Genetic Epidemiology Of Obesity

Question 1

Behavioural susceptibility theory

Answer 1

• theory that body weight is determined by appetite
• can be due to food responsiveness (hedonic traits and reward sensitivity towards food)
• can be due to satiety responsiveness (reflects homeostatic control of appetite)

Question 2

Behavioural susceptibility theory: is appetite heritable?

Answer 2

• twin studies can shed light
• show important genetic contribution towards appetite of ~63-75%
• heritability of appetite remains constant over 10 years

Question 3

Behavioural susceptibility theory: does appetite cause weight gain?

Answer 3

• meta analysis showed that those more food responsive and less satiety responsive had higher BMIs
• graded response evident in TEDS database

Question 4

Behavioural susceptibility theory: do genes influence weight through appetite?

Answer 4

• 28 SNPs identified in the TEDS database relating to satiety responsiveness
• the more at risk alleles a child had, the more likely will have a higher BMI

Question 5

Behavioural susceptibility theory: how is appetite expressed behaviourally?

Answer 5

• questionnaire to parents on the TEDS database
• looked at diet diaries
• those children with lowest satiety responsive ate 185 kcal more per day versus those with high responsiveness
• those with more food responsiveness ate 3 more meals per week

Question 6

Behavioural susceptibility theory: influence of the environment

Answer 6

• children in an obesogenic environment (ie little PA, more junk food, more screentime) had a greater heritability of higher BMI
• those in health-promoting environments behaved as a buffer towards genetically determined higher weight