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Obesity General Information

  • Last modified date:
    1 February 2011


What is overweight and obesity?

Overweight and obesity are clinical terms used to describe excess body fat.

How do we measure obesity and overweight?

The most common method of measuring obesity is the Body Mass Index (BMI). BMI is calculated by dividing a person’s weight measurement (in kilograms) by the square of their height (in metres).

In adults, a BMI of 25 to 29.9 means that person is considered to be overweight, and a BMI of 30 or above means that person is considered to be obese.

In children and adolescents BMI varies with age and sex, for this reason, the BMI score for children and adolescents is related to the UK 1990 BMI growth reference charts in order to determine a child’s weight status.

BMI is the best way we have to measure the prevalence of obesity at the population level. No specialised equipment is needed and therefore it is easy to measure accurately and consistently across large populations. BMI is also widely used around the world, not just in England, which enables comparisions between countries, regions and population sub-groups.

For most people their BMI correlates well with their level of body fat. However, certain factors such as fitness, ethnic orgin and puberty can sometimes alter the relation between BMI and body fatness. In cases such as this other measurements such as waist circumference and skin fold thickness can also be collected to confirm a person’s weight status.

How many people are overweight or obese in England?

The latest Health Survey for England (HSE) data shows that in 2009, 61.3% of adults (aged 16 or over), and 28.3% of children (aged 2-10) in England were overweight or obese, of these, 23.0% of adults and 14.4% of children were obese.

The Foresight report, Tackling Obesities: Future Choices project, published in October 2007, predicted that if no action was taken, 60% of men, 50% of women and 25% of children would be obese by 2050.

Why are people obese?

Essentially, excess weight is caused by an imbalance between energy in – what is consumed through eating – and energy expenditure – what is used by the body, over a prolonged period. Therefore, it is an indvidual’s biology (e.g. genetics and metabolism) and/or behaviour (eating and physical activity habits) that are primarily responsible for maintaining a healthy body weight.

However, there are also significant external influences such as environmental and social factors (e.g. changes in food production, motorised transport and work/home lifestyle patterns) that predispose body weight.

Why is it important to reduce obesity?

Obesity has a severe impact on the health of individuals, increasing the risk of type-2 diabetes, some cancers, and heart and liver disease.

Around 10% of all cancer deaths among non-smokers are related to obesity. The risk of Coronary Artery Disease increases 3.6 times for each unit increase in BMI. And the risk of developing type 2 diabetes is about 20 times greater for people who are very obese (BMI over 35), compared to individuals with a BMI of between 18 and 25. These diseases can ultimately curtail life expectancy. Some studies have shown that severley obese individuals are likely to die on average 11 years earlier than those with a healthy weight, although this figure can vary depending on an indvidual’s circumstances.

Given the impact on indvidual health, obese and overweight individuals also place a significant burden on the NHS. Direct costs are estimated to be £4.2 billion and Foresight  have forcasted that this will more than double by 2050 if we continue as we are. But there are also costs to society and the economy more broadly – for example, sickness absence reduces productivity. Foresight estimated that weight problems already cost the wider economy in the region of £16 billion, and that this will rise to £50 billion per year by 2050 if left unchecked.

What is the Government doing to reduce obesity?

Obesity is a priority for the Government. We want people to know that they can change their lifestyle and make a difference to their health. What the Government can do is give the public clear, consistent messages on why they should change their lifestyle, how to do so, and put in place ways to make this easier. 

The White Paper, Healthy Lives, Healthy People: Our strategy for public health in England set out radical plans for how the Government will improve public health and tackle today’s causes of premature death and illness, including obesity.

We will do this by creating Public Health England which will give more power to local people to improve their health.  There will be a ring-fenced public health budget and Local Authorities will commission the majority of public health services.

We want to give individuals, families and communities the responsibility and information they need to improve their own health. This includes reducing the levels of obesity by promoting greater physical activity and a healthier diet.

The Government will facilitate and support people to make informed decisions about their lifestyle and health, working alongside providers and others in the private and voluntary sectors.

The Change4Life campaign continues to help individuals and families to eat well and move more. The National Child Measurement Programme provides parents with information on their child’s weight and supports parents to make positive changes that will affect their child’s long-term health.

In spring, the Department of Health will publish a follow-on document to Healthy Lives, Healthy People which will set out how obesity will be tackled in the new public health and NHS systems, along with the role that all partners can play.

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