L11 - Appetite and weight Flashcards
How to measure obesity?
BMI Waist circumference skin-fold thickness ethnicity specific cut offs bioelectrical impedance analysis
Medical consequences of obesity
metabolic syndrome/T2D cardiovascular disease respiratory disease liver disease cancer reproductive dysfunction joint problems more likely to have co morbidities
metabolic syndrome
visceral obesity - central dyslipidemia hyperglycemia hypertension Insulin resistance is the underlying patho mechanism BMI more than 30
Patho of metabolic syndrome and insulin resistance
inc free fatty acids lipolysis of visceral fat gluconeogenesis dyslipidemia proinflammatory cytokines TNFa and IL6 lead to increase insulin resistance reduced expression of glut4 reduced tyrosine kinase activity of insulin receptor
Respiratory problems
obstructive sleep apnoea
hypoxia
pulmonary hypertension - right heart failure
effects on GI / Liver
non-alcoholic fatty liver non-alcoholic steatohepatitis may progress to cirrhosis, portal hypertension, hepatocellular cancer gallstones reflux
cancer and obesity
breast, endometrial, oesphagus, colon, gall bladder, renal, thyroid
mechanisms include increased insulin, increased oestrogen, increased free IGF1
reproductive system and obesity
Polycystic ovarian syndrome
male hypogonadism
adverse pregnancy outcomes
Joint problems and obesity
osteoarthiritis
gout
Psychological problems and obesity
eating disorders
depression
Genetic causes
Rare; prader-willi syndrome
Bardet-Biedl
Common - polgenic
susceptibility genes
other causes: hypothyroidism
cushings syndrome
Environmental causes of obesity
diet - high fat/sugar socioeconomic factors physical activity car ownership tv viewing
Fetal programming and obesity
Programming’: stimuli / insults at critical periods have persistent biological effects
Mechanism: epigenetic modification of gene expression
Gut microbiome and obesity
Differences in gut bacteria
Can be induced by diet e.g. high fat diet
Transplantation of faecal material alters insulin sensitivity
Regulating appetite and weight
slow acting hormones that regulate body weight are
LEPTIN
INSULIN
signals % body fat to the hypothalamus to reduce food intake or increase energy expenditure
Rapid acting peptides that regulate meal sizes
Ghrelin encourages eating whilst CCK reduces eating
PYY reduces eating
they are released from GI tract
THESE SIGNAL BACK TO HYPOTHALAMUS WHERE THERE ARE ACCELERATOR NEURONS (NPY/AgRP neurons) WHICH STIMULATE EATING
BRAKE NEURONS - POMC NEURONS INHIBIT EATING