Studied by 3 people
What factors affect body weight?
-family history -personal weight history -healthy lifestyle contribution
is people being underweight or obese generally an issue in Canada?
no - being underweight is not much of a widespread problem, but obesity on the other hand is an escalating epidemic
Canadian rates of obesity
-26.9% of Canadians are obese; 1 in 4 adults clinically obese -1 of every 3 children is overweight or obese -BC has some of the lowest obesity rates in Canada -Saskatchewan, Manitoba and territories have highest rates of obesity in Canada
at what BMI are individuals considered clinically obese? overweight?
-obese: BMI = 30+ -overweight: BMI = 25-29.9
what is a major drawback to using BMI?
takes height and weight into account but does not account for body composition of the individual (i.e. higher BMI does not necessarily mean more fat - could also be due to having more muscle) - BMI does not account for amount or location of body fat
What are some of the risks associated with being underweight?
-famine/siege -hospital stays -wasting disease -cancer -heart disease
what are some risks associated with being overweight?
-chronic disease (hypertension, heart disease, diabetes) -obesity itself also declared as chronic disease
is there a simple fix to the obesity epidemic? why/why not?
no - obesity is a complicated issue that can be caused by many different factors besides diet and exercise (stress, sleep, etc.)
visceral fat
-fat that accumulates within the abdominal cavity -fat readily released into the bloodstream -increases risk of death from all causes
subcutaneous fat
-fat that accumulates just below the skin surface -does not have as many associated health risks as visceral fat
"apple" vs "pear" body shapes
-apple - more visceral fat; has more health risks associated because fat held more viscerally -pear - more subcutaneous fat
factors affecting body fat distribution (i.e. visceral vs. subcutaneous)
-menopause (e.g. follows more male-like distribution after menopause - more visceral fat after menopause) -smoking -alcohol intake (increases visceral fat stores) -physical activity vs inactivity
are there more risk factors associated with male or female obesity at a given BMI?
more health risks associated with male obesity because males have more visceral fat for a given BMI
health risks of obesity
-BMI -waist circumference -disease risk profile
waist circumferences that are considered "obese"?
men - greater than 102 cm (40 in) women - greater than 88 cm (35 in)
body mass index (BMI)
-general guidelines to evaluate the health risks of an individual -takes both height and weight into account (but not body composition)
what measures are used to diagnose someone as clinically obese?
BMI and a measure of body composition (e.g. MRI) and fat distribution (e.g. skin folds for subcutaneous fat)
what happens when we take in and produce more calories than we burn?
excess stored as fat
basal metabolism
-minimum energy expended to keep resting awake body alive -accounts for 60-70% of body's total energy needs -includes energy required to maintain heartbeat, respiration, and body temperature -amount of energy required for basal metabolism varies from person to person -approx. 1 kcal/min
metabolic activity of white fat tissue vs lean tissue
-white fat tissue is inert and does not require a lot of energy to maintain -lean tissue is more metabolically active -person with more lean tissue will have greater level of basal metabolic activity than someone with greater proportion of fat mass
effect of physical activity on energy expenditure
-more physical activity leads to greater energy expenditure (more activity = more energy burned) -lack of activity is a major cause of obesity
thermic effect of food
-energy used to digest, absorb and metabolize food nutrients -~5-10% above total calories consumed
thermic effect of food is highest for which macronutrients? lowest?
-TEF highest for proteins so costs us the most to digest and absorb proteins; proteins give us the feeling of fullness for longest too -TEF lowest for fats -carbs have intermediate TEF
adaptive thermogenesis
non voluntary physical activity - e.g. maintenance of muscle tone, maintenance of posture, fidgeting/shivering
basic estimate of resting energy expenditure. what does this estimate not take into account
-women: (weight in pounds)*10 -men: (weight in pounds)*11 -doesn't take activity into account
hunger
-physiological need -occurs approx. 4-6 hours after eating -triggered by contracting empty stomach, empty small intestine, grehlin (stomach hormone), chemical/nervous signals in brain
appetite
-psychological need -appetite can override hunger -leads to over-eating
what factors cause us to/occur when we are seeking food and starting a meal?
