lec 4 Flashcards
obesity occurs as a result of
-positive net energy balance (intake over expenditure)
-what factors predispose to positive energy banlace? (eating and not exercising, stress eating etc)
what do prevention strategies aim to do
to prevent positive energy balance
-all treatments for obestiy aim to induce negative energy balance
Obesity pathogeneisis invlolves…
physiological defense of higher level of body fat
What are the behavioural interventions for the preventiona dn or treatment of tpye 2 diabetes and obesity
1) Primary prevention
-occurs between health and lean individuals and prediabeteic/overweight
(improve insulin sensitivity and prevent pos energy balance and weight gain)
2) Secondary prevention
-occurs between pre diabeteic and overwieght, and diabetic and obese
(early detection and reversal/prevention of disease, prevent pos energy balance or induce negative energy balance and improve insulin sensitivity)
3) Tertiary Prevention
-between diabetic and obese and CVD and death individuals
-prevent/delay complications (prevent +ve energy balance or induce neg balance and improve insulin sensitivity)
Possible strategies to reverse the obesity epidemic
Control: no prevention or treatment provided
-results in incline of weightgain (natural progression of it)
Strategy one: prevent positive net balance
-stops gradual weight gain of the population
Strategy 2: Treatement of obesity of those who already have it
-induces negativge energy balance rto produce weight loss , this achieve energy balance at levels lower than normal
is diet induced weight loss effective in obese indivudals
no, short term weight loss can be achieve thorugh dietary restrictions, but only a small minority of people maintained this weight loss long term
what does obesity pathogenesis also involve
-the physiologucal defense of a higher level of body fat (weight)
ie hormonal adapatations occur to increase hunger and drive to eat to encourage weight re-gain after weight loss
-subjects had a 3 month high protein low fat diet, and they lost 17% weigjt loss
-followed a diet for three months after to maintain stable body weight
results: before weight loss, ghrelin levels were alot lower (before eating a meal cuz ghrelin induces hunger, so we have high ghrelin before we eat and low ghrelin after we eat) so the peak ghrelin amount was overall lower in those before the diet induced weightloss in comparison to those after the diet
-shows how hormone levels change and long term persistance of these pos hormones are present to induce weight gain after diet induced weight loss
Fasting and PostPrandial levels (after eating) of peripheral hormones at baseline
Ghrelin: week 10 diet has the hghest overall ghrelin levels, with week 62 being second and baseline being lowest
PPY: baseline is the highest with the 10 week diet bieng middle and 62 lowest
Amylin:baseline the highest, with 62 the middle
CCK: baseline the highest with 62 close with 10
Hunger vs desire to eat results at baseline, 10 weeks on a diet and 62 weeks
Hunger: baseline was the lowest after eating with 10 weeis ad 62 weeks being close
Desire to eat:
baseline was the lowest again after eating, , same results as hunger, 62 weeks had greater hunger and desire to eat after 240 minutes
What is the energy gap for weight loss maintenance
-difference between energy requirements before and after weight loss
-energy requirements before weightloss are typically higher than after weightloss of 40 pounds is (-300 to 500 kcal less)
-RMR (resting metabolic rate) decreases with body mass
-TEF (Thermic effect of feeding) decreases with total energy intake (less food means less energy needed to digest and stuff)
-Cost of physical activity decresases with weight loss (as it is releated to body mass)
Why does the cost of physical activity decline with weight loss?
