Obesity

Matt Jarvis

Obesity

Why is obesity a concern?

• Obesity is an excess of body fat that is

associated with risks to health.

• It is associated with a higher risk of

diabetes, heart disease and cancer.

Obesity is much more common now than in the past.Three in four UK adults carry too much fat.

Obesity

Why has obesity increased?

The obesogenic environment is believed to be the main factor.

This is an environment containing many tasty high-calorie foods.

Factors in the obesogenic

environment include:

• Larger portion sizes

• Marketing of unhealthy foods

• Cheaper energy-rich food

Obesity

Genetic influences on weight

It is apparent that not everyone is overweight in spite of the

obesogenic environment. This suggests there are genetic

differences in how we respond to food.

Twin studies

Identical twins are much more similar in weight than non-

identical twins. This suggests weight is largely genetically

controlled.

Obesity

Genetic risk of obesity

Several genetic variations have been identified that are

associated with weight. The first was the FTO gene.

The high-risk FTO

gene carries a 50%

increased risk of

obesity

Several other risk-genes have

been identified. The more of

these we have the more likely

we are to be obese

Obesity

Inherited behavioural risk

Two major factors have been identified:

• Food responsiveness: some people are more

tempted by food-cues so are more likely to indulge

• Satiety signalling: some people do not realise

they are full and so tend to over-eat

Obesity

Conclusions

• Both genetic and environmental influences impact on obesity.

• Where the environment is rich in high-energy food, obesity

levels will probably always be high.

• Some individuals are particularly susceptible to the

temptation to over-eat as a result of their genetic make-up.

• Some individuals are particularly vulnerable to over-eating as

they do not respond to fullness as a result of their genetic

make-up.

• There are a range of strategies to limit over-eating.