My summer of fasting

January 19, 2018 by
Life   No Comments Yet

TS Eliot was wrong. September – actually – is the cruellest month. All that summer bonhomie dissipated the instant you try to do up your winter jeans. But not this year, not for me. Because while you were all off on holiday having a good time, I was undertaking a trial of Prolon, the new fasting-mimicking diet (FMD) programme, which has been designed to kickstart the body at its cellular level, reduce the chance of chronic disease and potentially improve longevity. On this type of fast – a scientifically designed pre-packed micro diet consisting mostly of very low calories soups – you can lose weight, especially from the abdomen, and see levels of cholesterol and other risk factors for disease fall.

Finding a way to deal with obesity has never been more important. According to a new report in The Lancet from the ongoing Global Burden of Disease study, 72 per cent of deaths are from non-communicable diseases for which

obesity and diet are among the risk factors, with ischaemic heart disease as the leading cause worldwide of early deaths, including in the UK. The study reveals that poor diet is a factor in one in five deaths around the world.

And recommendations from the National Institute of Health and Care Excellence (Nice) could soon see every single person aged 40 and over offered an NHS diabetes check, with potentially five million Britons at risk of type 2 diabetes ordered to go on strict diets by GPs as a result.



Health benefits of fasting

Which is where Prolon could come in. This fasting regime is the brainchild of bio-gerontologist and cell biologist Prof Valter Longo, Director of the Longevity Institute at the University of Southern California (USC) who is fascinated by the way the body behaves when calories are restricted through periodic fasting (PF) – fasting which lasts from more than two days at a time.

“Almost every chronic disease is age-related,” Prof Longo says. “From Alzheimer’s to Parkinson’s, cancer, type 2 diabetes and cardiovascular disease (CVD). In our research, we are seeing a tremendous effect on these diseases: mice who fast live longer and with much less disease.” His most recent study showed that a FMD diet could restore the production of insulin and balance blood sugar levels in mice with both type 2 and type 1 diabetes.

In research, some of these benefits are beginning to be revealed in humans too. Most recently a USC study found that markers most associate with chronic diseases such as type 2 diabetes and CVD – body mass index (BMI), blood pressure, fasting glucose, IGF-1 (insulin-like growth factor), triglycerides, total and low-density lipoprotein cholesterol, and C-reactive protein (which increases in response to inflammation levels) – fell in subjects who were placed on the FMD for five consecutive days per month for three months.

Although Prof Longo is keen to stress that we need more and larger studies in humans before making definitive claims, it would be difficult to argue that something is not going on.

So how could PF work? “The way this type of fasting improves our health is multi-fold,” he explains. “When our calorie intake is restricted it stimulates and speeds up autophagy – the orderly breakdown of old cells in the body which might otherwise begin to degenerate and cause disease. By helping us to slough off these old toxic cells, PF promotes the growth of new healthy stem cells instead.

“We think fasting can cure a damaged cell and make a normal cell healthier.”

In addition, periodic fasting seems to help shift visceral fat – the layer under our muscles which wraps around our organs (and which seems to come as standard in middle age). This is the dangerous type of fat as it inhibits crucial organs like the liver from working efficiently. Yet as it collects independently to subcutaneous fat – the kind which gathers under the skin – you can look in good shape but be storing up health problems for the future.

It is possible, explains the professor, that what PF is doing is giving the body a break from constantly stock-piling new calories, exhausting itself in the process, so that it can work efficiently again.

One particularly promising area of study is in cancer treatment. His studies indicate that fasting could make cancer cells more receptive to chemotherapy while protecting other healthy tissue.

While Prof Longo isn’t suggesting fasting could be some kind of alternative cure, he points out that “medicine doesn’t take you back to when you were healthy – it merely blocks the problem. Fasting rejuvenates the system. If there is a problem with the liver, for example, PF can shrink the liver, get rid of the damaged cells and then allow the liver to expand again.”

So do the tens of thousands who practise the 5:2 diet – five days normal eating, two days fasting, as recommend by Dr Michael Mosley – also get these benefits? “That’s not really fasting,” says Prof Longo, gently. “It takes 30-40 hours to deplete the liver of glycogen before the body has to start burning abdominal fat properly.”

Getting down to the diet

With all this in mind, I went to be weighed and measured at nutritionist Kim Pearson’s Harley Street practice in June and to begin the regime.  Having tried a prototype of the Longo diet two years ago, I knew what to expect: tiny portions, headaches and a gnawing feeling in my stomach that could have been hunger but would also probably be despair.

That time I had approached the diet merely as a way to shed some pounds fast – and I did: half a stone had melted off. But time, and biscuits, had seen the weight creep back on and I was horrified to see the scales had snuck back up and beyond my previous weight.  This time, my body fat was almost 40 per cent and my BMI was 27.7 (the normal range is 18-25).

This summer, my mission wasn’t just to lose weight but to improve radically my blood markers. My blood sugar was in the normal range, but my cholesterol was creeping up. What could 15 days of fasting spread out over a summer do?

Feeling motivated, the first five days were not terrible. The diet allows you 1100 calories on day one, and then 800 calories on each subsequent day. A nut bar for breakfast is followed by two more packet soups at meal times, with occasional sachets of olives to keep you going.  The idea is not to starve, but to trick the body into thinking it does not need to go into survival mode. Just to work a bit harder with the fat already on board.  Yes, I got stonking headaches on day two and three, but I slept incredibly well too.

The next three weeks of “normal” eating seemed to go faster than the five days of fasting. But, as I kept telling myself, anyone can do anything for five days. Even eat kale crackers.

By the next rest period, I was feeling so much more comfortable in my clothes, that I was becoming more mindful of my every-day diet. Pearson, who is offering the plan to her clients, says that in between fasts – and afterwards, she encourages a Mediterranean diet. “Stick to a predominantly plant-based dairy-free diet,” she says, “moderate amounts of protein, moderate carbs coming mostly from veg and pulses rather than processed grains, but rich in nuts, seeds and olive oil, plus the occasional square of very dark chocolate.”

Pearson has only been offering Prolon – which costs about £225 per fast – for a few months but reports her clients are thrilled with the results. “I’ve done it myself,” she says. “Of course, you feel hungry, but the great thing is it could benefit so many different people.”

I found the last five days were toughest but I didn’t crack. It was difficult to concentrate on days four and five. But was I occasionally grumpy or short-tempered? Well, my family swore blind that I was my usual cheery self. But then perhaps they didn’t want to provoke me, further.

So what was the final result? I can reveal it was very gratifying: my cholesterol was back in the normal range, my inflammatory marker had been reduced by two-thirds.

And the weight loss was stunning: 11lbs off, including 7.5lbs of pure fat. My BMI was down to 26, and my body fat was now 37 per cent.

Particularly pleasing was the consistency: pounds that came off during the first fast stayed off even when I ate normally. Another benefit was that my appetite shrunk and stayed that way. Six weeks later, the weight has not crept back on and I am feeling more motivated to eat in a mindful way.

Prof Longo is convinced that we would all only need to do his fast three times a year to stay healthy and on top of our weight. Just think of that: 15 days of annual denial in exchange for reducing your risk of chronic illness or early death.  That’s the deal of a lifetime.




Body fat

Visceral fat



C-reative protein


11.12lb (75.4kg)

39.7 per cent

107.5kg/cm squared





11.1lb (70.7kg)

37 per cent

96.8 kg/cm squared





This article first appeared in the Daily Telegraph 2017.




Six months later, my weight has stayed exactly the same as at the end of the diet. I achieved this stability by cutting out dairy and eggs at Kim Pearson’s suggestion but not restricting my diet in any other way.


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