rapid decrease in fat oxidation during exercise is also due to the type of muscle fiber being recruited which is:
type II
Is there a large change in usage of plasma glucose during exercise?
no
What energy source during exercise has a large change?
muscle glycogen (stored glycogen)
More fat is called into play for:
long-duration exercises
Less CHO is used during long-duration exercises so that the brain:
still has fuel to function
Is CHO still being used during long-duration exercises?
yes, just not primary
at the beginning of exercise, lots of fuel is being pulled from:
stored glycogen
as activity goes on, stores components go lower and reliance on ____ goes up
blood glucose
High-intensity work will lead to:
- greater improvements in aerobic fitness
- reduction in cardiovascular disease
- improved sense of vigor
- the harder the workload, the more calories will be used, including from fat
- clients should train as hard as they can, within reason
If someone wants to lose fat, it would be better to have them do:
high-intensity exercises
rapid increase in frequency and duration of exercise before a client is ready can lead to:
orthopedic and cardiac complications
Is there an ideal intensity for fat loss?
high intensity workouts are preferable
optimal fat-free mass:
dependent on sport; i.e., endurance vs strength type sports, weight category events
Optimizing fat-free mass:
- resistance training
- nutrition
- drugs
Hazards of too low relative body fat
- menstrual dysfunction
- disordered eating/eating disorders
- bone mineral disorders
- dehydration
- chronic fatigue / chronic fatigue syndrom
Cultural complications with idealizing low body weight:
- obsession with being thin
- self-esteem across age and gender
obsession with being thin versus:
- enjoying activity
- aiming to be healthy
self-esteem across age and gender
- eating disorders
- body dissatisfaction has been high among females
- body dissatisfaction is now high among males
Female Athlete Triad aka Relative Energy Deficiency (RED-S)
- Energy deficiency with or without disordered eating
- Menstrual disturbances / amenorrhea
- Bone loss / osteoporosis
