Overweight and Lack of Exercise Linked to Increased Cancer Risk

In both industrialized and industrializing countries, overweight and obesity have become increasingly common over the last two decades, and in western countries it has reached epidemic dimensions. In the USA, one quarter of Americans were overweight in 1978, and in 1990, one third were overweight. The latest figures show that 60% are now overweight. In Europe, about half the adult population is currently overweight, and urban areas of many developing countries have a similar prevalence.

Overweight measurement is provided by the body mass index (BMI), calculated by dividing the body weight (in kg) by the height squared (m2). Thus, an adult who weighs 100 kg and is 2 m tall has a BMI of 25. The World Health Organization considers a BMI of less than 18.5 to be an indicator of underweight, whereas a BMI >25 indicates overweight and >30, obesity. The normal, desirable range is from 18.5 to 25. For an adult of 1 m 75, therefore, this weight range would be from 57 to 77 kg. (Height: 5ft 7in., weight range from 125.6 lb- 169.7 lb).

The reasons for the epidemic are not hard to discover. The fundamental causes of the obesity and overweight lie in sedentary lifestyles and over-consumption of high-calorie food. Body fat is a consequence of an imbalance between calorie intake and expenditure, both of which have strong cultural and behavioural components. The importance of physical activity as a determinant of body weight is well known. Children in western countries are less physically active than in the past, both at home and at school.

The consequences of the epidemic of overweight and obesity are now being realized. Overweight and insufficient physical activity are associated with several chronic illnesses, including cardiovascular disease and adult-onset diabetes. Their role in cancer development was evaluated by a panel of international experts convened by the International Agency for Research on Cancer, of the World Health Organization (WHO) in Lyon on 13