Tiny weight gain raises stroke risk by making your heart fat
BEING even slightly overweight makes your heart larger and heavier – raising the risk of suffering a heart attack or stroke, research shows.
The first study of its kind has found that putting on weight can add up to 8g to the heart – and increase its volume by almost 5 per cent.
A bigger, heavier heart raises the risk of conditions from an irregular heartbeat to a heart attack.
researchers at the University of Oxford and Queen Mary University of London examined MrI scans for 4,561 people. They found that even a slight rise in weight made the heart substantially heavier.
It matters because a larger heart stretches its upper chambers, disrupting the electrical signal needed to keep it beating regularly.
While people have long known they risk heart disease from overeating because it hikes their cholesterol and blood pressure, this is the first evidence that becoming overweight changes the structure of the heart itself.
Professor Steffen Petersen, lead author at Queen Mary, said: ‘We all know that our lifestyle has a big impact on our heart health – particularly if we’re overweight or obese.
‘But researchers haven’t fully understood how exactly the two things are linked.’
The results suggest that the obesity crisis could be contributing to soaring rates of Britons suffering atrial fibrillation – or irregular heartbeat.
This raises people’s risk of stroke because the atria, which are the two upper chambers of the four chambers in the heart, fail to pump properly.
Professor Petersen said: ‘The increase in the left atrium’s size stretches it so that it does not play its part in conducting an electrical impulse from the sinus node, the pacemaker of the heart, to the node which causes the heart to beat.’
The researchers looked at lifestyle factors including blood pressure, smoking, drinking, exercise, cholesterol, diabetes and weight, measured using body mass index ( BMI) – weight in kilograms divided by height in metres squared.
Body weight had the biggest consistent impact on the heart’s structure, according to the study published in the journal PLOS ONE.
A BMI increase of 4.3 increased the weight of the left side of the heart by 8.3 per cent.
This weight bracket would include people who go from a healthy BMI of 25 to one of 29.3, which is in the overweight category and close to the obesity threshold of 30.
Men in this group would add about 8g to their heart, which weighs an average of 64 to 141g. Women, whose hearts weigh up to 93g on average, would see theirs increase by about 6g.
The volume increase was estimated at around 8ml for men and 6.5ml for women.
The study was funded by the British Heart Foundation, whose medical director Sir Nilesh Samani said: ‘ This research shows the silent impact of being overweight and having high blood pressure on the structure and function of the heart. The important message is that these are things we have the power to change before they result in irreversible heart damage.’
It is estimated more than a quarter of the risk of having a heart attack comes from avoidable lifestyle factors looked at in the study.
Professor Francesco Cappuccio, professor of cardiovascular medicine and epidemiology at the University of Warwick and president of the British and Irish Hypertension Society, said: ‘This is an important study that reinforces the concept that the prevention and control of hypertension, high cholesterol and diabetes remain the most important modifiable factors for the prevention of heart damage.’
‘Irreversible damage’