Fasting for three days can regenerate entire immune system, study finds

By Sarah Knapton, Science Correspondent in The Telegraph

Fasting for as little as three days can regenerate the entire immune system, even in the elderly, scientists have found in a breakthrough described as "remarkable".

Although fasting diets have been criticised by nutritionists for being unhealthy, new research suggests starving the body kick-starts stem cells into producing new white blood cells, which fight off infection.

Scientists at the University of Southern California say the discovery could be particularly beneficial for people suffering from damaged immune systems, such as cancer patients on chemotherapy.

It could also help the elderly whose immune system becomes less effective as they age, making it harder for them to fight off even common diseases.

The researchers say fasting "flips a regenerative switch" which prompts stem cells to create brand new white blood cells, essentially regenerating the entire immune system.

"It gives the 'OK' for stem cells to go ahead and begin proliferating and rebuild the entire system," said Prof Valter Longo, Professor of Gerontology and the Biological Sciences at the University of California.

"And the good news is that the body got rid of the parts of the system that might be damaged or old, the inefficient parts, during the fasting.

“Now, if you start with a system heavily damaged by chemotherapy or ageing, fasting cycles can generate, literally, a new immune system."

Prolonged fasting forces the body to use stores of glucose and fat but also breaks down a significant portion of white blood cells.

During each cycle of fasting, this depletion of white blood cells induces changes that trigger stem cell-based regeneration of new immune system cells.

In trials humans were asked to regularly fast for between two and four days over a six-month period.

Scientists found that prolonged fasting also reduced the enzyme PKA, which is linked to ageing and a hormone which increases cancer risk and tumour growth.

"We could not predict that prolonged fasting would have such a remarkable effect in promoting stem cell-based regeneration of the hematopoietic system," added Prof Longo.

"When you starve, the system tries to save energy, and one of the things it can do to save energy is to recycle a lot of the immune cells that are not needed, especially those that may be damaged," Dr Longo said.

"What we started noticing in both our human work and animal work is that the white blood cell count goes down with prolonged fasting. Then when you re-feed, the blood cells come back. So we started thinking, well, where does it come from?"

Fasting for 72 hours also protected cancer patients against the toxic impact of chemotherapy.

"While chemotherapy saves lives, it causes significant collateral damage to the immune system. The results of this study suggest that fasting may mitigate some of the harmful effects of chemotherapy," said co-author Tanya Dorff, assistant professor of clinical medicine at the USC Norris Comprehensive Cancer Center and Hospital.

"More clinical studies are needed, and any such dietary intervention should be undertaken only under the guidance of a physician.”

"We are investigating the possibility that these effects are applicable to many different systems and organs, not just the immune system," added Prof Longo.

However, some British experts were sceptical of the research.

Dr Graham Rook, emeritus professor of immunology at University College London, said the study sounded "improbable".

Chris Mason, Professor of Regenerative Medicine at UCL, said: “There is some interesting data here. It sees that fasting reduces the number and size of cells and then re-feeding at 72 hours saw a rebound.

“That could be potentially useful because that is not such a long time that it would be terribly harmful to someone with cancer.

“But I think the most sensible way forward would be to synthesize this effect with drugs. I am not sure fasting is the best idea. People are better eating on a regular basis.”

Dr Longo added: “There is no evidence at all that fasting would be dangerous while there is strong evidence that it is beneficial.

“I have received emails from hundreds of cancer patients who have combined chemo with fasting, many with the assistance of the oncologists.

“Thus far the great majority have reported doing very well and only a few have reported some side effects including fainting and a temporary increase in liver markers. Clearly we need to finish the clinical trials, but it looks very promising.”

A Diet for those who love to eat and wish to lose weight

The 5:2 diet – feasts for fast days

With its flexible approach and simple rules, the 5:2 diet has become the calorie-control plan for people who like to eat

• 
• • Felicity Cloake
  • The Guardian, Sunday 5 May 2013 19.30 BST

The fasting diet, otherwise known as the 5:2, restricts calories for two days a week. Photograph: Felicity Cloake

For the first time since university I am on a diet. Somehow, I've become a calorie-counter, someone who weighs out porridge oats and drinks herbal tea. In other words, the kind of person I've always pitied.

