The idea that people can be fat but medically fit is a myth, say experts speaking in Portugal.
Their early study, as yet unpublished, involved looking at the GP records of 3.5 million people in the UK.
They say people who were obese but who had no initial signs of heart disease, diabetes or high cholesterol were not protected from ill health in later life, belying previous research.
A summary of their study was discussed at the European Congress on Obesity.
The term “fat but fit” refers to the alluring assumption that if people are obese but all their other metabolic factors such as blood pressure and blood sugar are within recommended restrictions then the extra weight will not be harmful.
In this study, researchers at the University of Birmingham analysed data of millions of British patients between 1995 and 2015 to see if this claim comprised true.
They tracked people who were obese at the start of the study( defined as people with a body mass index of 30 or more) who had no evidence of heart disease, high blood pressure, high cholesterol or diabetes at this level.
They found these people who were obese but “metabolically healthy” are currently under higher hazard of developing heart disease, strokes and heart failure than people of normal weight.
Is the ‘fat but fit’ assumption well and truly busted?
Dr Mike Knapton, from the British Heart Foundation, told: “It’s not often that research on this scale and magnitude is able to clarify an age-old myth.
“These findings should be taken extremely seriously and I’d urge healthcare professionals to take heed.”
He added: “Previously we used to think that being overweight led to an increase in heart attack and stroke because it elevated your blood pressure or cholesterol.
“What was new from the results of the study for me is that it showed that people who were overweight or obese are currently under high risk of heart disease even though they may have been healthy in every other respect.
“Just being overweight puts you at high risk of heart attack and stroke.”
But the study has not appeared in a scientific journal and, as such, it will not have gone through a number of checks by other academics to judge whether it is scientifically sound.
This makes it difficult for scientists to see how clear-cut the conclusions are or gauge how big any increased risks of ill-health might be.
What should people do?
According to the British Heart Foundation, the normal heart health advice utilizes – not smoking, feeing a balanced diet, exercising regularly and limiting alcohol intake – can all help keep people healthy.
Dr Knapton added: “This is not about laying the blame at men though.
“This is a wake-up call for planners, local councillors, food both manufacturers and the government to make sure we can make healthy selections more easily.”
Dr Rishi Caleyachetty from the University of Birmingham, added: “The priority of health professionals should be to promote and facilitate weight loss among obese persons, regardless of the existence or absence of metabolic abnormalities.”
He added: “At the population level, so-called metabolically healthy obesity is not a harmless condition.”
Does everyone agree?
Other studies propose it might just is the possibility to be fat and has every right to genes, for example, to remain fit.
For example research published in 2012 appears to suggests it is possible for people to buck the trend and be fat and healthy if they have no metabolic diseases.
Published in the European Heart Journal, researchers propose people who are obese yet physically healthy are at no greater hazard of heart disease or cancer than people of normal weight.
Fitness and fatness: tricky things to measure?
But other experts point out that the route scientists measure fatness and fitness builds this a tricky area to survey and could construct some of the more tantalising makes invalid.
Tom Sanders, emeritus prof of nutrition and dietetics, King’s College London, says a major weakness of the Birmingham study is that it applies definite cut-offs to decide when someone has high blood pressure or high cholesterol for example.
Instead, he argues that it is too simple and not accurate to use such definite values to decide whether someone is healthy.
And other studies have suggested that is not always the amount of fat that are important but where where the extravagance fat is carried on the body that can affect fitness and health.
For example, weight towards the middle may be more damaging than weight distributed evenly around the body.
Overall, experts say it is important to not only focus on what the hell are you see in the reflect or on the scale of assessments – exercise and healthy feeing can help boost wellness , no matter how much a person weighs.