Etiology of Obesity

Question 1

definition of etiology

Answer 1

the cause, sets of causes or manner of causation of as disease or condition

Question 1

what we know in the etiology of obesity has been based on what

Answer 1

predictive research (observational/ cross sectional studies)

Question 2

what 2 factors are critical for the development of obesity to occur

Answer 2

environment & genetics

Question 4

how can ‘set points’ increase

Answer 4

receptors involved in feeding and regulation of metabolism may be deleted in their brain (MCR 4)

Question 4

how do genetics play a role in obesity

Answer 4

Heritable factors appear to be responsible for a large proportion of the inter-individual variation in BMI (up to 75%)

Question 4

In research what had a strong correlation to weight class/BMI & what had no correlation

Answer 4

-Strong correlation between weight class of adoptees and the BMI of their biological parents
-No correlation between weight class of the adoptees and BMI of the adoptive parents.
-Genetic influences play an important role in determining level of fatness, whereas the environment alone was found to have no significant effect

Question 5

What mutations in genes are involved in appetite control & where are they found & invovled in what

Answer 5

MCR4 , lepin deficiency leads to intense hyperphagic and food seeking behaviours. Found around CNS and involved in functional & structural aspects of neurotransmission.

Question 6

define syndromal obesity

Answer 6

severe form of obesity that occurs with other clinical features.
- Medical syndromes associated with increased probability for obesity.

Question 7

what are some syndromal obesity syndromes (6)

Answer 7

1. Prader-Willi Syndrome
2. Bardet-Biedl Syndrome
3. Cohen syndrome
4. Cushings disease
5. hypothyroidism
6. pseudohypoparathyroidism

Question 8

How can obesity be the result of genetics for genes do not change very fast

Answer 8

epigenetic expression

Question 9

define epigenetics

Answer 9

How your behaviours and environment can cause changes that affect the way your genes work.
- Can explain how a gene can be ‘switched on and off’ literally overnight

Question 10

What was found in the baby with the mother starvation during the 1st and 3rd trimester

Answer 10

In the first 3 months (1st trimester) in the womb a developing fetus (when its brain is developing) who senses its mother malnourished ‘wires’ its brain to be hungrier and more fuel efficient

Question 11

define interaction

Answer 11

a situation in which the response/adaptation to a change in behaviour/ the environment is conditional on the genotype of the individual.
-synergistic effect between 2 variables to create the result

Question 12

examples of environmental factors (epigenetics)

Answer 12

-intrauterine environment (in the womb)
-drugs
-sleep quality/chronic sleep deprivation
-chemicals
-aging
-resistence traing
-diet

Question 13

gardening pot analogy for interaction

Answer 13

You have 3 planter pots outside, all different sizes. It rains over night & all pots are filled (environment). Each pot has a pre-determined capacity because of how they were made/built (genes).

Question 14

How does ‘interaction’ relate to higher risks of obesity

Answer 14

higher obesity risk may result between genes & our lifestyle/environment.
Ex. FTO gene (fat mass and obesity gene). Shows a strong association with BMI, obesity & fat mass

Question 15

Those with the FTO gene are more likely to… (3)

Answer 15

1. weigh 3-4kg more on average
2. have 1.67x the risk of developing obesity compared to the non risk genes
3. quite prevelent amoung caucasians

Question 16

what is a Genome Wide Association Study (GWAS)

Answer 16

A research approach used to identify genomic variants that are statisically associated with a risk for a disease or a particular trait (tells you if you have a biological predisposition to something)

Question 18

What issues could genetic testing raise? (2)

Answer 18

-Could cause for additional worrying about possible future disease/disability
-If insurance can view your genetic predisposition it could cause you not to get covered for something.

Question 19

I s it possible to change your set point?

Answer 19

yes, but it is difficult to maintain it

Question 20

Are there certain points in our life that may be more or less critical for our set point?

Answer 20

-N/A
-There is no current research

Question 21

Is it possible that everything we do on a regular basis could be contributing to our genetic expression?

Answer 21

Yes, like sleep quality, exercise and diet. Basically how we set up our environment.

Question 22

describe the general model of obesity. Social + built environment, Obesogenic environment (over eating, sedentary behaviour, low levels of PA), biological predisposition(high-medium-low), positive energy balance, weight gain

Answer 22

-social + built environment influence our obesogenic behaviours
-obesogenic behaviours effect our biological predisposition which effect the positive energy balance which leads to weight gain
-If we have a high biological predisposition we have a higher chance of gaining weight (easier to gain weight), if we have a low biological predisposition then we have a lower chance at gaining weight (not as easy to gain weight)

Question 23

why do people exposed to the same obesogenic behaviours not develop obesity

Answer 23

biological predisposition

Question 24

what is the predominant factor leading to obesity

Answer 24

genetic predisposition. Either classic genetic mutation or epigenetic modification of gene expression.
“genes load the gun, the environment pulls the trigger”