Key points

  • Obesity is a condition in which abnormal or excessive fat accumulation in adipose tissue impairs health.
  • Overweight and obesity are usually measured using body mass index, although waist circumference is also a useful guide. Special growth charts and associated weight recommendations exist for children.
  • In the UK and most other countries, the prevalence of obesity in adults and children has been increasing over recent decades.
  • Overweight and obesity are associated with an increased risk of developing some cancers, cardiovascular disease and type 2 diabetes.
  • A combination of more physical activity and a suitable nutrient rich but energy controlled diet is recommended for overweight/obese adults who wish to lose weight.

Obesity is a condition in which abnormal or excessive fat accumulation in adipose tissue impairs health. In most cases, it is the result of energy intake exceeding energy expenditure over a period of years. It is defined in adults as a body mass index (BMI) above 30. Within the UK the data from the Health Survey for England 2006 showed that 24% of adults (both men and women) were obese and an additional 44% of men and 34% of women were overweight (BMI ≥25-29.9).

Around 16% of children aged 2 to 15 years were obese and an additional 14% were overweight. For those aged 2 to 10 years, 16.3% boys and 14.4% girls were obese. For those aged 11-15 years, 17.6% of boys and 19.0% of girls were obese.

In contrast to these figures, in the early 1980s just 6% of men and 8% of women in the UK were obese. The recent Foresight obesity report, which looks at ways that the Government can tackle the obesity problem over the next 40 years, has projected that by 2050 60% of the UK population could be obese, creating a cost to the economy of £45.5 billion.

Obesity is no longer a disease that only affects the more developed, affluent countries. It is now a worldwide public health problem, affecting all age and socio-economic groups. In 1995 it was estimated that worldwide there were 200 million obese adults and 18 million overweight children under-five. In 2000, the World Health Organization estimated that approximately 1.2 billion people in the world were overweight, of which at least 300 million adults were estimated to be obese: around 130 million in developed countries and 170 million in other countries. Overall the increase in the prevalence of obesity has been most dramatic amongst more affluent populations living in less developed countries - those countries are said to be in transition.


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