Scientists from Oxford University in the UK conducted a study of 21 obese volunteers with an average BMI of 37. The study placed the volunteers on a calorie-restricted diet, designed to mimic common popular diets being marketed to mass populations. Each participant was reduced to 600-800 calories per day (the average recommended daily intake for a healthy male is 2500 calories per day).
"Crash diets, also called meal replacement programmes, have become increasingly fashionable in the past few years," said lead author Dr Jennifer Rayne.
Through MRI investigation, the scientists measured organ fat surrounding the abs, liver, and the heart at the one week and eight-week marks.
Unsurprisingly, at the one week mark, total body fat had dropped among the participants by an average of 6 per cent, with liver fat down a whopping 42 per cent. However, alarm bells were raised when analysing the fat content in the heart, with results showing an average rise in fat surrounding the heart by 44 per cent, after only one week.
Offering an explanation for these drastic findings, Dr Rayne says the increased pressure placed on the heart, a subsequent reduction in functioning, is caused by lost fat traveling through the blood. "The sudden drop in calories causes fat to be released from different parts of the body into the blood and be taken up by the heart muscle," she continued. "The heart muscle prefers to choose between fat or sugar as fuel and being swamped by fat worsens its function.
Despite the initial spike in heart fat after the first week of crash dieting, by the end of the 8-week trial, heart fat, body fat, and cholesterol were all further improved, ultimately leaving participants in better condition than before the trial commenced.
However, these specific findings suggest diving right into severe calorie poses severe risk to overweight populations as their bodies adjust to this change. A more sustainable and gradual approach is recommended off the back of these findings:
“After the acute period in which the body is adjusting to dramatic calorie restriction, the fat content and function of the heart improved. If you have heart problems, you need to check with your doctor before embarking on a very low calorie diet or fasting. People with a cardiac problem could well experience more symptoms at this early time point, so the diet should be supervised."
This article originally appeared on Men's Health.