Abdominal obesity refers to the presence of excess fat in the abdominal area (also known as excess abdominal adiposity). Its presence indicates a higher likelihood of developing a range of diseases including cardiovascular disease, cancer and diabetes.
Waist circumference is the most practical marker of abdominal fat. (Many people understand this concept as the 'apple' versus 'pear'-shaped body.) A waist circumference greater than 88 cm (more than 35 inches) in women and 102cm (more than 40 inches) in men indicates an increased risk of cardiovascular disease. (Obesity: the prevention, identification, assessment and management of overweight and obesity in adults and children. NICE clinical guideline 43).
Diabetes is a group of disorders with a number of common features characterised by raised blood glucose. In England the 4 commonest types of diabetes are:
type 1 diabetes
type 2 diabetes (this accounts for more than 85% of all incidences of diabetes)
secondary diabetes (from pancreatic damage, hepatic cirrhosis, endocrinological disease/therapy, or anti-viral/anti-psychotic therapy)
gestational diabetes (diabetes during pregnancy).
Diabetes is caused when there is too much glucose in the blood and the body cannot use it as 'fuel'. This can happen because the pancreas does not produce any (or sufficient) insulin to help it to enter the body's cells. Or the problems may be caused because the insulin produced does not work properly (insulin resistance).
For the purpose of this guidance, 'lifestyle interventions' refers specifically to activities encouraging physical activity and a healthy diet, as described in Preventing type 2 diabetes: risk identification and interventions for individuals at high risk (public health guidance 38): recommendations 7–14.
'Metabolically active' fat (also known as visceral fat adipose tissue) is associated with a variety of physiological responses including insulin resistance, pre-diabetes and type 2 diabetes (Banerji et al. 1999; McKeigue et al. 1991, 1992, 1993; Nesto 2005). This type of fat can also impair the functioning of blood vessels (Nesto 2005).
A cluster of metabolic risk factors including: insulin resistance, hypertension (high blood pressure), cholesterol abnormalities and an increased risk for clotting. People with all of these factors are usually overweight or obese. The syndrome is associated with an increased risk of diabetes mellitus and cardiovascular disease.
BMIs of 23 kg/m2, 27.5 kg/m2, 32.5 kg/m2 and 37.5 kg/m2 are recommended as 'public health action points' by the World Health Organization. These are the triggers for health professionals to intervene to help Asian people manage their weight through, for example, physical activity and healthy eating. The categories WHO suggests for people from Asian groups are: 18.5–22.9 kg/m2 (increasing but acceptable risk); 23–27.4 kg/m2 (increased risk); and 27.5 kg/m2 or higher (high risk of developing chronic health conditions).
The point at which people in each of the groups being compared are equally likely to experience the same outcome (for example, myocardial infarction).