obesity Flashcards
what is obesity?
BMI > 30
a condition of abnormal or excessive fat accumulation in adipose tissue, to the extent that health is impaired
what are possible problems with BMI?
muscular people have high BMIs
it is based of western white people
a high BMI doesnt necessarily mean you are unhealthy
it was designed to be used at a population level, or when you have minimal information about a patient, as an estimate
it isnt life or death
what drives obesity?
people dont want to be obese, so why are they? (eg. people say theyd rather walk away from their marriage etc)
is is decently genetic, identical twins (even those who grew up in different environments) show similar chances of being obese
it is also environmental
what is the genetic basis of obesity?
MANY gene loci give a predisposition for various aspects of obesity (eg. BMI, visceral adiposity, waist:hip ratio)
eg. MC4R (melanocortin 4 receptor)
is a big one
and the presence of Lectin in the body
these genes effect many things such as appetite
and reward centres.
how is the prevalence of obesity changing?
it is increasing with every decade
america is really bad, but UK isnt great either
getting worse in south asia too
in communities that are becoming urbanised
what environmental factors may drive obesity?
access to public parks car usage screen time education level education achievement poverty social deprivation
how, specifically in terms of risk, do genes associated with obesity effect it?
in a healthy environment, people who are genetically resistant are minutely less likely to become obese than those who are genetically prone
in a toxic environment, those who are genetically resistant are a tiny bit more likely to be obese than in a healthy environment
those who are genetically prone are WAY more likely to be obese
roughly how many people are obese worldwide?
(2016)
> 1.9 billion adults were overweight
of these >650 million were obese
it is a big problem
what are the comorbidities associated with obesity?
depression stroke sleep apnoea myocardial infarction hypertension type 2 diabetes mellitus bowel cancer osteoarthritis peripheral vascular disease gout
how is BMI associated with mortality?
people with a normal BMI have the lowest mortality ratio (1.0)
BMI > 25 mortality is ~ 1.25
> 30 ~1.5
> 35 ~2.0
and it keeps increasing
(also people with low bmi (<18.5) have a slightly increased mortality)
how do we assess and manage obesity?
determine degree of overweight/obesity –>
assess lifestyle, comorbidities and willingness to change –>
management: lifestyle changes, drug treatment
if worse
consider referral to specialist care –>
specialist assessment and management: surgery and follow up
how do we treat obesity?
depending on extent:
lifestyle advice diet (balanced, fruit+veg) physical activity drugs surgery
what drugs are used to treat obesity?
orlistat
maybe some more specialised drugs used in diabetes
what is orlistat?
Derivative of an endogenous lipstatin
produced by Streptomyces toxytricini.
Gastric and pancreatic lipase inhibitor
Reduces dietary fat absorption by around 30%.
but not actually that effective in weight loss, although it doesnt do much harm
what are the side effects of orlistat?
attrition rates are high, around 33%
people dont like being on it much
steatorrhoea faecal urgency oily spotting faecal incontinence possible deficiencies of fat soluble vitamins (ADEK)
what is bariatric surgery?
considered in patients with BMI:
>30 and newly diagnosed T2DM
>35 and other comorbidities
>40
when non surgical measures havent worked significantly for at least 6 months
when receiving specialist management
if they are generally fit for anaesthesia and surgery
are committed to the need of long term follow up
what are the 3 main types of bariatric surgery?
Gastric bypass:
the top part of your stomach is joined to the small intestine, so you feel fullersooner and do not absorb as many calories from food
gastric band:
a band is placed around your stomach, so you do not need to eat as much to feel full
sleeve gastrectomy:
some of your stomach is removed,soyou cannot eat as much as you could before and you’ll feelfull sooner.
which method of bariatric surgery is most useful?
gastric bypass gives the highest weight loss
then sleeve gastrectomy
then banding
(they are all much more effective in giving weight loss than drugs)
