London - As dieting mantras go, it could not be any simpler. All you need to do to lose weight is eat less fat and do more exercise.

And the secret to successful slimming is so straightforward it has been dubbed the ‘Not Rocket Science’ diet.

The diet industry is booming, with research suggesting the average woman spends nearly £500 (about R6 000) a year on health foods, equipment, clothing and membership fees for gyms and slimming clubs to try to lose weight.

But research suggests there could be a simpler solution.

A team of scientists at Harvard Medical School in Boston studied 4,000 obese adults and found those who followed the common sense advice were much more likely to lose weight than those who adopted fad slimming regimes, went on liquid diets or bought weight loss supplements.

Two-thirds of the group said they had tried to lose weight in the previous year through a variety of diets.

The researchers found 41 percent of those who cut their fat intake were more likely to have shed five percent of their body weight in under a year than those who went on liquid diets, used non-prescription dieting supplements or followed popular slimming regimes such as the Dukan or Atkins diets, which combine high protein intakes with relatively large amounts of fat.

And if they exercised more than usual, they were almost 30 percent more likely to lose the weight, the study, published in the American Journal of Preventive Medicine, found.

Although five percent weight loss may not sound significant, experts say it is enough to delay the onset of diabetes in an obese person.

And the ‘Not Rocket Science’ diet helped many volunteers shed more weight, with 37 percent of those who cut down on fat more likely to lose a tenth of their body weight, while exercising boosted their chances by 36 percent.

The researchers did also notice significantly greater weight loss among those who took prescription diet medications, which doubled the chances of 10 percent weight loss.

But the drugs are not cheap, with the NHS in England spending around £47 million a year on medicines to fight obesity. Nearly a quarter of adults and one in seven children in Britain are estimated to be clinically obese, raising the risk of cancer and heart disease.

It is estimated that treating weight-related medical problems costs the NHS £4 billion a year.

Doctors are so concerned that the medical royal colleges – representing nearly 200,000 clinicians – have joined forces in a campaign to tackle weight-related ill health.

Researcher Dr Christina Wee, who helped compile the study, said: “There are lots of fad diets out there as well as expensive over-the-counter medications that have not necessarily been proven to be effective.

“So it’s very encouraging to find that most of the weight loss methods associated with success are accessible and inexpensive.”

Dr David Haslam, chairman of the National Obesity Forum, said the Not Rocket Science diet sent out “a good message”.

But he added: “Whatever works in the short-term will only be a success if it also works in the long-term. These changes to physical activity and dietary intake have got to be sustainable.” - Daily Mail