Aspects of Obesity Flashcards
how does the body use up energy?
basal metabolism (60-75%) thermogenesis (including digestion) = 10% physical activity = 15-30%
what gene is associated with obesity and why?
FTO gene
may cause people to eat more
what may be a link between obesity and cancer?
high insulin and oestrogen levels
name 4 obesity co-morbidities that are only associated with increased fat mass?
OA
back pain
Asthma
Sleep apnoea
how does obesity progress to hyperglycaemia?
obesity leads to insulin resistance
causes compensatory hyperinsulinaemia
eventually pancreas cant keep up and patient becomes hyperglycaemic and develops diabetes
what does adipose tissue secrete?
leptin adiponectin CRP TNF alpha IL-6 PAI-1 Oestrogen Cortisol free fatty acids many more
what is leptin?
hormone produced by adipose tissue
tells body how fat you are or how thin you are
what are the effects of a leptin deficiency or lack of leptin receptors in brain?
brain thinks that you are starving so increases hunger and food intake and decreases thermogenesis to reduce burning of fat
what are the effects of too much leptin?
doesn’t have the opposite effect to low leptin
once you get up to a certain amount of leptin it levels out so appetite is not decreased
how are adipocytes and macrophages related?
share a lot of overlapping functions
both can secrete cytokines (IL-6, TNF alpha etc)
both can store fat
become more alike in obesity as adipocytes secrete cytokines and macrophages store fat forming foam cells leading to atherosclerotic plaques
what can trigger inflammation in obesity?
adipocytes secrete cytokines attracting macrophages which then infiltrate adipose tissue
cellular stress can trigger - if the ER in adipocytes cant cope with metabolic demands of expanding fat mass then it activates pathways involved in inflammation and insulin resistance
these metabolic changes in the acute phase are also proatherogenc
what are the steps in the formation of an atherosclerotic plaque?…
1 = endothelial dysfunction
- chronic endothelial injury leads to endothelial dysfunction. LDL migrates into the intima. This attracts macrophages and lymphocytes which then migrate into the intima
2. Fatty streak formation - monocytes eat LDL and form foam cells, creating a fatty streak in the vessel wall
3. Smooth muscle cells migrate over the surface of the plaque forming a cap (thick = stable, thin = unstable)
how is very low calorie diets used?
only short term (6-8 weeks)
not sustainable as only amounts to around a glass of milk per day
options for hypocaloric diets?
portion control/calorie counting low carbs low fat very low calorie diet (VLCD) meal replacement (e.g slim fast)
how does orlistat work?
blocks lipase so inhibits absorption of dietary fat
loose up to 1/3rd of ingested fat in faeces
what are the 3 most common bariatric surgeries in the UK?
gastric band = restrictive
gastric bypass = restrictive and malabsorptive
sleeve gastrectomy = restrictive
common problem with gastric band?
band slipping
which is the most effective approach to weight loss?
gastric bypass as both restrictive and malabsorptive
all surgical approaches are more effective than medications and lifestyle
what is basal metabolic rate?
amount of energy expended at rest
= minimum energy consumption
what contributes to resting metabolic rate?
fat mass and fat free mass
how does resting metabolic rate change with weight?
higher in obesity
lower in weight loss
what is adaptive thermogenesis?
the large fall in resting metabolic rate seen in weight loss which exceeds predicted fall
what are the implications of adaptive thermogenesis?
means weight loss will level off even if youre still doing the same things
