Obesity

Epidemiology of Specific Chronic Diseases: Obesity

Definition
A number of indicators are commonly used to assess whether an individual is considered overweight or obese. These include the Body Mass Index which is defined as the weight in kilograms divided by the square of the height in meters (Kg/m2),and waist circumference.

For adults, overweight and obesity ranges are commonly determined by using the Body Mass Index (BMI). (Note: BMI does not directly measure body fat)

BMI

<18.5 - underweight
18.5 - 24.9 - healthy weight
25.0 - 29.9 - overweight
30 + -  obese
35 + -  morbidly obese
40 + -  extreme obesity

Epidemiologically speaking, children are considered overweight or obese if their BMI falls above the 85th and 95th centile, respectively, of the reference curve for their age and gender (Department of Health).

In addition, individual adult waist measurements over 102cm for men and 88cm for women are considered at increased risk of a number of diseases and medical conditions.

Health Outcomes
Individuals who are overweight or obese are at an increased risk for many diseases and health conditions including:

  • Hypertension
  • Dyslipidemia
  • Type 2 diabetes
  • Coronary heart disease
  • Stroke
  • Gallbladder disease
  • Osteoarthritis
  • Sleep apnea
  • Respiratory problems
  • Chronic musculoskeletal problems
  • Some cancers (endometrial, breast, kidney and colon)

Epidemiology

  • Worldwide there are more than 1 billion overweight adults and an estimated 300 million of them are clinically obese.
  • Obesity is a risk factor for a number of diseases and as a result obesity is a major contributor to the burden of chronic disease and disability.
  • Data from the World Health Report 2002 estimate that 58% of diabetes and 21% of ischaemic heart disease and 8-42% of certain cancers globally were attributable to a BMI above 21kg/m2.
  • Childhood obesity has increased significantly worldwide. In the United States it is estimated that the number of overweight children has doubled and the number of overweight adolescents has trebled since 1980.
  • In England, it is estimated that the prevalence of obesity has trebled since the 1980s and over half of all adults are either overweight or obese.
  • Data from the Health Survey for England (1995-2003) estimate the prevalence of obesity in children aged < 11 years increased from 9.9% in 1995 to 13.7% in 2003.
  • It is estimated that obesity is responsible for over 9,000 premature deaths per year in England.
  • In addition the National Audit Office (NAO) estimate that reducing the number of obese individuals in England by one million could lead to a reduction in coronary heart disease of 15,000, 34,000 fewer people developing type 2 diabetes and 99,000 fewer people developing hypertension (Department of Health).
  • The Health Select Committee has estimated that the costs of obesity is £3.3 - £3.7 billion per year and obesity plus overweight at £6.6 - £7.4 billion (Department of Health).
  • Obesity is more common among lower social groups.

In July 2004 a PSA target specifically on obesity was set in England - 'halting the year on year risk in obesity among children under 11 by 2010 in the context of a broader strategy to tackle obesity in the population as a whole' (Departmentof Health).

Prevention
Effective weight management
Increasing levels of activity
Promotion of healthy eating

References

  1. Department of Health, Obesity resource:
    http://www.dh.gov.uk/PolicyAndGuidance/

© CM Kirwan 2006