Obesity Flashcards
BMI is
Mass (kg) /height^2 (m)
Things to consider with BMI
South Asian, Chinese, Middle Eastern,black African or African Caribbean populations
Measures overall weight, not fat
No detail on weight distribution
BMI considered overweight
23-27-4
BMI considered obese
27.5 +
Health risks of obesity
CVD
Diabetes
Some cancers
Musculoskeletal diseases
Obesity : ,about 80-85% of developing?
Type 2 diabetes
Fundamental cause of weight gain is?
An energy imbalance between calories consumed and calories used up
Factors contributing to obesity?
Societal
Biological
Economic
Psychological
Complex factors regulating body weight
Body weight is very finely controlled
- homeostatic mechanism
Hypothalamic input
- people with injury to hypothalamus, more likely to put on weight
Neurohormonal integration
Lepton is the product of?
The ob gene
Where is Leptin synthesised?.
Adipocytes
- glucocorticoids, insulin and oestrogen increase
- B- adrenoceptor agonists reduce
What effect does leptin administration have on body weight?
Decreases it
CNS effect when hungry. Role of Leptin
Leptin decreases
Neuropeptide Y/ agouti- related protein neurons (NPY/AGRP) neurons are stimulated to release NPY or AGRP
CNS effect when feeding. Role of Leptin
Lepton levels increase
Stimulates prepro-opiomelanocortin (POMC) neurons in the brain which release another hormone= alpha- melanocyte stimulating hormone (alpha-MSH)
What is stimulated in the brain by hormones in response to hunger or feeding?
Neural pathways
Where are NPY/AGRP neurones and POMC situated?
Within the arcuate nucleus within the hypothalamus
Stimulation of POMC neurons by Leptin after feeding releases what hormones? Has what effects?
Release alpha MSH which act on various pathways to increase anorexic pathways
Lead to decrease in appetite and thus food intake, and increase energy expenditure
Stimulation of NPY/AGRP neurons by Leptin after hunger releases what hormones? Has what effects?
Releases NPY /AGRP which stimulate appetite
Increases food intake and decrease energy expenditure
Anorexia means
A decrease in appetite which is normal part of energy consumption and balance in the body, although used to describe a group of eating disorders characterised by low weight
Ghrelin is produced by?
Cells in the GI tract
Role of ghrelin when hungry
Levels are high, leptin =low
Inhibit its POMC neurons and stimulates the NPY/AGRP neurons to increase appetite and decrease energy expenditure
When do ghrelin levels fall?
After eating as lepton levels rise
Mutations in lepton pathways have been shown to underlie obesity.
List some Monogenetic causes of obesity linked to:
Leptin receptors
POMC neurons
Melanocortin receptors (MCR4) which are stimulated by (alpha- MSH)
Circulating levels of Leptin are normally (increased/decreased) in obesity?
Increased
Leptin in obesity happens how?
Via leptin resistance which is common in obesity, whereby it is produced but the body does not respond to it as effectively
Other factors in obesity
Inflammation: adipocytes produce cytokines, increased levels of TNF-alpha, IL-6
Oxidative stress: reactive oxygen species (ROS)
Polygenetic: about 50 genes strongly associated with risk (40 -70%), combination of environmental factors and genetic susceptibility