sensory influences - sight, smell, thought, sound and taste of food heighten appetite
what factors determine if we keep eating?
cognitive influences: -social stimulation (presence of others) -perception of hunger vs awareness of fullness -special foods (foods with special meaning, favourite foods) -time of day -abundance of available food
postingestive influences (i.e. after food enters digestive tract) on satiety
-food in stomach triggers stretch receptors -nutrients in small intestine elicit nervous and hormonal signals informing brain of fed state
post absorptive influences (i.e. after nutrients enter blood) on hunger/satiety
-nutrients in blood signal brain (via nerves and hormones) about their availability, use and storage -satiety dwindles as nutrients dwindle -> hunger develops
satiation
-stomach (stretch receptors), small intestine (nutrient absorption), brain (hypothalamus) involved in satiation (all send signals to brain to stop eating) -involves receptor nerves and hormones
satiety
-perception of fullness (psychological) -hunger signals always outweighs satiety in the appetite control system
what macronutrient is the most satiating?
protein
what macronutrient(s)/foods result(s) in feeling of fullness?
-fats and proteins slow gastric emptying -> feeling of fullness -foods high in dietary fibre, water and foods puffed up with air
what causes obesity?
there are many different reasons why someone might deal with obesity including: -enzyme theory (more LPL enzyme = fat cells store lipids more easily -> body will remain obese) -fat cell number theory (body fatness determined by number and size of fat cells) -set-point theory (body chooses weight it wants to maintain and regulates activity and behaviours to do so) -thermogenesis/brown fat theory (person with more brown fat (and brown fat is very metabolically active) will have more energy-wasting proteins so will stay leaner) -adaptive thermogenesis theory (genetic inheritance determines efficiency of system that balances between giving off fuel as heat when in excess and conserving energy when energy supplies are low) -diet-induced thermogenesis theory (differences in energy expenditure immediately after eating a meal in lean people vs obese people may account for differences in accumulating body fat)
do genetics influence person's tendency to become obese?
-genetic inheritance strongly influences a person's tendency to become obese - lifestyle choices then determine whether that tendency is realized
what are some external cues that are involved in obesity?
-external cues to overeating such as: available foods (food pricing, availability and advertising), stress and human sensations -physical inactivity - screen time has replaced work and play outside
what may cause a 1-2 pound change in body weight?
-change in body fat -shift in body fluid content, bone minerals and lean tissue -contents in bladder or digestive tract -body weight can change/fluctuate at different times of the day
benefits of exercise
-increases energy expenditure -helps with weight management -preservation of lean tissue -increased epinephrine and NE to increase fat mobilization -increase fat utilization -may lead to increased resting metabolic rate after exercise and prevent decrease in resting metabolic rate from dieting
is gradual or quick weight loss preferred? why/why not?
gradual weight loss preferred in order to spare lean tissue but still lose fat
fasting: early and later deprivation
-early deprivation: first use glucose (so break down all glycogen) -> once glycogen is depleted start to break down proteins (use fat last) which can be converted into glucose; nervous system cannot use fat as fuel and fat cannot be converted to glucose -later deprivation: ketone bodies help feed nervous system so helps spare tissue protein
infectious diseases
-caused by bacteria, viruses, parasites or other microbes (something invading our body) -e.g. tuberculosis, influenza, polio
Degenerative diseases
-chronic -irreversible -due to personal life choices (smoking, diet, alcohol, lack of physical activity) -leading cause of death in Canada
How does malnutrition affect us in terms of disease?
-nutrient deficiencies or excesses of nutrients can impair the immune system -malnutrition worsens disease and disease worsens malnutrition -undernutrition makes skin thinner with less connective tissue, so weakens skin protective barrier and delays skin antigen sensitivity -undernutrition can lead to less immune cells and antibodies being released/produced -undernutrition can lead to reduction in size of immune system organs -overall invader kill time takes longer, circulating immune cells are reduced and immune response is impaired
excess of what nutrients can impair immune system?
zinc and iron toxicities can impair immune system
deficiencies of what nutrients impair immunity?
