In the Pharmaceutical Times report Mark Greener, a former pharmacologist, says money is wasted treating the results of obesity rather than tackling its causes.

"The UK spends around �195m treating obesity-related diseases," he writes.

But only 15% of this goes on tackling obesity itself, he adds.

In the UK, 13% of men and 16% of women are obese, the report says. Overall, 57% of men and 48% of women are overweight.

Obesity can cause heart disease, high blood pressure, cancer and diabetes. It also increases the risk of psychological problems.

The report adds that, on questioning, obese people admit to a worse quality of life than those who have had multiple amputations or who are severely disabled.

Defining the condition

Research has also established that the number of obese people in the developed world has been rising steadily for some time.

Yet effective treatments are hard to come by, according to the report.

There is no consensus on an exact definition of obesity, but doctors agree that it is not the same as simply being overweight.

The main cause of obesity is eating too much combined with a lack of exercise.

Obesity can be seen as the extreme end of a scale that starts at underweight.

It is measured using the body mass index (BMI). This is calculated as a person's mass in kilograms divided by the square of their height in metres.

So someone whose mass was 92kg and whose height was 2m would have a BMI of 23 - 92 divided by 4. This falls in the "normal" range on the BMI scale.

The position of the excess fat also makes a difference - fat around the abdomen poses a far higher health risk than fat in the thighs or other parts of the body.

For example, an extra centimetre of fat on the abdomen doubles the risk of heart problems.

Drug treatments

The search for a cure for obesity is big business, but has suffered setbacks.

Last year, two drugs were withdrawn after it was found that they caused heart problems in some patients.

However, a drug launched this year offered new hope for severely overweight patients.

Xenical, the brand name for the drug orlistat, has been available in the UK since September after it won approval from EU regulatory authorities.

The drug works by blocking the digestion of fat in the gut. It has to be taken as part of a low-fat diet. People taking the pill on a high-fat diet will get a bloated and painful stomach and suffer oily diarrhoea.

However, Mr Greener writes: "Orlistat will not be the last drug for obesity, it is too big a problem for that."

Although several other treatments are in development, they will not be ready for many years and the health service will have to focus on encouraging people to adjust their lifestyles, he concludes.