1. Obesity Matt Jarvis

2. 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.

3. 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

4. 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.

5. 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

6. 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

7. 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.