-energy and protein deficiencies -fat-soluble vitamins (K, A, D, E) -B vitamins (especially folate) -vitamin C -minerals: iron, zinc, selenium, copper, magnesium
main root/cause of cardiovascular diseases
-mostly all involve atheroscelrosis (hardening of arteries caused by plaques) -atherosclerosis formed by body's inflammatory response to tissue damage and/or diet high in saturated fat -atherosclerosis plaques in artery's inner wall reduces blood flow --> clots can also enter area and become trapped (because artery diameter is smaller) and cause tissue death
causes of atherosclerosis plaque development
damage caused by: -high LDL cholesterol -hypertension -toxins from cigarette smoking -elevated homocysteine levels in blood -viral/bacterial infections
thrombus
stationary blood clot
thromobosis
large blood clot that blocks off a blood vessel
embolus
clot that breaks free
embolism
clot that becomes stuck
Non-modifiable risk factors for cardiovascular disease
-older age -male -family history of heart disease
diet considerations to reduce risk of cardiovascular disease
-controlling dietary lipids (reduce saturated and trans fat so that they make up no more than 10% of daily calories) -limit dietary cholesterol (no more than 300 mg per day) -diet rich in omega-3 fatty acids -eat fish, fruits, vegetables, milk products and whole grains -consume fiber, nutrients and phytochemicals (found in whole foods - supplements are ineffective) -benefits found in drinking 1-2 drinks per day to raise HDL and reduce risk of blood clots (lowers risk of blood clots)
hypertension
-no symptoms that you can feel -one of the most prevalent forms of cardiovascular disease
what does systolic vs diastolic pressure represent?
-systolic pressure = ventricular contraction -diastolic pressure = ventricular relaxation
Lifestyle/nutrition changes for hypertension
-lose weight if overweight (losing 10 lbs can significantly lower blood pressure) -physical activity can lower blood pressure for up to 12 hours after exercise -control salt/sodium intake (direct relationship between salt intake and blood pressure - some people more sensitive than others) -consuming alcohol in high doses increases blood pressure -prevent/correct hypertension by intaking adequate amounts of vitamin C, magnesium, potassium, and calcium
effect of alcohol on blood pressure (when consumed in large amounts vs small amounts)
-can increase blood pressure when consumed in high doses -can lower risk of blood clots and raise HDL by drinking 1-2 drinks per day
what nutrients/minerals can help prevent or correct hypertension when ingested in adequate amounts?
-calcium -potassium -vitamin C -magnesium
what groups of people are more sensitive to salt in the diet?
-people of African descent -people with family history of hypertension -older people -people with kidney problems -diabetes
how can we improve salt sensitivity?
taking in potassium
what lifestyle choices influence cancer risk?
-physical activity is a protective factor -smoking increases risk -diet: reduced caloric intake can help prevent cancer (caloric effect)
what diet choices can affect cancer risk?
-reduced caloric intake can help prevent cancer (caloric effect) -greater cancer risk with greater BMI -fats and fatty acids promote cancer -alcohol strongly correlated to head and neck cancers -diets high in red meat related to increased cancer risk -acrylamide (found in potatoes cooked at high temperatures) has carcinogenic effect -people with diets high in fibre and with adequate fluid intake have lower incidence of cancers -folate deficiency linked with cervical and colon cancer -high calcium intake linked with colon cancer prevention -high iron intake associated with colon cancer -phytochemicals are antycarcinogens
Effects of alcohol (begin after just 1-2 drinks)
-impairs balance -impairs motor coordination -impairs decision making -impairs memory
alcohol nutrient content
-made from carbohydrates -alcohol is an energy source -gives us 7 kcal of energy
what is the biggest age group that makes up alcohol drinkers?
people in their 20s
what factor has been said to have the biggest influence on whether someone will drink?
influence of their parents - children usually adapt their parents' attitude towards alcohol
in what age group is there the greatest percentage of alcohol dependence?
-18-20 and 21-24 -starting to shift to slightly older ages (especially in females )
absorption of alcohol in our body
-absorbed rapidly via simple diffusion (can be absorbed in less than a minute if drinking on empty stomach) -depends on rate of stomach emptying -found wherever water is found in body -easily moves through cell membranes (but damages them in process)
what alcohol is absorbed the fastest? slowest?
