What is Obesity?
Obesity is most easily defined as a raised body mass index (BMI). The BMI is the weight in kilograms divided by the height in metres squared. A normal and healthy BMI is between 18.5 and 24.9kg/m2. A BMI less than 18.5kg/m2 is underweight and unhealthy. Similarly, a BMI greater than 25kg/m2 is overweight and unhealthy. Body mass indices above 25 are sub-classified as overweight or obese: such that 25-30 is overweight and greater than 30 is obese. The obese category is further sub-divided with 30-35 kg/m2 as grade 1 obesity, 35-40 kg/m2 as grade 2 obesity and 40 kg/m2 or above as grade 3 or morbid obesity.
To take into consideration the fact that athletes, with low levels of body fat, having more muscle mass than non-athletes, may be erroneously classified as overweight or obese by the BMI alone, the waist circumference, approximately measured at the umbilicus (belly button), is used to support the BMI as evidence of obesity. Moreover, it is recognised that central fat held around the abdomen produces more unhealthy substances than peripheral fat and acts as a toxic inflammatory organ.
BMI and Classification
- Underweight: less than 20kg/m2
- Normal Weight: 20-25kg/m2
- Overweight: 25 to 30kg/m2
- Obese: 30kg/m2 and above
- Morbidly Obese: 40kg/m2 and above
Prevalence of Obesity
Presently, in the UK some 33% (1 in 3) adults are obese. This represents a phenomenal 380% increase over the last 30 years given that only 8% of adults were obese in 1980. According to the recent Foresight Report, at the current trend, about 50% of the UK adult population will be obese by 2050!! More worrying is the children population which has also seen fantastic rises in the rates of obesity.
Health Consequences of Obesity
Every year, as many as 30,000 people die prematurely from obesity-related conditions, with some experts now warning that obesity is responsible for more ill health than smoking such that we should begin to treat obesity in the same way that smoking is now treated, i.e. universally accepted as unhealthy. Being significantly overweight or obese is linked to a wide range of health problems, including:
- Cancers (e.g. breast, liver and prostate)
- Heart disease
- High blood pressure
- Liver disease and liver cancer
- Pancreatitis and possible pancreatic cancer
- Snoring and obstructive sleep apnoea
- Stress, anxiety, and depression
Regarding the liver, obesity is now the commonest cause of chronic liver disease in the UK.
Costs of Obesity
A study by the National Audit Office estimates that obesity is currently costing the NHS at least £5.1bn per year and costing the wider economy more than £20bn a year, through lost productivity. Given the phenomenal rate of increase of obesity rates and that the epidemic shows no sign of slowing, this cost burden will only worsen.
Causes of Obesity
Obesity is caused simply by an imbalance between energy intake and energy expenditure. The average adult needs about 2000kCal/day. Any excess intake over this is stored by the body. Continued excess calories input therefore over time results in obesity. Excess intake of calories is facilitated by the high calories content of many convenient and mass-produced foods along with over-large food portions. Additionally, the increase in sedentary lives and a reduction in exercise are to blame. In Support of this, a recent study showed that homemakers in the 1950s ate more calories than their modern counterparts, but were significantly slimmer because their daily lives involved greater physical activity.
As with most things in medicine, ‘prevention is better than the cure’. A combination of a healthy, balanced diet and regular exercise is sufficient in the majority of cases. Experts recommend vigorous exercise such as brisk walking, swimming or cycling five times a week for 20-30 minutes.
For patients, however, who are already obese; weight management clinics are available to provide expert help and advice. In severe cases, doctors may prescribe drug therapies, which have been shown to have some positive impact. Endoscopic or surgical management is usually reserved for the most extreme cases, as they can be risky and patients may require life-long monitoring for potential complications.
Endoscopic options include procedures such as the intra-gastric balloon which induces a sense of fullness, and the endosleeve which reduces food absorption. Surgical options include the gastric band which reduces the size of the stomach, meaning that less food can be ingested and subsequently patients feel full quicker and so eat less.