Flashcards in Weight management Deck (32):
What is energy balance?
positive energy balance = weight gain
negative energy balance = weight loss
What is the average weight gain of americans?
0.45-0.9kg/year over past decade
How many calories is a kg of weight gain?
7,700calories with excess energy stored at about 50% efficiency
decreasing energy intake by 100cal/day would stop this weight gain
How do we measure the body?
body size - volume, mass, length, surface area
body structure - arrangement of body parts
Why do we not want fat on an athlete?
in any spor where the body must be moved this is detrimental to performance.
adds body mass without capacity to generate force
increases the mass that must be moved
increases the amount of metabolically active tissue
What are the usual percentage body fats?
olympic marathon runners - 3-4%
tour de france cyclists - 4-6%
rugby - 12-15%
What are the usual body masses for female athletes?
female distance runners - 50-55kg
female shot putters - 75-85kg
ballet - 45kg
How do you calculate BMI?
what are the BMI ranges?
underweight - 18 and under
overweight - >25
obese - >30
What are the limitations of BMI?
Does not take into account body composition
Results in misclassification of some athletes and individuals
two individuals may have the same BMI but not same composition
Not good for children or elderly
Overall good for population assessment
What is hydrostatic weighing?
different tissues have different densities
based on the principal that fat is less dense than lean mass. It is considered the gold standard for measuring. has an error of 2-5%. problems include failure to exhale and GI gas etc
What is the skinfold measurement?
based on the principal that a relatively constant portion of fat is under the skin
relatively good method
should be done by the same person
What is the air diaplacement measurement?
displaces air based on body volume
body density can then be calculated by mass/volume
slight lower values than under water weighing
What is bioelectric impedance?
based on the principal that lean tissue conducts electricity better than fat
less resistance = higher water content
need to control hydration, position of electrodes, previous exercise
How is imaging used to measure body mass?
take images of body sections and calculate fat
very accurate 2-3% error
used to be prohibitively expensive but price is coming down
What is essential fat?
fat present in nerve tissue, bone marrow, organs and all membranes
cannot lose this fat without physiological consequences
3% of body mass in men. 12% of body mass in women
What is non essential fat?
storage of excess energy
What is the total body fat for men?
<5% not recommended
What is the total body fat for woman?
<12% not recommended
What is the weight loss registry?
a database of those who have maintained a weight loss of over 15kg for over a year
What is weight loss positively associated with?
decreased refined sugars and fat, snacks and sweets
increased intake of total CHO and fibre, low fat dairy foods, breads, cereals, fruits and veges
What should the diet composition of someone who is trying to lose weight be?
more CHO than Fat as CHO stores are limited but fat stores are not
Why can a decreased fat diet be effective?
because fat is energy dense and has 2x as much energy per gram than CHO/protein
high fat foods taste good and increase spontaneous intake of food
fat is efficiently stored and takes very little energy to do so
fat intake does not increase it's oxidation
What weight loss method should the clinically obese use?
very low energy diet.
done in a hospital setting
not conducive to activity
nausea, bad breath, hunger, light headedness, hypotension
What are food-combination diets?
certain foods cannot be combined
end up being calorically restricting and does not matter what combinations are
What is a high protein diet?
Thermic effect of protein and satiety.
Thermic effect calculates to minimal losses even over a year
What is a zone diet?
based on selective scientific evidence
hard to follow being calorically restricting
detrimental to exercise performance
What is the low CHO diet?
ketogenic diet to increase fat metabolism and appetite suppression
eliminates healthy fruit/fibre
promotes high fat intake
body starts to crave CHO
What has lead to the body weight set point?
decreased mass decreases RMR.
so smaller you get less weight you lose. bigger you get more weight. so weight does not vary that much
What is android obesity?
metabolically more active, fat stored in abdo
What is gynoid obesity?
fat stored in lower body, harder to metabolise