-wine is absorbed the fastest -beer is absorbed the slowest -hard liquor absorbed slower than wine, but faster than beer
how does having a full vs empty stomach affect alcohol absoroption
-having food in the stomach slows/decreases absorption of alcohol (since when food is in stomach less alcohol hits the side of the stomach so less is absorbed) -alcohol absorbed very quickly on empty stomach (can be absorbed in up to 1 minute)
alcohol metabolism
-metabolized by liver -metabolized by alcohol dehydrogenase and aldehyde dehydrogenase - turn alcohol into CO2 and water -alcohol cannot be stored so has to be cleared and metabolized -metabolism of alcohol is prioritized since it is a poison/toxin (so everything else has to be wait to be metabolized until liver has a metabolized alcohol -alcohol metabolism depends on sex, ethnicity, food, physical condition, alcohol content and experience with alcohol
why are breathalyzers used?
alcohol can be excreted through the lungs - use 2100:1 ratio to convert alcohol content in breath to amount of alcohol in blood
microsomal ethanol oxidizing system (MEOS)
-in liver -important in dealing with alcohol
do genetics affect alcohol metabolism?
-yes - people have variations in ALDH and ADH -impacts how much somebody can drink -fast ADH and slow ALDH leads to accumulation of acetaldehyde which leads to a lot of negative side effects associated with drinking
potential benefits of moderate alcohol intake (1-2 drinks)
-increase HDL -decrease chronic inflammation -improves body use of glucagon and insulin -improves cognitive function -wines and some beer have good phytochemical content ***although alcohol can do these things, all of these positive effects can be obtained through living a healthy lifestyle (exercise, good eating habits) without the possible negative effects that may be associated with alcohol
negatives risks of alcohol consumption
increases risk of: -high BP -dementia -stroke -throat, bladder and stomach cancer -CNS disorders -vitamin and nutrient deficiencies (since alcohol are still calories, may make people eat less food which we need to get our nutrients in - alcohol may make us feel full but are empty calories so don't give us nutrients)
sex differences in alcohol metabolism
-females have less ADH in stomach cells, so females cannot metabolize as much alcohol in stomach as men can - men have more ADH and ALDH in stomach cells so can metabolize more of the alcohol in the stomach before it hits the bloodstream -females have less body water to dilute the alcohol --- so more of the alcohol hits the bloodstream in females (so liver has to do more of the alcohol metabolism in females) -fluctuations in female hormones can also affect alcohol metabolism -overall in females more of the alcohol ingested hits and stays in the bloodstream -females develop alcohol-related ailments more rapidly than men (since more less of the alcohol is metabolized in stomach of females, rely more on liver to metabolize it leading to more adverse effects)
causes of hangovers
Two theories:
alcohol is a diuretic so causes us to lose water -> brain cells can shrink as you lose water while drinking -- as brain cells start to swell back up as we rehydrate, feel nerve pain that causes pain during hangovers (BUT we do not have pain receptors in brain so this theory doesn't seem as likely)
Formaldehyde is converted to methanol in body; body prioritizes ethanol metabolism over methanol metabolism - when we drink, get ethanol production (from alcohol metabolism), but also have methanol production (from normal formaldehyde metabolism) -> body prioritizes ethanol breakdown/metabolism over methanol causing formaldehyde to buildup -> causes hangover **the only thing that clears hangovers is time
body can only deal with certain amount of alcohol at a time - what happens to the rest that is waiting to be metabolized?
