lecture 12 - Weight management obesity Flashcards
What is obesity?
accumulation of excess body fat
Why do genetic factors favour food storage?
because we store food for times when we are lean due to evolution when we didn’t always have food available.
Obesity … with age
increases
obesity is more common in the …. educated and …. societies
less educated and poor societies
Three are …. obese than undernourished people
more
How to assess obesity?
BMI - weight in KG / M^2
BMI ranges?
20-25 - normal
25-30 - overweight
30-40 - obese
40 + - severe obesity
What are some anatomical differences in the way we deposit fat?
Android (apple shape) - located in the central abdominal area
Gynoid (pear shape) - located in the lower extremities, waist to hip ratio: men 1.0 and women 0.8 or waist circumference: men over 40 inches and women 35
What is android fat deposit associated with?
increased risk of hypertension, insulin resistance, diabetes, dyslipidemia, and CHD
How are the different regional fats biochemically different?
abdominal fat cells:
- larger and higher rate of fat turnover than lower body fat.
- Abdominal adipocytes are hormonally more responsive than fat in the legs or butt
- FAs taken up by the liver could lead to insulin resistance and increased synthesis of TAGs which are released as VLDL
gluteal fat:
-FFAs from gluteal fat enter the general circulation and there is no preferential action on hepatic metabolism
difference between subcutaneous fat and visceral fat?
sub - generally harmless
visceral - in abdomen including around the liver, stomach and intestines promotes inflammation and metabolic disturbances and it is associated with health complications like type 2 diabetes and heart disease.
What are the changes that occur in the accumulation of fat?
- increase in the number of cells
- increase in the size of the cells
it is easier to reduce the size fo the cells
Hypertrophic vs hyperplastic fat cells?
trophic - size
plastic - number of cells
Weight …… following episodes of overfeeding or underfeeding but …… to the set point
changes
but geos back to the
Main cause in the rise of obesity ?
cant be genetic factors and chemical or hormonal factors because they are the same.
- main cause is the food industry in which a lot of our food now has additives and perservatives and we like to enjoy food. We use food as a dopamine hit
obesity behaves as a …. ….. …. with multiple ….. involved
complex polygenic disease with multiple genes involved
mutation of what genee can cause obesity?
The gene that contorls leptin, if there is leptin deficiency you can become obese
What is leptin?
An adipocyte peptide hormone that is made and secreted in proportion to the size of fat stores. More fat means more leptin.
What genes are associated with obesity?
Ob gene
Why is the Ob gene so important in obesity?
-because it produces leptin which acts on the satiety centre (hypothalamus)
what is so important about the db gene ?
- mutation in the db gene will cause leptin resitance in which many obese people have leptin resitance
- leptin decreases appetite
- insulin also decreases appetite
signals that are sent by the hypotahlamus when underenourished
if no leptin, this is not controlled
signals sent by hypothalamus when overnourished ?
if no leptin then it is not controlled
Hormones that impact obesity?
ghrelin - appetite stimulating
cholecystokinin (CCK) - saiety signal
insulin - increases metabolism and decreases energy intake
What are the primary metabolic effects of obesity?
- dyslipidemias
- glucose intolerance
- insulin resistance expressed primarily in the liver, skeletal muscle, and adipose tissue
- meetabolic syndrome
- non alcoholic liver disease
What is the metabolic syndrome and what is it associated with?
charecterised by obesity, especially abdominal obesity
associated with:
- hypertension
- insulin resitance - hyperglycaemia and high levels of insulin
- low levels of HDL but high levels of TAG and high levels of small, dense and atherogenic LDL
- elevated plasma concentration of non esterfieed FAs
- low grade systemic inflammation with high levels of circulating inflammatory cytokines
- increased oxiditave stress
- decreased fibrinolysis of blood clots
Visceral adipose tissue has ….. lipolytic activity and so it releases …… which inhibit …….. and …….
- high
- glucose metabolism
- insulin receptor signalling pathway
What does leptin antagonise?
actions of insulin
Whaat cytokines secreted by adipose tissue cause insulin resistance?
- TNF-alpha
- interleukins IL-1 and IL-6
- monocyte chemotactic protein and resistin
cortisol is secreted by ….. in an ….. manner
- adipose tissue
- unregulated
What does cortisol increase?
- hepatic gluconeogenesis and glucose release
- lipolysis and relase of non esterfied FAs in adipose tissue
What is dyslipidemia?
- insulin resitance in adipose tissue causes increased activity of hormone sensitive lipase whic leads to an incerase in circualting FAs
- FAs are carried to the liver where it is converted to TAGs and cholestrol
- These are released as VLDL and results in increase in serum TAGs
- HDLs are decresased
What is non alcoholic liver disease?
- it is when obesity is associated iwth ectopic deposition of TAG in the liver and this leads to hepatic steatosis
- results in increased risk of non alcoholic fatty liver disease (NAFLD)
What are some health risks of obesity?
- ) cancer - breast, prostate and colorectal
- ) atherosclerosis - CHD, high blood pressure, and stroke
- ) complciations of T11 DM
- ) respiratory disease
As more food is eaten what increases ?
- increased cost of digestion
- increased cost of absorption
- increased cost of synthesis of TAG and glycogen reserves
- increased protein turnover
as body weight increases what else increases?
- increased BMR
- increased cosst of physical activity
What is the initial rapid weight loss associated with?
- loss of water associated with glycogen