-cost of physical activity is the amount of energy needed to perform physical activity adn this is dependent on body mass because if there is more mass to move, then the amount of energy needed is more so when we lose weight our cost of physical acrtibity decreases ( we burn more for ther same physical exercise done when we are heavier than when we are smaller because it takes more energy to move)
so what is the energy gap for someone who lost 80 pounds
600-100 kcal decrease
-energy gap is 300 to 500 kcal for40 pounds lost
-rememebr energy gap is the energy different between before weight loss and after weight loss
What is the phenomenom called metabolic adaptation
-IDEA THAT WEIGHT LOSS RESULTS IN DECREASES IN RESTING METABOLIC RATE AND OFTEN ENERGY COST OF PHYSICAL ACTIVITY THAT IS BEYOND WHAT IS EXPECTED due to changes in body weight composition
-long term persistance of adaptice thermogenesis (body slows down its met acitivty rate as a way to conserve body weight) associated with reduced t3 and t4 (thyroid hormones that control met rate, high levels means more calories burnt), decreased sns and reduced cost of physical activity
why are there decreases in resting metabolic rate during weight loss
this is due to the decrease in thyroid hormones such as t3 and t4, they are what stimulate metabolic rate, more there is, the higher calories we burn
-adaptive thermogenesis is also turned on which is the bodies way of conserving energy by slowing met rate
-decreased sns activity means less activation of things that burn calories too so less is burnt at rest
-takes less calories to exercise
what is the persistent metabolic adaptation found during weight loss bigest loser cmpetition
basically, it was found that years after the weight loss, these individuals were burning LESS than what was expected of their new weight. THis is because during weight loss, their bodies ADAPTED (adaptive thermogenesis) to being more metabollically efficient, meaning that less calories are burnt, so this means that even at this reduced weight, they are able to be metabillically efficient (which is bad because it means that it is easier for them to gain weight again ebcaseu they are burning less calories than someone of the same weight class)
this is the metabolic adapation phenomemon
most pf these people gained some of the weight back after 6 years
fat free mass was relatively the dsame but fat mass change and body weight changes increased
for the biggest loser competition individuals , what were the RMR and MEt adaptation results
RMR after 6 years was relatively the same as the amount at 30 weeks, this is weird because if they gained back the weight( which alot of them did , atleast soe of the weighht) they should be haing a higher RMR but they are not
WEIRD because RMR is in corelation with body mass, so if it is increased bondy mass, rmr should be higher but in this case they gained the weight back, so they have increased body mass but their RMR is still the same as when they lost weightt
this shows that their bodies are still in a METABOLIC CONSERVATION MODE which should not be the case because they are now having extra calroies to spare (they are not in negative energy balance)
so metabolic adaptation aslo did not decrease much which is weird because that means that their bodies ar still buring fewer calories than expected even though their weighr is higher.
Your weight loss and maintence of weight loss
SO how do we adress the energy gap and keep the weight off
so if our energy requirements after weight loss as less, but if we regain the weight it is still less, and we have metabolic adaptation where our bodies are too metabollically efficient for the weight class that we are in, how is it possible to keep the weight off if AFTER WEIGHT LOSS OUR ENERGY REQUIREMENT IS LESS THAN EXPECTED (Ie we would have to be soooo strict to keep it off because our bodies adapted too well)
what is the NWCR and how to be eligibke
-national weight control registry
-individuals can give info to studu this
1) Individuals who have maintained a weight loss of atleast 30 pounds can eter the NWCR (national weight control registry)
2) participants provide info by completing questionairs about weight loss and weight maintainence
3) currently following over 10,000 individuals who on average are maintaing a weight loss of approx 70 lllbs for a period of 6 years
4) few similarities of how nwcr participants report losing weight, although almost 90% report that they lost the weight through diet restirction and physical acitivity bUT each individual did it different
So what were the secret strategeies that the NWCR participants used to maintain their weightloss
1)low calorie low fat diet
-24% total energy from fat
-consistent with studies that saw low fat better than high fat
2)consistnet monitorying of body weight, food intake, and physical activity
3)eating breakfast everyday
4)very high levels of physical activity
-2800 kcal/wk of physical activity (60 mins per day of moderate intense physical activity
threshold of energy expenditure and balances
-it is hypothesized that the body weight regulatory mechanisms that our body has are there to match intake and expenditure
-at low levels of energy expenditure, it becomes difficult for our body to match expenditure to the intake so then we gain weight
-increasing energy expenditure above threshold is necessary to have body weight stability which is why physical activity is important
so as long as we are above the threshold energy expenditure, we will not have weight gain because our body can use its built in regulatory things
so did the decline of physocal activity lead to weight gain
yes sprt of, this decline and increase in food intake
A hypothetical expression of several factors related to energy balance and weight maintenenance
Diagonal line: energy balance where energy in equals out
middle box: represents energy balance and weight stability along a wide range of energy balance levels
- in the middle of the box means that we are very well balanced
-basically this is the hypothesis that the built in regulatory mechanisms of the body
-at low levels, it is difficult for the body to match energy intake with energy expenditure
triangle bottom corner: indicates how weight gain is more likely at low levels of energy balance (energy intake and energy exp not equal, making a pos balance)
-there is a normal distributio of sceptibility to dysregulation that causes the weight gain ie each person may have it at a different point
triangle top corner:
-people losing weight but having too much expenditure and not enough kcal
what is the american college of sports medicine position stand for approriate physical acitivity for weight loss and prevention of weight regain for adults
PA to prevent weight gain: 150-200 min per week
PA for weight loss: PA less tha 150 min per week is minimal weigt loss, greater is modest weight loss, 225-420 min per week is 5-7kg weight loss
PA for weight maintenance after weight loss: -200 to 300 min wk
possible strategies to reverse the obesity epidemic
primary treatment: rememenr this one is to prevent weight gain so the treatement here is 150-250 min/week
seconary treatment:, achieve energy ba;ance at a higher weight, treat those with obesity by lowering energy balance, lowering weight
-225-420 min/wk
Prevetion of weight regain 200-300 min per week
