Can you really be FAT but FIT?
That’s what some experts think, but new research suggests the opposite. So what IS the truth?
OK, you’re a little bit on the plump side, but you’re doing your best, resisting that afternoon bar of chocolate, easing back on the midweek vino. More to the point, you feel fit — you walk a fair bit, and hit the treadmill a couple of times a week. your blood pressure is normal and your cholesterol levels are looking good.
you feel healthy, so what does it matter if you’re a bit, or even very, overweight?
And indeed there’s a theory that’s been gaining ground in recent years that being overweight isn’t necessarily the disaster for health we’ve been led to believe. In fact, so the thinking goes, it’s perfectly possible for some people to carry large amounts of fat, but still be healthy.
But the good news about fat may be over, for according to research published in the european Heart Journal last month, if you’re overweight you could still be putting your heart at risk — however apparently healthy you are.
The study, led by researchers at Imperial College London and the university of Cambridge, looked at the medical histories of 7,637 people who had contracted coronary heart disease.
What they found was that, while — unsurprisingly — being overweight or obese was a risk factor, this was still true even if someone had healthy blood pressure, blood sugar and cholesterol readings, collectively known as measures of metabolic health.
The researchers calculated that carrying extra weight, regardless of how healthy you might be otherwise, raises the risk of heart disease by 28 per cent compared with someone not carrying those surplus pounds.
‘Irrespective of metabolic health, overweight and obese people had higher risk [of coronary heart disease] than lean people,’ the authors concluded. This, they said, proved there was no such thing as healthy obesity.
on the face of it, this isn’t all that surprising. After all, we’re constantly reminded that obesity is a shortcut to ill health, increasing the risk of everything from diabetes and heart disease to cancer and dementia.
Bad news for the one in four British adults who are obese — that’s anyone with a body mass index or BMI of more than 30, so approximately 15½st for a man who is 6ft, or 13st 2lb for someone who is 5ft 5in.
And yet in recent years, fat has been linked to health benefits.
WHEN ‘OVERWEIGHT’ IS HEALTHY
IN 2005, for example, a study by the National Centre for Health Statistics looked at all deaths in the u.S. in a single year and found that being overweight (having a BMI between 25 and 29) ‘was not associated with excess mortality’ (i.e. dying from any causes), but being underweight (a BMI less than 18.5) was. A large-scale Danish study published in the International Journal of Stroke in 2015 also unearthed a puzzling truth with no obvious explanation: obese stroke patients were significantly less likely to suffer subsequent strokes than their lean counterparts and the stroke was far less likely to kill them.
WHY SCIENTISTS JUST CAN’T AGREE
LAST month’s research flies in the face of such evidence and a fierce debate is raging about its conclusions among scientists.
one man who scrutinised last month’s paper with disquiet was Norbert Stefan, chair of clinical and experimental diabetology at the university of Tübingen in Germany. Professor Stefan was among the first to identify the notion of metabolically healthy obesity — being healthy and fat — in a paper published in the Archives of Internal Medicine.
His team found that, contrary to expectation, in a proportion of obese patients, obesity was not accompanied by insulin resistance or a build-up of fats in the arteries.
The key, he believes, is that the build-up of unseen fat in the liver and other organs may be more important than ‘visceral’, or deepseated belly fat, fat that’s wrapped around the organs.
Some obese and overweight people will have both kinds of fat, but some, while overweight, won’t have this unseen fat in the organs, the more dangerous kind, or so the theory goes.
Professor Stefan says the results of the new paper show a major difference in the risk of heart disease for obese people, whom the researchers defined as ‘healthy’ and those they classed as ‘unhealthy’.
‘The risk for the metabolically healthy obese is given as 28 per cent higher, but the risk for the metabolically unhealthy obese is 254 per cent — nearly ten times higher,’ he says.
‘If there was no such thing as metabolically healthy obesity, then the risk ratios should be very similar.’
But Dr Ioanna Tzoulaki, an epidemiologist from Imperial’s School of Public Health and one of the paper’s authors, disagrees.
‘The fact the healthy obese are more at risk compared with lean, healthy people shows there is no healthy obesity,’ she says.
‘These healthy obese individuals are on the road to becoming metabolically unhealthy.’
The problem isn’t the fat itself, says Dr Tzoulaki, but what can accompany it — increased blood pressure and raised blood sugar (glucose) levels.
‘If anything, our study shows people with excess weight who might be classed as “healthy” haven’t yet developed an unhealthy metabolic profile,’ she adds. ‘ That comes later in the timeline, then they have an event, such as a heart attack.’
The paper monitored the participants for an average of 12 years, so what will happen to them in the long run remains unknown.
Meanwhile, recent research by a team from the Institute of Applied Health research in Birmingham analysed the anonymised GP records of 3.5 million patients across the uK, from 1995 to 2015.
They monitored patients who had a BMI of 30 or more, but who also had normal blood pressure and cholesterol and no diabetes — to see how many suffered cardiovascular conditions.
Compared with healthy people of normal weight, the ‘ healthy obese’ had a 49 per cent increased risk of coronary heart disease, a 7 per cent higher risk of stroke — and a whopping 96 per cent increased risk of heart failure.
‘The idea people can be obese but not be at risk for developing cardiovascular disease is a myth,’ says Dr rishi Caleyachetty, an epidemiologist at the university of Birmingham.
SO WHAT COUNTS AS ‘FAT BUT FIT’?
PArT of the confusion is that different studies use different measures of what counts as being fat but ‘healthy’. The definition of ‘fat but fit’ depends on how many risk factors a patient has for the condition known as metabolic syndrome, such as insulin resistance, glucose intolerance and high levels of ‘bad’ cholesterol, and low levels of the ‘good’ kind.
on this basis, Professor Stefan says the latest research is flawed. ‘We suggest someone who is obese is unhealthy if they have more than one of these factors,’ he says. ‘But in the recent paper they allow an individual to have two.’
The consequence of this, he says, is that a far greater percentage of the obese people defined as ‘ healthy’ in the new research inevitably ended up having heart problems — because by his stricter definition they were never ‘healthy’ in the first place.
Dr Tzoulaki dismisses this. ‘We chose a definition of metabolic syndrome as suggested by international guidelines,’ she says.
So what does this mean for you? If you’re battling with your weight, focusing on being ‘fat but fit’ is more helpful than simply worrying about the number on the scale, says Professor Stefan — a diabetes specialist who daily sees patients trying to lose weight.
‘I tell them to start doing some exercise, change your diet and try to lose 5 to 8 per cent of bodyweight,’ he says. ‘In three months, they come back frustrated because they have been walking every day and yet their BMI is the same or even higher.’
BMI can’t differentiate between fat and muscle weight, he says, ‘and a person of 150kg (23st 8lb) who is walking two hours a day gains a lot of muscle mass’.
But, while their BMI won’t have changed, blood pressure, cholesterol and triglycerides (blood fats symptomatic of a high- calorie diet) will.
‘It doesn’t matter what size you are, you can do something to improve your health,’ agrees Duane Mellor, a spokesman for the British Dietetic Association.
If you are a bit heavier, he says: ‘The most helpful message is be more active and eat better — reduce portion sizes and eat less food that’s high in fat and sugar.’
And ditch the scales: ‘Don’t worry about the weight — we don’t have much evidence that weight loss on its own is the best thing,’ he adds.