Final (everything but MT2) Flashcards
what is the energy balance equation
output>input = negative balance; weight loss
input>output = positive balance; weight gain
What is energy input
calories that or body gets from foods we eat
what are the 3 main macronutrients that are sources of energy
4kcal/g for carbs
4kcal/g for protein
9kcal/g for fats
(alcohol can also be a source, @7kcal/g)
What are some factors that affect energy input
neuroendocrine factors (hormones, neurotransmitters, etc like leptin)
filling/distention of stomach
social/psychological factors
food availability/appeal
genetics
What happens when there is a lack of leptin?
sends satiety signals to stop eating; lack of leptin leads to weight gain
What is satiety
neural state that leads to stopping of food intake (things like loss of desire to eat, is the opposite of hunger)
What is hunger
physiological drive to eat
what is appetite
psychological desire to eat (more conditional than hunger)
What are some hormones that impact the energy balance
Leptin - lowers food intake
NPY (neuropeptide Y) - increases food intake
Ghrelin - increases food intake
PYY (peptide YY) - lowers food intake
CCK (cholecystokinin) - lowers food intake
apoA IV (apolipoprotein A4) - lowers food intake
How does the hypothalamus impact hormones and neural signals in relation to energy balance
is the central integrator of circulatory signals (hormones)
Describe the pathway of PYY
digestion of food stimulates PYY and CCK production, resulting in the hypothalamus lowering NPY activity to increase satiety
Describe the pathway of leptin
as nutrients are stored in fat cells, leptin release is stimulated that signals the hypothalamus to lower NPY activity
describe the pathway of ghrelin
an empty stomach secretes ghrelin, which signals to the hypothalamus to increase the activity of NPY, while the fat cells stop secreting leptin
What are the 3 ways energy is outputed
REE - resting energy expenditure (65% of total output, minimum calories used by the body to maintain homeostasis)
TEF - thermic effect of food (10%, acute rise in energy use after meal, influenced by the meal size and macronutrient composition)
PA - physical activity (25%, highly variable)
WHat is BMI
measure of weight (kg)/height (cm squared)
what are two ways to measure Bodyfat
skinfold thickness
underwater weight
WHat is lean body mass (LBM)
body muscle
what is fat free mass (FFM)
LBM + water/minerals
What are the BMI ranges?
under 18.5 - underweight
18.5-24.9 - normal (lowest mortality risk from 21-24)
25-29.9 - overweight
30-34.99 - obesity1
35-39.9 - obesity 2
over 40 - obesity 3
Why is there a large increase in obesity over the last few decades?
high availability of high energy foods
lower physical activity
how many canadians are overweight
1 in 3
how many canadians dont get enough exercise
8 in 10
WHat are the 2 circumference measurements
waist to hip ratio - good indicator of obesity and co-morbidities
waist circumference - if larger than 100cm for men and 90 cm for women, 50% of this population have health problems related to metabolic syndrome which is a combination of the following three
-atherogenic dyslipidemia (high cholesterol
-hypertension
-high blood glucose
What are the 2 types of fat
essential - around vital organs and breasts in women (3% in men, 12% in women)
Storage - non essential fat that can be mobilized for energy
How is fat distributed
visceral - intra abdominal and associated with metabolic syndrome (men usually have more)
Upper subcutaneous - (apple shaped, high waist-hip ratio)
lower subcutaneous- (pear shaped)
WHat are some health risks with obesity (BMI>30)
-type 2 diabetes
-hypertension
-heart disease & stroke
-cancer
-joint disease (e.g., knee)
-INFLAMMATION chronic low-level….contributes to increased risk of some cancer
WHat is white adipose tissue
fat/energy storage
what is brown adipose tissue
regulatory functions and energy balance (heat production)
how do adipocytes grow
hypertrophy and hyperplasia, with weight loss the cell size decreases but not the number
How is fat mobilized in the body
Hormone sensitive lipase mobilizes TG into Fatty acids in adipocytes, and lipoprotein lipase converts free floating TG into fatty acids , both for use in the muscles and cells as energy
WHat are the 3 components most strategies use to manage obesity
diet control
physical activity
behaviour (slow eating)
what are the general principles behind energy restricted diets
intake should be lower than output
adequate nutrient intake and physical activity should be ensured
should all be combined with lifestyle changes
WHat are some diet categories
-moderate calorie deficient (1200-1500)
-low calorie diet (1000-1100)
very low calorie diet (800) - only when BMI is above 32
the greater the caloric restriction, the greater risk of micronutrient deficiencies
What are some issues with FAD diets
unbalanced macronutrients
exclusion of major food group
micronutrient deficiencies
replacement of foods with supplements
lack of emphasis on physical activity
What are 4 complex interactions that can offset energy balance and promote obesity
psychology (social/individual)
food (production/consumption)
Physical activity (environment and individual)
Physiology