The optimum weight for adults is frequently assessed using a measure known as the body mass index (BMI), calculated by dividing weight (in kilograms) by height (in metres) squared (kg/m2) Individuals with a BMI 25-29.9 are classified as being overweight. Those with a BMI of 30 or above are classified as obese. (1)

Assessing the optimum weight for children is more complex. Children's BMIs are dependent on age and sex. Centile charts, based on the BMIs of a large number of children, are a commonly used method of comparing individual children with their peers. The 50th centile represents the average. A child with a BMI above the 50th centile has a higher than average BMI. Children above the 85th centile are viewed as overweight, while those above the 95th are classified as obese.

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Individuals gain weight through consuming more calories than they use. The excess calories consumed are stored by the body as fat.

Although some medical conditions may lead to weight gain, these are not significant contributors to the rapidly increasing levels of obesity seen over recent years. This has been due primarily to changes in society's dietary patterns and levels of physical activity.

The increasing consumption of energy dense foods such as confectionary and soft drinks, which contain a high calorie content relative to their weight, is partly responsible. Such foods do not lead to a sense of 'fullness' (satiety) and can therefore contribute to overeating. Alcohol can also contribute through providing substantial amounts of calories, again without leading to satiety. Decreasing levels of physical activity result in decreased calorie use.

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The UK Public Health Association and the Faculty of Public Health describe obesity as "…an excess of body fat frequently resulting in a significant impairment of health and longevity." (2) A number of diseases are more common in overweight and obese people, including:

Not only does obesity increase an individual's risk of certain illnesses, it also affects their life expectancy. A recently published study suggested that 8.7% of deaths in UK were a consequence of excess weight (3). It is estimated that obese individuals on average die nine years earlier than non-obese people. Being overweight, but not obese, also increases the chance of d eveloping or dying from the above diseases but the risk is lower than for obese people.

There are also economic consequences. In England in 2002, it is estimated that the costs associated with treating obesity and its associated disorders, and dealing with its indirect consequences (e.g. sickness absence),were £3.3-3.7 billion.(4)

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The Health Survey for England [HSfE] (5) collects information on a number of factors, including BMI. Based on information derived from the HSfE, the graphs below show the percentage of adults (aged 16yrs and over) overweight or obese in London and England.

Date	Title	Format	View
11 Jan 2005	Percentage of Adult Population Obese - London & England
11 Jan 2005	Percentage of Adult Population Obese - London SHA's & England
11 Jan 2005	Percentage of Adult Population Overweight - London & England
11 Jan 2005	Percentage of Adult Population Overweight - London SHA's & England

It can be seen that the proportion of obese adults in both London and England has increased significantly over recent years. Unfortunately, no sub-national data for children is available. However, national estimates suggest that 16% and 14% of English children aged 2-15 years were obese and overweight respectively in 2002. (5)

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The recent House of Commons Health Committee (4) and Royal College of Physicians (6) reports made a number of recommendations for tackling obesity. They suggested a combination of measures, some targeted at individuals to encourage lifestyle change (e.g. public education campaigns promoting physical activity and reducing the consumption of energy dense foodstuffs) with others aimed at addressing environmental factors (e.g. increasing opportunities for people to become more physically active). They also recommended that the NHS should incorporate the prevention and management of overweight and obesity into health service plans, policies and strategies.

Date	Title	Format	View
30 Apr 2009	National Child Measurement Programme: detailed analysis of the 2007/08 dataset
9 Oct 2007	Summary points from the 07/08 NCMP guidance
26 Sep 2007	The national child measurement programme guidance for PCTs: 2007-08 school year
18 Jun 2007	National Child Measurement Programme(NCMP) Data-Capture Tool
11 May 2007	Measuring childhood obesity: guidance to PCTs on data handling
25 Aug 2006	Forecasting Obesity to 2010
30 May 2006	Lightening the Load: Tackling Overweight and Obesity
13 Jan 2006	British Heart Foundation Statistics: Prevalence Of Obesity By Sex & Ethnicity (England, 1999)
13 Jan 2006	Choosing A Better Diet - A Food and Health Action Plan
13 Jan 2006	Faculty of Public Health
13 Jan 2006	Government Press Release: Healthy Food in Schools - Transforming School Meals
13 Jan 2006	Government Response to the Health Select Committee’s Report on Obesity 2004
13 Jan 2006	Health Survey For England 2002 - Childhood Obesity
13 Jan 2006	Health Survey for England 2003: Risk Factors for Cardiovascular Disease
13 Jan 2006	International Obesity Taskforce
13 Jan 2006	National Expenditure & Food Survey
13 Jan 2006	National Food Survey
13 Jan 2006	National Obesity Forum
13 Jan 2006	World Health Organisation (WHO) obesity webpages
12 Jan 2006	Measuring Childhood Obesity. Guidance to Primary Care Trusts
26 Oct 2005	Monitoring Childhood Obesity in London
6 Jun 2005	Choosing Health Implementation Plan for Obesity, Healthy Diet and Physical Activity
6 Feb 2005	Choosing health. A briefing on nutrition, physical activity and obesity in London

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• Food Standards Agency (FSA)
• Department for Environment Food and Rural Affairs
• The Scientific Advisory Committee on Nutrition
• Sustain: the alliance for better food and farming
• The British Dietetic Association
• 5-a-day programme (NOT LIVE AS YET). This will be a national website with a London section outlining information and case studies specific to London. Due for completion by autumn 2005. For more information contact , 5-a-day co-ordinator in London.
• Healthy Schools Programme. National site. Click on the London section for activities, information and contacts specific to London
• Healthy Weight Healthy Lives
• HWHL guidance for local areas
• Healthy living social marketing initiative: a review of the evidence
• Foresight report
• National Obesity Observatory for England

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1. Management of obesity in children and young people. A national clinical guideline.
2. UK Public Health Association and Faculty of Public Health Medicine
3. Banegas R, et al. A simple estimate of mortality attributable to excess weight in the European Union. European Journal of Clinical Nutrition 2003;57:201-209.
4. Obesity. House of Commons Health Committee. The Stationary Office, London - 2004.
5. Health Survey for England
6. Storing up problems. The medical case for a slimmer nation. Report of a working party of the Royal College of Physicians, Royal College of Paediatrics and Child Health and the Faculty of Public Health. February 2004.

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