What is the thermic effect of food/what are the components of energy output?
Our energy output - energy used in digestion, absorption, metabolism & storage of nutrients from food
**Metabolism (energy we use to breathe, regulate body temp, heart beat)
What is an example of food with a low energy density? How does this affect feeling of fullness?
Vegetables/high fiber foods!
Increases satiation & satiety
(foods that provide less kcal/gram of food consumed)
How much of the body’s total energy expenditure is represented by the Basal Metabolic Rate (BMR)?
60-70%
Which type of adipose tissue can be broken down faster for use in thermogenesis?
Brown adipose
Highest percentages in babies, in adults it depends on location/gender/BMI (usually adults in cold climates with healthy BMI)
In adipotoxicity, TNF-alpha, IL-6, and Resistin stimulate what process?
Lipolysis
What is lipotoxicity?
Accumulation of free fatty acids in non-adipose tissue
How do you diagnose someone with metabolic syndrome?
Need 3/5 components:
- low HDL
- high BP
- insulin resistance (>110)
- high triglycerides
- high waist circumference
If patient is on medications to regulate BP, they only need 2/5
What hormone controls hunger?
Ghrelin (controlled by hypothalamus)
How do energy from heat combustion, digestible energy, and metabolizable energy differ?
Metabolizable energy < Digestible energy < Energy from Heat combustion
What is the difference between appetite and hunger?
Appetite - desire to eat
Hunger - need to eat
What foods have a higher energy density? How does this affect the feeling of fullness?
Starchy foods, pizza, fructose
(foods that provide more kcal/g of food consumed)
Decrease satiation & satiety
**Strong satiety effect once it reaches the SI
What is the BMR (basal metabolic rate)?
Energy required to maintain life when body is at rest
What are the major factors affecting BMR?
Higher BMR: males, tall/thin people, PMS hormones, Caffeine, fever, stress, extreme temperatures
Decreased BMR: fatty tissue, old age
How much of the body’s TEE is represented by the Thermic affect of food (TEF)?
10%
What major factors affect TEF?
Meal composition:
- Proteins>Carbs>Lipids
- Spicy foods increase metabolism by 33% for 3 hours after meal
Meal timing - energy expenditure is raised 30-90 min after a meal
What is the difference between AT and NEAT?
AT = energy use during fitness exercise
NEAT = activities of daily living and energy expended during leisure activities (gum chewing)
What factors affect AT?
Body size
Fitness level
EPOC = Increased metabolic rate that occurs after exercise has ceased
What is the TEF of protein?
20-30% increased energy expendeture
What is the TEF of lipids?
0-5% increased E
What is the TEF of carbs?
5-10% increased E
What is the TEF in a mixed macronutrient meal?
10%
Describe the progression of positive energy balance in overnutrition.
- Fill glycogen stores
- Excess carbs turned into FA
- Dietary fat stored in adipocytes
- Less lipolysis
- Hypertrophy/Hyperplasia of adipocytes
What is the difference between hypertrophy and hyperplasia in relation to adipocytes?
Hypertrophy - increase in size of adipocytes
Max size = 1mcg of fat/cell
Hyperplasia - increase in number of adipocyres
T/F: Lipoprotein lipase is more active in obese individuals than lean individuals.
True
Where is lipoprotein lipase more active in males vs females?
Males - abdomen
Females - Breasts, hips, thighs
What is the difference between ‘apple’ and ‘pear’ shape?
Apple - MC in males, android-type obesity, more visceral fat, associated with more health risks
Pear - MC in females, gynoid-type obesity
What are the characteristics of white adipose (WAT)?
Unilocular adipocyte
Release FFA when needed
Visceral & subcutaneous
What are the characteristics of brown adipose (BAT)?
Multilocular adipocyte
Quick-access fuel for thermogenesis
High rates of active uncoupling proteins
What is beige fat?
ALL adipose tissue has genes for BAT that can be accessed via cold stimulus in subcutaneous WAT
T/F: BMI is a measure of body fat.
False - measure of appropriate weight based on height
What is the range for a healthy BMI?
18.5-24.9
What BMI is considered overweight?
25+
What BMI is considered severely thin?
<16
What are the 3 BMI categories for obesity?
Obese 1: 30-34.9
Obese 2: 35-39.9
Obese 3: 40+
What are 3 better indicators of health (instead of BMI)?
Waist circumference (WC)
Waist to hip ratio (WHR)
Waist to height ratio (WHtR)
What do you measure for a waist measurement?
Smallest part/halfway between iliac crest & bottom of lowest rib
What do you measure for a hip measurement?
Measured at largest part, standing, without tissue indentation
What is the healthy waist circumference?
Males - 40” or less
Females - 35” or less
What is the healthy WHR?
Males - 0.95” or less
Females - 0.80” or less
What is the healthy WHtR?
<0.5
What comprises fat mass?
Essential fat
Storage fat
What comprises fat-free mass/lean body mass?
Bone
Muscle
Fluid
T/F: Subcutaneous fat is easier to lose than visceral fat.
False!
Very metabolically active, Increases lipotoxicity due to increased LPL activity
What is the difference between adipotoxicity and lipotoxicity?
Adipotoxicity - Neg effects of storage of excess fat in adipose tissue
Lipotoxicity - Neg effects of storage of excess fat in non-adipose tissue
What adipokine causes insulin resistance?
TNF-alpha
Also promotes beta cell apoptosis & stimulates lipolysis
What adipokine protects against beta cell apoptosis?
IL-6
What adipokine inhibits insulin release from beta cells?
Leptin
**Leptin resistance seen in many obese people
Which adipokine is decreased in obesity?
Adiponectin
**Induces insulin sensitivity in muscle/adipose
Which adipokine is increased in obseity?
Resistin
**Decreases muscle ability to take up FA
How does the pancreas react to lipotoxicity?
beta cell failure
How does the liver react to lipotoxicity?
non-alcoholic fatty liver disease
How do the muscles react to lipotoxicity?
Insulin resistance (type 2 diabetes)
How does the heart react to lipotoxicity?
Heart disease
How is endothelium vasoconstriction affected by lipotoxicity?
HTN
What pathway is decreased in lipotoxicity?
Beta-oxidation
What are the pros/cons of using skinfold thickness to measure body composition?
Pros: Fast, inexpensive, noninvasive, user-friendly
Cons: less precise, only measures subcutaneous fat
What are the pros/cons of using underwater weighing to measure body comp?
Pros: fairly accurate
Cons: Expensive, some error in calculations for density
What are the pros/cons of using bioelectric impedance to measure body comp?
(Fat = poor conductor, muscle/organs = good conductors)
Pros: cheap, fast
Cons: less precise, more error, patient must be well hydrated, no caffeine/alcohol 24 hours prior, must not have exercised for 4-6 hours
What are the pros/cons of using air displacement?
Pros: quick, portable
Cons: expensive, less accurate than underwater weighing or DEXA
What are the pros/cons of using DEXA?
Pros: Accurate, reproducible, also determines bone density
Cons: expensive, requires training, x-ray exposure,
What are the pros/cons of using MRI?
Pros: accurate, reproducible
Cons: expensive, time consuming
What are the pros/cons of using waist circumference?
Pros: cheap, fast
Cons: More error/less precise