remaining alcohol just circulates around body until it can be metabolized
chronic drinkers vs casual drinkers
chronic drinkers have significantly less effects after given amount of alcohol compared to casual drinkers
alcohol abuse
-contributes to 5 of 10 leading causes of death -increases risk for arrhythmia, hypertension, stroke, osteoporosis, brain damage, cancers, nutritional deficiencies, fetal damage, impotence, obesity, sleep disturbances, hypoglycemia, infections
Cirrhosis
-fatty infiltration of liver -in alcoholics, liver is pre-occupied with dealing with alcohol metabolism, so we start to get fatty deposits in liver -> scar tissue -> liver cells cannot do job -increased synthesis of fat -enlarged fat cells cut off nutrient and O2 supply to liver cells -engorged fat cells burst and die -if at early enough stage, can be reversible with lifestyle changes, but advanced stages are not reversible -leads to destruction of vital tissues -50% chance of death within 4 years
guidance regarding alcohol intake
-women: no more than 2 drinks per day or 10 per week (and no more than 3 in single occasion -men: no more than 3 per day or 15 per week (and no more than 4 in single occasion) -overall theme: all drinking should be done in moderation
blackouts (alcohol)
-interferes with transfer of knowledge from short to long-term memory -caused by disruption in activity of hippocampus -related to rate of alcohol ingestion (drinking quickly and especially on empty stomach make us more likely to blackout)
When do people usually start drinking (age)? what proportion of alcohol consumption is done by people who are underage?
-start drinking at average age of 14 years old -20% of alcohol consumers are underage
alcohol dependence
-most common psychiatric disorder -leads to loss of productivity, premature deaths, direct treatment expenses, legal fees, medical expenses -addictive and dangerous -has genetic influence (e.g. variation in ALDH and ADH affects alcohol tolerance; more likely to be alcoholic if parents are)
nutrient deficiencies of alcoholics
-alcoholics tend to be deficient in vitamin B12, folate, niacin, thiamin, vitamin A, vitamin C and vitamin D -thiamin deficiency impairs brain's utilization of glucose (leading to slower thought processing and memory impairments) -niacin used in alcohol metabolism -Korsakoff's syndrome (permanent damage to short-term memory) -withdrawal symptoms may be due to nutritional deficiencies (especially thiamin deficiency)
depression and alcoholism
-more symptoms of depression -> heavier drinking -use alcohol to self-medicate (initially alcohol may increase serotonin and dopamine, but alcohol is a depressant so eventually cause neural activity to be depressed)
symptoms/characteristics of alcohol dependence
-physiological dependence on alcohol -tolerance to effects of alcohol -alcohol-associated illness -continued drinking even in defiance of medical or social contraindications -depression and blackouts -facial reddening/flushing
CAGE screening
-helps diagnose/steer people to signs of alcohol dependence -C: have you ever feel like you need to CUT down on drinking -A: have people ANNOYED you by criticizing your drinking -G: have you ever felt bad/GUILTY about drinking -E: EYE-opener (have you ever had to drink in morning to get rid of hangover or steady nerves)
binge drinking
-4-5+ drinks in 2 hours -acute alcohol intoxication -leads to car accidents, unsafe sex, death, assaults, injuries, suicide, academic problems, etc. -can cause lifelong problems -practiced by almost half of college students
Twiggy (person)
lived on lettuce, water, and single serving of steak per day - was considered to be model of self-control
eating disorder
-psychiatric condition involving extreme body dissatisfaction and long-term eating patterns harming the body -family environment, unrealistic media images, sociocultural values, personality traits, gnenetic/biological factors, PTSD have all been found to contribute to development of eating disorders (no single cause of eating disorders - eating disorders can be caused by MANY factors)
disordered eating
-variety of abnormal or atypical eating behaviours used to reduce weight -unhealthful behaviours include binge-eating disorders, chronic overeating and chronic dieting
influence of family on eating disorders
-our family influences our eating patterns and what we eat -people who develop anorexia tend to have more rigid family structure -people who develop bulimia tend to to have less stable family organization -eating disorders occur more frequently in families with history of OCD, anxiety, and depression
influence of media images on eating disorders
photoshopped images of "perfect" body cause issues with adolescents being able to discern between reality and media fantasy - adolescents may develop a negative body image comparing themselves to these fake images may cause them to develop negative self-image
influence of media images on eating disorders
Western cult values slenderness as beautiful and as a sign of wealth, self-discipline - these cultural values influence person's body image and can contribute to eating disorders
influence of personality traits on eating disorders
-people with eating disorders may possess certain personality traits -may either be cause of eating disorders or may develop these personality traits as result of eating disorders -traits associated with anorexia separate than those causing bulimia
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