Never mind the fat. It's being fit that matters

A new study claims how often you visit the gym is more important than how trim you are

It is OK to be fat – so long as you are fit, according to a study. How many inches you measure round your waist may matter less than how often you visit the gym or play football.

Rising obesity is one of the world's greatest health challenges but it may be that fatness is the wrong target for concern and fitness is what really counts.

Researchers have found that up to half of people who are defined as "obese" are in fact fit and healthy and at no greater risk of becoming ill or dying prematurely than normal weight individuals.

The finding will reassure sportsmen and women who find themselves carrying a few extra pounds while maintaining a high level of performance on the field.

Brazil's soccer legend Ronaldo had a fondness for fast food and Welsh international goalkeeper Neville Southall was famous for his ample frame.

England cricketer Sir Ian Botham was happy to be known as Beefy and US golfer John Daly was no lightweight.

One of the most famous ripostes in sport involved the former Zimbabwean cricketer Eddo Brandes who was uncommonly relaxed about his weight. When Australian bowler Glenn McGrath, frustrated at being unable to get him out, tried to rile him by calling out: "Oi, why are you so fat?" Brandes responded: "Because every time I **** your wife she gives me a biscuit."

Obesity is known to be linked to a range of chronic diseases, including diabetes, heart problems and cancer and is estimated to cause 30,000 deaths a year in the UK.

But there is a group of obese individuals who are metabolically healthy, as measured by how well their heart and lungs perform, who appear to be protected from the consequences of carrying excess fat.

They account for up to 46 per cent of obese individuals, when obesity is measured by the amount of fat on the body, or up to 30 per cent when the standard measure of body mass index (BMI) is used .

A man with more than 25 per cent body fat (30 per cent for a woman) is defined as obese while for BMI, a composite measure of height and weight, a reading above 30 is considered obese. Although BMI is used universally because it is easy to calculate, body fat percentage, which is estimated from skinfold thickness, is regarded as a more accurate measure of obesity.

Some sportsmen may have a BMI above 30 even though most of their bulk is lean muscle and they carry very little fat. The study, published in the European Heart Journal, involved more than 40,000 mainly white professional people in the US who were followed from 1979 to 2003.

Those who were fit but obese had a 38 per cent lower risk of dying than those who were unfit and obese.

But there was no difference in the death rate between fit, obese individuals and those who were fit and normal weight. Dr Francisco Ortega, the chief author, now of the University of Granada, Spain, said: "We should stop worrying about fatness and worry more about fitness."

A second study in the journal suggests that being overweight may protect people who have already developed heart disease.

This is the so-called obesity paradox – patients with heart disease who try to lose weight may actually increase their risk of dying.

The findings are based on a study of 64,000 people in Sweden who had suffered a heart attack or chest pains. An editorial in the journal concludes: "Obesity may carry benefit up to a certain degree."

Weighty issue: How stars shape up

Ian Botham

Height 1.88m

Weight Now 108kg, a bit trimmer in his heyday.

Widely regarded as one of cricket's finest ever all-rounders. His Test career, in which he amassed 5,200 runs, 383 wickets and plenty more newspaper headlines, spanned 15 years. Botham's propensity to carry a little extra bulk earned him the nickname "Beefy". His trademark slogs over cow corner for six carried plenty of meat.

Steve Thompson

Height 1.88m

Weight 118kg

England rugby's long-standing number two was often the team's number one in terms of weight. Thompson was a member of England's triumphant 2003 World Cup Rugby Union squad and is the country's most-capped hooker, with 73 appearances.

John Daly

Height 1.80m

Max weight 125kg

The American golfer won two majors: the US PGA in 1991 and The Open at St Andrews in 1995. Alcohol blighted his achievements as a golfer and earned him suspensions from the PGA Tour. Gastric band surgery has recently helped his successful weight-loss programme.

William Perry

Height 1.88m

Weight 152kg

American football player nicknamed "The Refrigerator" because of his size. His finest achievement was winning Superbowl XX with the Chicago Bears in 1986.

Shane Warne

Height 1.83m

Max weight 90kg

His 708 test wickets make him comfortably the second most prolific bowler ever to have graced the game. Warne's bamboozling leg spin was as confounding as his inability to lose weight. In 2003 he tested positive for a banned diuretic and served a year's suspension.

Laura Davies

Height 1.78m

Max weight 114kg

Britain's most famous female golfer, having won four majors and the Order of Merit on seven occasions – all in spite of her weight, which at times topped 18st.