Following a ‘fashionable’ fast for just one week can damage the heart, research suggested in February 2018.
Obese people who suddenly lower their calorie intake to just 600-to-800 units a day, experience heart-fat level increases of 44 per cent, a trial found today.
Despite such dieters on average losing six per cent of their total body fat after just seven days, this fat is released into their bloodstream and absorbed by their hearts, the researchers explained.
Although this excess heart fat balances out by week eight of dieting, for people with heart problems, it could leave them breathless and with an irregular beat, the scientists add.
Study author Dr Jennifer Rayner from the University of Oxford, said: ‘Otherwise healthy people may not notice the change in heart function in the early stages.
‘But caution is needed in people with heart disease.’
Heart disease, which is linked to obesity, affects more than 1.6 million men and one million women in the UK.
Dr Rayner added:’The heart muscle prefers to choose between fat or sugar as fuel and being swamped by fat worsens its function.
‘People with a cardiac problem could well experience more symptoms at this early time point, so the diet should be supervised.
‘Otherwise healthy people may not notice the change in heart function in the early stage.’
The researchers analysed 21 obese volunteers with an average age of 52 and a BMI of 37kg/metre squared.
The study’s participants ate a very low-calorie diet every day for eight weeks.
MRI scans were taken at the start and end of the investigation, as well as after week one.