obesity Flashcards
what are risk factors for the development of obesity
excess body fat caused by chronic positive energy balance from either high energy intake or low energy expenditure.
assessed by BMI
increased risk in 1st world countries due to reduced activity
what are co-morbidities associated with obesity
major risk factor for coronary heart disease (coronary arteries become narrowed or blocked)
increased BP and Plasma cholesterol levels
increased risk for type 2 diabetes
which are additional risk factors for CHD ^
probable evidence that increased body fat increases risk for:
oesophagus
pancreas
liver
colorectal
breadt
endometrium
kidney
mouth
stomach
gall bladder
ovary
prostate cancer
what is the mechanism of action of orlistat
AKA tetrahydrolipostatin
inhibits gastric and pancreatic lipases irreversibly (covalent bonds formed with serine residues in active site of lipases)
prevents metabolism of fats leading to less fatty acids being absorbed from the GI tract
needs to be taken before each meal
side effects:
steatorrhea (decreasing fat intake solves this problem)
fecal incontinence
prevents uptake of energy from diet
what is the mechanism of action of liraglutide and semaglutide
GLP-1 receptor agonists.
has appetite supressive effects in the hypothalamus and increases secretion of neurotransmitters POMC and CART to stimulate anorexigenic neurones and inhibit orexigenic neurones leading to a decrease in appetite
Also supresses dopamine signalling from high fat foods by blocking reward pathways
SC injection
reduces appetite targets reward pathways
what is the mechanism of action of mysimba
combination of naltrexone and bupropion
bupropion is a dopamine and NA reuptake inhibitor. increases levels in brain leading to greater activation of receptors. less dopamine is needed to get a response from food. also activates appetite supressing neurones
naltrexone opioid antagonist prevents negative feedback pathways that would counteract bupropion action
reduces appetite and targets reward pathways
what is the mechanism of action of silbutramine
NA and 5HT reuptake inhibitor
5-HT acts at 5-HT2C to increase release of POMC and CART which decrease food intake. Also acts at 5-HT1B to decrease release of NPY and AgRP, which increase food intake.
no longer used due to increase in BP and HR
reduces appetite
what is the mechanism of action of lorcaserin
5HT2c receptor agonist.
5HT2c receptors activate POMC CART neurones
reduces appetite
what is the mechanism of action of tesofensine
triple reuptake inhibitor
increases HR and BP
less dopamine is needed to get a response from food
5ht controls balance of the release of appetite supressing (pomc and cart) and appetite stimulating (NPy agRP) neurotransmitters
alter expression of nT in hypothalamus 5-HT1b switches off NPy agRP neurones
5HT2c receptors activate POMC CART neurones
reduces appetite and targets reward pathways
what is the mechanism of action of rimonabant
CB1 receptor antagonist
decreased motivation to eat palatable food
anorexigenic effects in hypothalamus
stimulates satiating signals in GIT
lipogenesis inhibited
depression side effect
reduces appetite
what is the mechanism of action of qsymia
phenteramine and topiramate
phenteramine increases catecholamine levels in brain (na,a,dop)
increases HR BP
topiramate GABA agonist (unknown MOA)
targets reward pathway and reduces appetite
what are some dietetic treatments for obesity
Very low calorie diets:
done under medical supervision only for quick weightloss for bariatric surgery (usually 400-600 calories per day)
has all proteins vitamins and minerals
restrictive diets: around -500 calorie less than amount calculated to maintain body weight slow weight loss (max weekly weightloss of 0.5-1kg. energy balance needs to be negative (input-consumption))
