Physiology of appetite and weight Flashcards
Food intake should = what?
Energy expenditure
What is the average amount of calories needed per day?
Women - 2000
Men - 2500
How many calories per gram are in carbs, fat and proteins?
What are the parameters for BMI?
What is a more accurate parameter for healthily weight in asians?
Waist circumference
What are the hunger hormones in the stomach called?
Ghrelin
What is the name of the axis in the GI tract that generates neuronal and hormonal signals of hunger?
Gut-brain axis
What are the satiety hormones?
Peptide YY in gut
Cholecystokinin
Leptin in fat tissues
Where is the feeding centre in the brain?
In the lateral nuclei of the hypothalamus
Where is the satiety centre in the brain?
Ventromedial nuclei of the hypothalamus
Lesions in which parts of the hypothalamus can affect appetite and feeding?
Paraventricular nuclei
Dorsomedial nuclei
Arcuate nuclei
What does anorexigenic mean?
Something that causes a loss of appetite
What does orexigenic mean?
Something that causes an increase in appetite
Which molecules can decrease feeding (anorexigenic)?
Which molecules can increase feeding (orexigenic)?
How does Ghrelin affect appetite?
Ghrelin interacts with AGRP neurons –> produce agouti related protein and neuropeptide Y.
AGRP stimulation increases food intake.
How is POMC involved in appetite?
Insulin/Leptin/CCK interact with POMC neurons. POMC produces a-MSH (Melanocyte stimulating hormone) and cocaine and amphetamine-regulating transcript (CART).
POMC stimulation decreases food intake.
How does a-MSH affect appetite regulation?
a-MSH (Melanocyte stimulating hormone) stimulates neuronal melanocortin receptors (MCR-3 and MCR-4) which then increases energy expenditure.
How does AGRP affect appetite regulation?
AGPR is an antagonist to MCR-4. MCR-4 is stimulated by a-MSH and increases energy expenditure.
AGRP prevents this increase in energy expenditure.
Which hormones can block AGPR?
Insulin
Leptin
CCK
Which neuronal mutations have been linked to obesity in children?
POMC
MCR-4
What affects satiety?
Meal quality
Meal quantity
Nutritional status
Energy balance
Where is leptin produced and expressed?
Produced in adipose cells
Expressed in white adipose tissue
What is the function of leptin?
Regulates energy homeostasis - provides energy storage signal to hypothalamus.
Neuroendocrine functions, metabolism and immune functions
A deficiency of leptin in mice led to what?
obesity
Does increased amounts of adipose tissue produce more of less leptin?
More
What effect does leptin receptor stimulation have on fat?
It decreases fat storage.
Which factors override the effect of increased adipose leptin in the regulation of food intake?
Society and culture
Above which BMI is someone considered morbidly obese?
> 40
Which genetic syndromes are associated with obesity?
Prader-Willi
Bardet-Biedl
Which neuroendocrine disorders can cause obesity?
Hypothalamic lesions
Cushing’s syndrome
Hypothyroidism
How much weight should those with obesity aim to lose?
10%
0.5-1kg per week
What is the MOA of lipase inhibitors?
Inhibits lipases in the lumen of the gut.
It prevents the hydrolysis of dietary fat inso absorbable FFAs/glycerol.
What are the adverse effects of lipase inhibitors?
Flatulence, oily faecal leakage, diarrhoea.
Reduction in the absorption of fat soluble vitamins - ADEK
Which drug is a lipase inhibitor?
Orlistat
What is the MOA of GLP-1 agonists?
Stimulates POMC to reduce hunger, energy intake and food cravings.
Inhibits AGRP to increase satiety.
What are the side effects of GLP-1 agonists?
Pancreatitis
What is an example of GLP-1 agonists?
Liraglutide
Semaglutide
What are the pharmacological treatments for obesity?
Lipase inhibitors
GLP-1 agonists
What are the different tiers of weight management?
Tier 1 - Universal services
Tier 2 - Lifestyle management
Tier 3 - Specialist management. Assessment for surgery, medications.
Tier 4 - Pre-op assessment
What are the advantages to bariatric surgery?
25-20% weight loss
Life-long treatment cost savings
Improve co-morbidities
