Body Composition

Question 1

Bioimpedence impedance analysis
1.function
2. impedance of diff tissues
3. Factors influencing result

Answer 1

1. diff tissues have diff electric impedances, run small current through body and determine body comp through amt impedance
2. bone (impermeable) > fat > muscle
3. dehydration, eating, exercise give + or - 5 kg

Question 2

Bioimpedance Spectroscopy
1. function
2. BIS v. BIA

Answer 2

1. non-invasive, measure resistance of flow of low strength currents throughout body
2. BIA uses single freq and measures total body water, BIS use multiple freq to measure TBW, differentiate b/w inter/extracellar water to est body cell mass

Question 3

1. Electrical impedance myography
2. 3D body scanners

Answer 3

1. localized electric current applied to muscle/muscle group to examine muscle
2. use expensive infrared depth sensors to find body comp, multiple applications

Question 4

Multi component models
1. Overview
2. Two comp model
3. Three comp model
4. Devices

Answer 4

1. split body into meaningful comp to study, fat mass associated with risk/disease
2. two comp model (trad), body weight = FFM + FM
3. three comp model, body weight = FFDM + FM + TBW
4. use same brands/devices throughout research experiments to minimize instrument variability

Question 5

1. Changes in body density
2. body comp differences and sex

Answer 5

1. not sex diff in childhood, increase in body density after age 12, plateau at 14 for females, males decrease % fat
2. males have greater body density, females have greater fat %

Question 6

1. Stages of adipogenesis
2. White adipose tissue
3. Brown adipose tissue

Answer 6

1. stage 1 embryonic adiphoblast, stage 2 precursor preadipocyte, stage 3 small adipocytes with adipose tissue and hormones, stage 4 mature adipocytes post birth
2. predom fat in adults, maj subcutaneous, visceral protects organs, cushioning, and insulation
3. mostly in fetus and infant, more mitochondria produce more ATP and heat (non-shivering thermogenesis) since babies lose heat faster due to smaller size

Question 7

White adipose tissue
1. Prenatal
2. Newborn
3. Postnatal

Answer 7

1. 14 weeks gestation, white adipose cells visible, 23 rapid hyperplasia leading to weight gain
2. 5 billion adipocyte storing E for extra-uterine life; normal to lose 1-2 lbs after birth
3. 30-50 billion, from age 1-8 increase, doubles during puberty, and plateaus during adulthood but can be increased with overconsumption of calories

Question 8

Preventing childhood obesity:
1. Steps per day
2. 4 things families can do

Answer 8

1. decrease with age, BMI, and television, increase with income
2. model healthy eating patterns, move as a family, consistent sleep routine, decrease screen time by increasing family time

Question 9

Levels of body composition models

Answer 9

1. atomic level: 95% CHON and 4.5% minerals like Na, K, P, Cl, Ca, Mg, S
2. molecular: water, lipids, PRO, and minerals
3. cellular: focus of study of growth is the sum of specific tissues
4. whole body: body size, physique, body vol and density, and body fat

Question 10

subcutaneous tissue:
1. hair
2. epidermis
3. dermis
4. subcutaneous tissue
5. visceral adipose

Answer 10

1. insulation, protects sensitive areas from debris
2. skin, barrier against external environment
3. CT, thermoregulation, sensation
4. fat, insulation, cushioning, E store
5. lines organs

Question 11

Subcutaneous tissue distribution and age

Answer 11

body fat decrease with age until 70:
1. decrease in face, hands, and feet
2. increase in thighs, waist, and abdomen

Question 12

body circumference measurement
1. Purpose
2. Method
3. advantage
4. disadvantage

Answer 12

1. shape of body provide body fat estimation
2. use flexible tape measure around neck, waist, and hips
3. cheap, easy, portable
4. vague estimate since it does not account for fat v. muscle

Question 13

DEXA
1. Purpose
2. Method
3. advantage
4. disadvantage

Answer 13

1. estimate body fat %
2. supine for 10 mins, X-rays of 2 diff E to measure
3. accurate and detailed data, low rad for bone density
4. not ideal for measuring body fat, high cost and experience req

Question 14

hydrostatic weighing
1. Purpose
2. Method
3. disadvantage

Answer 14

1. body comp
2. diff tissues have diff densities, comp out of water density with underwater density to determine body comp
3. not ideal for young children or those who are uncomfortable with being submerged

Question 15

bod pod
1. Purpose
2. Method

Answer 15

1. measure weight and vol to find body density and % body fat
2. sit inside pod for 3 mins, use air pressure changes to determine body comp