Chapter 14- Weight Management Flashcards
what are three aspects of the physique which affect performance ?
body size
structure
composition
how is excess fat related to performance ?
excess fat is detrimental to performance and increases metabolic cost of activities, therefore lesser % body fat is advantageous
how much does genetics contribute to weight gain ?
25-40 % heritability
how many genes may influence weight ?
250
what aspect of weight do genes contribute to ?
the SUSCEPTIBILITY to weight gain (risk factors such as low RMR, high reliance on CHO metabolism, low lvl of spontaneous activity)
what kind of weight variation is found in a twin study of overfeeding ?
weight gain and loss has more variation between pairs of twins than within the pair
what was found in a Scandinavian study that examined the relationship between genes and physical activity when it comes to weight change ?
genes contribute to weight change, but in v active people genetic contribution decreases.
how does genetic contribution to BMI change with physical activity?
not much
how does genetic contribution to WC and %fat change with increased physical activity?
genetic contribution decreases
why do men lose weight easier ?
fat in men is more in upper body than in lower body. upper body is more metabolically active & susceptible for mobilization, while hip fat harder to recruit
also, fat storage is lower postprandially so for men less fat is stored
what kind of energy balance is required to lose weight ? how may one attain it ?
negative energy balance
by reducing intake or expenditure or both
what is appetite ?
integrated response to sight, smell, thought, tase of food that initiates or delays eating
what is hunger ?
a physiological response to a lack of food that initiates food-seeking behavior
what is satiety?
the feeling of fullness and satisfaction that occurs after a meal and inhibits eating until next meal
what is ghrelin concentration like before and after a meal
before: increases
after; drops to baseline
where in the brain is appetite regulated ?
arcuate nucleus of the hypothalamus
any physiological controls of hunger are overriden by what ?
memory, time of day, social situations
what are 4 main anorexigenic peptides ?
suppresses appetite
leptin
PYY
CCK
insulin
what is the main orexigenic peptide ?
ghrelin
what is the effect of exercise on appetite dependent on? (4)
intensity duration type ambient temperature (colder temp stimulates it more, like in swimming)
which intensity of exercise may suppress appetite ?
high intensity
what is the effect of exercise on weight management ?
short term, will give you a negative energy balance but in long run, dieting is important
which part of the body produces anorexigenic peptides ?
small intestine
what is RMR measured as post exercise ?
post exercise oxygen consumption (EPOC)
how can exercise change RMR ?
only small increase temporarily, but probably not a chronic change
how can weight loss negatively affect performance ?
lose weight means losing muscle mass and maybe muscle glycogen, risk of injury and fatigue
what matters more and is more effective: energy restriction or reduced fat intake ?
energy restriction, but should be done slowly and off season
why is reduced fat intake a realistic and practical way for weight loss ?
maintains glycogen stores and improves recovery (compared to energy restriction)
therefore better for athletes
what are very low energy diets used for ?
obese people rapid weight loss
how many kcal/d on VLED ?
400-800
is the VLED effective ?
yes
what kind of weight loss will you see in VLED ? what can be side effects concurrently ?
1st week: glycogen and water (fatigue)
after: fat mostly leading to ketosis
what kind of diet on VLED ?
liquid, mostly high protein, low CHO
how much CHO on VLED ? what are the implications for an athlete
<100g/day
so bad for athlete bc exercise capacity is impaired
with VLED, what can happen to BP
hypotension
what kind of consideration is advised w VLED ?
vitamin and mineral supplementation
why are low fat diets effective for weight loss ? (5)
fat energy is dense
high fat foods are palatable so tend to eat more
fat is less satiating than protein or CHO
fat is stored efficiently and requires little energy for digestion
fat intake doesn’t immediately increase fat oxidation
what is the effect of food combining diets ?
reducing energy intake by limiting consumption of for example protein and fat together
impairs performance and recovery
why do fad people recommend high protein diets ? (3)
say it promotes satiety and suppresses appetite
also has large thermic effect and less weight regain after energy restricted period ends
how effective is the high protein diet for athletes?
unknown bc most research done on normal ppl
what kind of food for the Zone Diet ?
40% CHO,
30% fat
30% protein
3 meals and 2 snacks a day
what is the logic behind the lower CHO in Zone Diet ?
less insulin response means more lipolysis
what blood profile is associated with the Zone Diet
better eicosanoid profile, improve oxygen and blood flow
why might the Zone Diet work ?
because of lower energy intake
3 caveats of Zone Diet:
hard to change eicosanoid profile
CHO intake has to be very small in order for insulin to prevent lipolysis
difficult food composition to maintain
what are two examples of low CHO diets ?
Atkins and Sugarbusters
what is the logic behind low CHO diets ?
low CHO means more fat oxidation
more ketones so more urine excreted
how do low CHO diets compare to a normal diet ?
not more effective
what is an effective energy density dietary strategy ?
eat food with same weight but lower energy content
which will be more filling: 200g fat or CHO?
both, it’s the weight that determines the amount consumed not the composition
can calcium and dairy reduce weight ?
no (research has found)
higher dairy intake (calcium 1000 mg) induced what ?
lower hypertension
what is a mechanism that may have suggested that calcium can help lose weight ?
calcium reduces calcitriol and therefore increases intracellular Ca+ and metabolism of adipocytes
which sweetener may cause GI problemes ?
sugar alcohols
do sweeteners help with weight management ?
no, quite the opposite may promote energy intake since the sweetness may trigger craving
which diets are the best ? (5)
1- DASH DIET (Dietary Approaches to Stop Hypertension, similar to food guide)
2- Therapeutic Lifestyle Changes
3- Mayo Clinic, Mediterranean, Weight Watchers
Therapeutic Lifestyle Changes diet- what is in it ?
high fiber, low fat
what is the Mayo Clinic diet ?
focus on lower energy density (fruit)
what is the Mediterranean diet ?
focus on whole grains, healthy fats, fruits
what is the Weight Watchers diet ?
portion control (low fat dairy, fruit, grains)
does increased fat oxidation aid weight loss ?
no
fat oxidation is active or inhibited at what intensities of exercise ?
active at low-med
inhibited at high
which exercise is more effective in preserving and increasing FFM
resistance
which exercise is more effective in body fat loss
resistance = endurance
which cardio will be more effective to burn fat ? walking or cycling ?
walking
what is the set point theory?
that body has a weight set point and body weight usually pretty constant
what is the minimal fat % for men and women
5% men
12% women
what is a realistic weight loss ?
1kg/2weeks
how many kcal deficit /lb fat to be lost ?
3500
what kind of meals are recommended for weight loss ?
5-6 smaller meals
what is a risk of dehydrating to make weight ? (more than 5)
decreased blood volume, increase core temp and HR
body protein is lost and decreased RMR
cognitive function, bone, performance bad
what are 2 recovery strategies to acute weight loss ?
fluids and electrolytes (with at least 50 mmol/L sodium) 1.5L/kg lost
carbs to regain muscle glycogen (use high GI)
what is a realistic weight gain ?
0.2-1 kg/week
lose weight during on or off season ?
off
