True impact of intermittent fasting on body revealed in new 'gold standard' study

For many of us, losing weight can feel incredibly challenging, whether you've tried hitting the gym, cutting your calories right down or even had a crack at intermittent fasting.

The latter typically involves eating within a certain time window, such as between 11am and 7pm, but it can also include methods such as eating normally five days a week and majorly restricting calories for the other two.

Many people swear by intermittent fasting for keeping in good shape, including a number of celebrities like Jennifer Aniston, Terry Crews and Kourtney Kardashian-Barker — but the method is less effective for those who are overweight or obese, according to new research.

It comes after scientists from the Cochrane Institute, the 'gold standard' for evidence-based medicine, looked at 22 different studies involving 2,000 adults who are classed as obese or overweight, to investigate whether short-term intermittent fasting helped people lose weight over standard diet advice or no advice at all.

Jennifer Aniston has spoken publicly about intermittent fasting (Monica Schipper/Getty Images)

Interestingly, researchers found that over a 12 month period, intermittent fasters lost around 3 percent of their bodyweight, which is lower than the 5 perfect threshold doctors class as clinically meaningful.

It's important to note that those who are doing intermittent fasting aren't necessarily reducing their calories in doing so, which could be a key reason for not losing much weight.

According to Luis Garegnani, from the the Universidad Hospital Italiano de Buenos Aires, who led the review, the hype around fasting and its impact on weight loss and overall health is 'concerning.'

"Intermittent fasting may be a reasonable option for some people, but the current evidence doesn't justify the enthusiasm we see on social media," he said, as per the BBC.

However, they did highlight the fact that every individual is different and therefore their approach towards weight loss will be individual too.

Senior author of the study, Eva Madrid, added: "Doctors will need to take a case-by-case approach when advising an overweight adult on losing weight."

Many celebrities promote intermittent fasting (Getty Stock Images)

The researchers revealed they are 'moderately confident' on their findings, but admitted there are elements of the research they are less confident about.

To get a better understanding of intermittent fasting, more research is needed on the different kinds of fasting, as well as how it can impact men and women differently, and those different BMIs and race.

Summarising the research, Dr Baptiste Leurent, associate professor in medical statistics at University College London said it shows 'a clear indication that intermittent fasting offers little benefit.'

"This is yet another example of a misalignment between public perception and the scientific evidence," he added.

Fans of intermittent fasting have previously claimed a myriad of different health benefits, including claims it has 'special effects on metabolism,' but according to Professor Keith Frayn, emeritus professor of human metabolism at the University of Oxford, these claims are unfounded.

"This study shows that such claims can have little relevance," he said, explaining there are no 'quick fixes' for losing weight beyond reducing calories.