If feeling hungry for three days at a time sounds like your idea of hell, diet biohacking is not the diet for you.

Biohacking involves living differently to change how your body works, and Silicon Valley CEOs just can’t get enough of it.

However, by embarking on strict fasting regimens, that in some cases leave dieters consuming nothing but water for 36 hours, nutritional experts warn that these food-deprived tech execs could be exacerbating pre-existing conditions and, in some cases, masking an underlying eating disorder.

There are endless studies to show the benefits that intermittent fasting diets – such as the popular 5:2 - can have on the body, from weight loss to tackling diabetes to lowering the risk of heart disease. It's also been reported to boost brain power.

Phil Libin, the former CEO of Evernote and current CEO of AI Studio All Turtles told The Guardian that regular periods of fasting have made him “a better CEO,” citing it as one of the most important things he’s ever done in his lifetime.

"Most people think that my regimen is crazy and that it is impossible”, Geoffrey Woo CEO and co-founder, of Nootrobox supplements, told The Independent earlier this year when he conducted a week-long fast at his company with 100 members of WeFast, a community he launched for those who regularly practise intermittent fasting.

He now fasts for 36 hours every week and embarks upon three-day fasts four times a year.

Fasting reached peak popularity in 2014, when the 5:2 racked up a substantial celebrity following, which included the likes of Miranda Kerr and Jennifer Anniston. Then came the eight hour diet, which limited the hours of eating to a restricted time period.

However, it wasn’t until neuroscientist Mark Mattson gave a TED talk entitled “why fasting bolsters brain power” that the tech wizards of Silicon Valley really started paying attention to fasting as a means of biohacking.

Mattson explained that our brains respond to the challenge of fasting by activating adaptive stress response pathways that help the brain cope with anxiety and reduce the risk of disease.

He argued that fasting also increases the production of proteins in the brain called neurotropic factors, which promote the growth of and synapses of neurons. This increases the number of mitochondria neurons in the brain, which explains the surge in energy and learning and memory ability that many intermittent fasters claim to experience.

He likened the brain's response to fasting to its reaction to exercise and explained that we could all benefit from an increase in productivity on days that we fast.

He also explained that our generic "three meals a day plus snacks" routine benefits food companies more than it does members of the public.

“The food industry: are they going to make money from me skipping breakfast like I did today?” he told the audience at John Hopkins University.

However, nutrition experts disagree, explaining that fasting can be extremely detrimental to our health in the long term.

“Our bodies need nutrients to function,” Jo Travers told The Independent.

“Practically every process that happens in the body needs a vitamin, mineral or amino acid, and if you don’t eat for long periods then this can affect how the processes work. If you don’t eat protein (the main ingredients of hormones, enzymes, neurotransmitters and important for cell structure), your body will break down muscle in order to recycle the components. So muscle breakdown accounts for quite a bit of the weight loss in fasting diets, rather than fat,” the registered dietician and Low Fat Diet author explained.

She added that this can have a reverse effect on weight loss in the long term by actually increasing our body fat percentage.

Leading Harley Street nutritionist Rhiannon Lambert agrees, citing fasting as particularly harmful for those with pre-existing mental health conditions.