Obesity Flashcards
what is BMI?
- developed by who? year?
- was known as what?
- metric formula? vs imperial formula?
international measure of obesity –> body mass index or body mass indicator –> ratio of weight to height
- developed by Belgium statistician Adolphe Quelet (1796-1874)
- was known as Quetelet index
- weight (kg)/height^2 (in meters)
- (weight in pounds * 703)/height in inches
what is the name of the index where you take height more into account (height^3)?
ponderal index
what are the cut-off values for underweight, normal range, overweight, obese 1, 2 and 3
UNDERWEIGHT: <18.5
severe thinness: <16
moderate thinness: 16-16.99
mild thinness: 17-17.99
NORMAL: 18.5-24.99
OVERWEIGHT: 25-29.99
OBESE 1: 30-34.99
OBESE 2: 35-39.99
OBESE 3: >40
when does BMI not work?
doesn’t take into consideration body composition!
- is Herschel Walker –> football player: just does push ups, pull ups and skip rope –> 4% body fat, 33 BMI bc all muscle mass
do children also have BMI cut-offs?
no! follow a percentile chart! where x-axis is age, and y-axis (2 different scales on right vs left) is BMI!
- check your percentile!
- different charts for boys vs girls
what are the generally accepted classifications for BMI and weight status in children and adolescents?
UNDERWEIGHT: BMI less than 5th percentile for age and sex
HEALTHY WEIGHT: BMI btw 5th and 85th percentiles
OVERWEIGHT: btw 85th and 95th percentile
OBESE: greater than 95th percentile for age and sex
what is the relationship btw obesity and mortality?
- men vs women
U or J shaped relationship! NOT a linear relationship!
- unhealthy to be at low BMI and too high BMI –> sweet spot in the middle –> where healthy BMI cut-offs are made!
- men = more J
- women = more U ish
how is obesity defined by adiposity? males vs females
can you have 0% fat?
- males: 25% body fat or greater
- females: 30% body fat or greater
you CANNOT! - fat in brain, organ lining, cell membrane
overweight vs obese definitions
OVERWEIGHT
- indicates too much body weight for a given height and frame
OBESITY:
- refers to an overfat level that brings with it increased risks of serious and fatal diseases
*can be overweight without being obese
what does epidemiologic measures measure? of which 3 events
measures FREQUENCY at which an event occurs!
- injury
- disease
- cause of death
what is an incident case?
- ie what can you look at?
new occurrences of these events during a time period of interest (ie pandemic)
- health status changes during time of interest! deaths from a certain disease, not injured to injured…
trends in obesity prevalence among adults in canada from 2005 to 2017?
- generally
- stratified by age
- by province
- gradual increase (from 21% to 27% ish)
- younger adults (18-29) are less likely to be obese than older/middle aged (30-79 yo)
- more prevalent in territories, saskatchewan, newfoundland and labrador, NB –> then manitoba, NS > ontario, qc, alberta > BC
define “rate” in epidemiology
(number of cases, events or deaths)/population of interest
ie medically attend injuries in school for population of interest
- across some period of time
in 2022, how many people & percentage in canada were overweight vs obese?
OVERWEIGHT: 10M –> 35%
OBESE: 8.7M –> 30%
obesity trends among US adults
- from 1985 to 2023
1985: half of states that had data were <10%
- over the years, more states surveyed + more dark blue (10-14%)
- 1989: half of states in 10-14%
- 1991: new color: 15-19%
- 1994: no 10% anymore
- 1996: more than half 15-19%
- 1997: new colour: >20%
- 1999: half of country >20%
- 2001: new colour: >25%
- 2005: only colorado and massachussets in 15-19 –> all others are bigger –> new colours: >30%
- 2011: change colour code au complet –> smaller category is <20%, biggest is >35%
- 2019: add categories of 35-40, 40-45, 45-50, 50+
- 2023: most states 30-40% ish, some states 40-45%
increased obesity in US –> similar to which other disease’ trend in US?
diabetes!
does self-reported or measured BMI report higher BMIs?
measured!
