In a 2011 study published in the British scientific journal Nature, it was found that eliminating these senescent cells “forestalled many of the ravages of age”.

Experiments on mice since this initial discovery have confirmed that senescent cells accumulate in ageing organs, and eliminating them can alleviate, or even prevent, certain illnesses.

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Glucose that animals get from food fuels the trillions of cells in the body, including zombie cells. Cutting off the supply of glucose to these damaged cells can prevent them secreting harmful proteins and molecules. This in turn slows the process of ageing and staves off diseases such as cancer, dementia and arthritis.

But research to date has only been conducted on mice, so the impact of fasting on human ageing is still relatively unknown.

“We know that if we give most animals less food than they would normally eat they’ll live much, much longer. The drive behind this type of research is to make animals be healthier for longer, because we know age is the primary risk factor for a whole host of diseases,” says Colin Selman, a professor of biogerontology at the University of Glasgow, in Scotland.

But fasting completely for five days may not be the most effective way to get positive results.

Studies in mice have found that reducing their food intake, or providing food within a compressed amount of time, also has benefits.

“There are quite a lot of studies where you feed mice every second day, or you restrict their access to food over a 24-hour period. And there is evidence from some studies that if you eat the same amount of food as you would normally, but compress it into a shorter period within that day, that also has beneficial effects,” Selman says.

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But the impact on people, and research examining the correlation between fasting and stopping the spread of senescence, is still very much in its infancy.

“In general you would predict from the evidence that reducing the amount of food has beneficial effects on health. But precisely how that’s achieved and whether it would be through the removal of these zombie cells is difficult to ascertain because fasting has so many effects,” Selman says.

Despite their zombie nickname, senescent cells do have a positive role to play in the body. The process of senescence stops the spread of damaged mutated cells.

Research from the University of California, San Francisco, in the United States, has also demonstrated that senescent cells help to heal damaged tissue.

That study, published in American scientific journal Science, found some zombie cells were embedded in young tissue and promoted normal repair from damage. They also found that senescent cells exist in young and healthy tissues from birth.

When it comes to fasting, which foods to cut out and how long to fast for is still up for debate.

These included the consumption of only water for 48 hours at a time; or existing on a low-protein, low-sugar, high-fat, low-calorie diet for two to five days between longer periods on a standard diet.

Scientists are now trying to develop drugs which can deliver the same benefits that dietary restrictions do.

“If you think about interventions to improve health, like reducing food intake and [doing more] exercise, it’s not an easy thing to motivate yourself [to do]. But if you can get some sort of drug that mimicked the beneficial effects while you’re still able to have your cake, that’s what people would want,” Selman says.

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“All of these things influence the rate at which you age,” Bellatuono says.

She adds that, at this point, “we don’t know how much fasting we really have to do, and to what degree, before it becomes detrimental”.