England is laid waist by a nation of fatties

'WE began as hunter-gatherers. Now we're couch potatoes." In these two, trim sentences, Dr Jeffrie Strang explains why Britain is getting fatter. It is, of course, a lot more complex than that. But the reason obesity has tripled in the last 20 years is as much to do with our lack of exercise as poor diet.

"All the evidence suggests we are not eating more," says Dr Strang, consultant in public health medicine at North Yorkshire Health Authority. "Calorie intake is possibly a bit less than it was 25 years ago.

"But we take even less activity than we did.

"I'm not saying obesity is not about over-eating. But there's a balance between putting energy in and taking energy out."

Our lifestyle is increasingly sedentary. "Today we don't even have to turn the key in the ignition of some cars. We don't have to walk upstairs to shops, we use the escalator. We don't even have to open the door to some shops.

"We don't have to get up to change the telly channels."

The result: a large proportion of the nation is getting larger. According to Tackling Obesity In England, a report by the National Audit Office, one in five adults is now obese. The problem is set to grow further, with that figure predicted to reach one in four by 2010.

Add in the numbers for those who are merely overweight, and the figures reveal that two-thirds of men and more than half of women need to shape up. That's 20 million adults.

Children are not faring much better. A report published last week revealed that the numbers of overweight and obese pre-school children is growing.

Many serious health problems are associated with obesity. High blood pressure, mature onset diabetes, heart disease, arthritis, even some types of cancer are more likely to affect someone who is seriously overweight.

The economic price is high, too, according to the audit office. They put the cost to the NHS at £500 million, and lost working days at 18 million.

The report said that only one in seven health authorities had a plan to prevent and treat obesity. "We don't have a strategy document to treat obesity as such," Dr Strang said.

"It tends to be linked with strategies to tackle heart disease, diabetes etc."

North Yorkshire Health Authority also works with primary health care groups and NHS trusts on programmes to encourage physical activity and diet awareness.

But in the end, fat is not purely a health service issue. It's one for society at large to tackle, said Dr Strang. Councils can encourage exercise by providing safe cycle lanes. Schools and companies can serve up healthy meals in canteens. More time can be devoted to PE and what used to be called home economics on the school curriculum.

And overweight people have to decide for themselves whether they want to slim down. If they do, they must find a way to shed the pounds and keep them off.

That is not easy, as Anne Robinson, dietetic manager at York District Hospital acknowledges. Obesity happens slowly and "it requires a fantastic behaviour change to reverse".

As we get older, she explained, we need fewer calories. Someone who is in their fifties may need between 200 and 400 calories a day less than they did in their thirties. That is because the body does not replenish its cells and organs so quickly after reproductive age, and so burns less energy.

But many people do not adjust their lifestyles accordingly.

She also said weight distribution made a difference, as characterised by apple and pear-shaped bodies.

"The health risks are more associated with the apple shape. If you carry a lot of fat round your middle, it's a more dangerous situation to be in than if you carry it around your hips.

"If you can get your middle to come down by two inches, that's a positive health gain. If you can lose in the order of ten kilograms about 22lbs and keep it off, that's a positive health gain."

But that doesn't mean you have to sign up for a gym or get a personal trainer, as TV presenter Vanessa Feltz famously did. Instead, try to take a walk as often as possible.

"It doesn't need to be for hours and hours. Just make exercise part of your life," says Anne

As for food, yo-yo diets, involving periods of near starvation, damage valuable muscle and are positively unhealthy.

Instead, organise your meals around those five portions of fruit and vegetables we are all supposed to eat.

Keeping the weight off is the hardest part. Only one in ten successful slimmers at slimming classes stick to their ideal size.

It is easier to prevent the problem in the first place, Anne said. So don't teach your children fat habits.

Updated: 11:48 Friday, February 16, 2001