*self-reported limitations:
- mostly underreported
- ppl might not weigh themselves, especially as they get heavier, genuinely don’t know their height and weight
- men tend to overreport height
- women tend to underreport weight
which age groups have the most increased BMI from 1978 to 2004 in canada? why is it worrisome?
- 12-17 –> more than double
fat kid will lead to fat adult - 25-34 –> more than double
- 75+ –> more than double
what is sarcopenic obesity?
when you have all the metabolic problems of being obese/increased fat but you also decrease in muscle so become frail
are women or men more likely to be underweight, normal weight, overweight, obese 1, obese 2 and obese 3 in canada?
underweight: women ish more likely
normal weight: women > men
overweight: men > women
obese 1 and 2: similar, no difference
obese 3: women > men
are obesity rates increasing in all countries?
no! not in Japan and Sweden
- vs increasing in Australia, Brazil, England
what are the trends of obesity rates from 18 yo to 75+ yo in Canada?
- 18-24 = least
- increasing over middle years/45-65 (peak) –> then decrease (partly bc obese people don’t live that long
what might account for differences in COVID mortality from Italy and China?
increased prevalence of obesity in older adults in Italy compared to China
+ pandemic: eating for comfort, decreased PA, less pressure, ppl didnt see them
how much are the economic costs due to physical inactivity and excess weight?
- trend?
P inactivity: 200B ish
excess weight: 200B ish but a bit higher than physical inactivity
- combined: around 460B –> increasing to about 650B $ in US
- how to we define optimal body weight?
- how to we determine optimal body weight?
- what are problems associated with concept of optimal weight?
- different depending on goal ish –> weight optimal for health, for appearance, for peak performance!
- ie marathon runner –> take height and weights of all elite olympic finalists
- eating disorders, sports with weight classes
what are the 3 compartments of body composition?
- muscle mass
- skeletal mass
- fat mass
+remainder (connective tissue)
what are the typical body composition changes from 25 to 55 yo?
- body weight increases by 30lbs (gain 1 lb per year)
- fat mass increases by 45 lbs (gain 1.5 lbs per year)
- muscle mass decreases by 15lbs (lose 0.5 lb per year)
what are the 2 main categories of body composition ish? + subcomponents
LEAN TISSUE = metabolically active tissue (LBM)
- muscle
- bone
- connective tissue
- organs
FAT TISSUE
- subcutaneous fat
- internal fat (android obesity)
is a hard beer belly good for health? vs jiggly fat?
HARD beer belly = visceral fat
- the worst for health
VS jiggly fat = subcutaneous = less bad
what are lab methods (9) vs field methods (3) for measuring body composition?
LAB
- underwater weighing (use archimede’s principle: measure weight underwater, calculate density, estimate body fat)
- bioelectric impedance (prof doesn’t believe it’s good, fat blocks current more than water, muscle…)
- ultrasound (wand)
- x-rays
- MRI (more precise, but very expansive)
- CT
- DEXA
- body pod (for children, no radiation, air displacement)
FIELD
- body mass index
- skinfold measurements
- circumference measurements (ie height to wt ratio)
apple vs pear
- which is better?
apple = central fat = storing weight higher = greater risk for metabolic risk
VS pear = store fat below waist –> allows women to handle pregnancy better
most field methods (+ what?) for assessing body comp have margin of error of how much?
+/- 4%!
also bioelectric impedance
waist/hip ratio
- related to (2)
- how to calculate?
- American Heart association standards for males vs females?
- related to android obesity (central) and internal body fat
- wait circumference/hip circumference
- males: <1.0
- females: < 0.8
compare android vs gynoid obesity
- what?, metabolic consequences?
- also visceral vs subcutaneous fat –> hard or jiggly?
ANDROID: mostly fat in upper body –> more health consequences
- apple
GYNOID: mostly fat in lower body: might be obese but less metabolic consequences
VISCERAL: hard fat = bad
SUBCUTANEOUS: jiggly, less bad