Chapter 7 Part 3

fat location affects…

health risk

visceral fat

android; greater health risk and easier to mobilize, floods liver and increases blood lipids

subcutaneous fat

gynoid; less of a health risk and harder to mobilize

android obesity

apple shaped

gynoid obesity

pear shaped

high subcutaneous, low visceral

low aortic plaque, less CVD

high visceral low subcutaneous

high aortic plaque, more CVD

energy expenditure can be measured with..

direct calorimetry, indirect calorimetry, doubly labeled water dilution method

direct calorimetry

heat given off when placed in chamber; expensive and impractical

indirect calorimetry

oxygen use and CO2 production; not practical in free living individuals

doubly labeled water - dilution method

ingest isotopes of oxygen and hydrogen; more practical and preferred in clinics, can measure TEE for up to 2 weeks

predictive equations

used for determining individual energy recommendations per day; DRI, mifflin st jeor, world health organization

DRI

estimated energy requirement; amount of energy recommended by DRI to maintain body weight in healthy individual

EER takes into account

age, gender, size, activity level; different equations used for men and women and different BMI groups

EER equation is used for BMI ranging from

18.5 to 25

TEE equation is used for BMI greater than

25

EER increases with

weight gain and increased physical activity

EER decreases with

advanced age and sedentary activity

if equipment is not available to estimate energy needs..

then predictive equations can be used

up to _ of variation in BMI between individuals attributed to genes (genetics/nature)

75%; genes that regulate body fat and responsible for proteins that affect energy intake, expenditure

risk for obesity no parents who have it

about 10%

risk for obesity 1 parent who has it

about 40%

risk for obesity 2 parents who have it

about 80%

influence of genes on body weight

twin pairs gain same amount of wait and lost same amount of fat; variation in weight gain between sets of twins

up to _ of variation in BMI linked to environment (environment/nurture)

25%

body weight tends to remain..

constant for long periods

set point

level of body weight that resists change

hypothalamus

region of brain that regulates satiety and energy expenditure; affected by hormones and nutrient signals

laboratory animals resist overfeeding by..

altering voluntary food intake

evolutionary advantage to maintain energy balance

fire, weaponry, and society protect humans from predators; upper threshold of BMI increases

too lean

increased risk of starvation

excess fat storage

increased risk of predation

short term regulation hormones

ginrelin, cholecystokinin, peptide yy

ginrelin

peptide hormone produced in stomach that stimulates food intake and hunger prior to meals; levels elevated for 1-2 hours prior to meal and decrease after consumed

cholecystokinin

released by small intestine when chyme enters; responsible for delaying stomach emptying and signals when to stop eating

peptide yy

hormone released from GI tract and signals reduction in appetite; amount of peptide yy released is proportional to amount of calories in a meal

long term regulation hormones

insulin and leptin

insulin

produced/released by pancreas in response to elevated blood glucose; proportional to body fat and interacts with hypothalamus to decrease food intake/body weight. influences amount of leptin produced/secreted

leptin

hormone made in adipose cells and interacts with hypothalamus to influence energy intake/expenditure; increases and decreases in blood as adipocytes

leptin regulating body fat

lack of leptin better at preventing weight loss than leptin is at preventing weight gain; defense against starvation stronger against defense against obesity

leptin deficient mouse

lack of leptin increases weight gain and appetite

leptin deficient mouse given leptin

leptin prevents/reverses weight gain

why weight gain can occur easily

thrifty metabolism, adaptive thermogenesis

thrifty metabolism

energy is conserved instead of expended, leading to more weight gain

pima indians

genetic predisposition to obesity but counteracted by increased energy expenditure

mexico pima

worked in agriculture and have lower BMI

arizona pima

sedentary lifestyle and consume energy dense foods; higher BMI

adaptive thermogenesis

change in energy expenditure that occurs due to change in body temp, trauma, and food intake

futile cycling - metabolic dysregulation

wastes energy by allowing opposing biochemical reactions to occur at same time; glycolysis and gluconeogenesis occurring at same time

brown adipose tissue

fat tissue that has more mitochondria than white adipose tissue; increased in cold exposure, infancy, hibernating animals

in brown adipose tissue, ETC is

separated from mitochondria and generates heat

low levels of brown adipose tissue=

high BMI and body fat

some individuals may gain weight easily because

they expend less energy in activity due to genetics