1. Perfect Host: 162 easy recipes for feeding people and having fun
2. by Felicity Cloake
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1. Tell us what you think: Star-rate and review this book

The thing is, I'm actually quite enjoying it – enjoying being a relative term, of course. In an ideal world, I'd boast the kind of robust metabolism that laughs in the face of cooking six bakewell tarts an afternoon, but I don't. And since I started my Perfect recipe column a couple of years ago, I've noticed the pounds slowly creeping on. There's a lot to love about my job, but it does make it almost impossible to eat healthily.

The fasting diet, otherwise known as the 5:2 because of the format – five days of normal eating a week and two in which you restrict your calories (500kcal for women, 600kcal for men) – seemed to offer a glimmer of hope for my hips. It's basically the diet for people who like food. Everyone from Hugh Fearnley-Whittingstallto wine writer Fiona Beckett has been boring on about fast days, and if they could do it, well, so could I.

So far, I've managed two months. As someone who's never made a habit of weighing themselves, I can only tell you that I think I've lost about 10lb since I started, which includes a two-week period over Easter where I gave myself a bit of a break, but only put back on 1lb.

The odd thing was, after Easter I was impatient to get going again. The 5:2 already feels like a long-term project. It's not difficult to stick to either. After all, if you really want a biscuit, you can always have one tomorrow – a thought I find extremely cheering.

Many people I've spoken to seem to avoid cooking at all on a fast day, reasoning perhaps that it simply puts temptation in their way. Indeed, in her book, the Fast Diet, co-authored with Dr Michael Mosley, whose 2012 BBC Horizon programme on fasting kickstarted interest in the idea, Mimi Spencer advises preparing food in advance, and keeping it simple, "aiming for fast-day flavour without effort".

I couldn't disagree more. For me, the challenge of devising satisfying recipes that fit within the daily 500-kcal limit has kept fast days interesting, and frankly, if you're only going to be eating two small meals a day, heating them up in the microwave makes things even more depressing. Here are a few tips I've found useful so far, and three of my favourite fast-day recipes …

• Low-calorie cooking is all about strong flavours: pungent spices, zesty lemon juice and salty soy sauce will all help to distract your attention from the missing calories, as will lots of garlic and big handfuls of fresh herbs.

• Don't be too hard on yourself. Usually I sniffily avoid artificial sweeteners, but a cold glass of slimline tonic with a slice of lime and plenty of ice goes down a treat when everyone else is glugging wine. I've even been known to indulge in a low-calorie pot of jelly when I'm feeling particularly wild.

• Carbs are rarely worth the calories. A paltry 50g of brown rice takes up over a third of your daily calorie count. Save them for tomorrow and fill up on vegetables and berries instead.

• Pickles such as gherkins (14kcal per 100g) and miso soups (20-30kcal a cup) are your friends for snacks.

• Drink lots. Sparkling water, evil diet drinks and weird and wonderful teas will keep you occupied mid-afternoon.

• Embrace your inner nerd and invest in a set of electronic scales and a calorie-counting book or app, or you'll find it impossible to measure your intake accurately.

Navratri and the lessons of fasting for atheists

Spiritual disciplines can teach us much about food discipline – I found my 10-day fast extremely rewarding



Julian Baggini

guardian.co.uk, Monday 22 October 2012 15.34 BST



It might seem odd but I, a convinced atheist, have recently completed a 10-day fast based on the Hindu festival of Navratri, which is being celebrated this week. Fasting is refraining from eating at all, or more usually certain proscribed foods.





These days, if we limit what we eat, it is almost certainly because we are trying to lose weight, detox or realise some kind of health benefit. The idea that we might seek to forgo certain foods for moral improvement seems bizarrely anachronistic. The penance of Catholic Lent and Friday fasting make as little sense to most of us as the once common idea that food should be avoided after a death for fear that food around the deceased would be impure.





But there are some real lessons we can learn from spiritual disciplines around food. For the Benedictine former abbot Christopher Jamison, only eating certain things at certain times is a way of countering our tendency to slavishly follow our desires. "It's a way of exercising choice very knowingly," he told me, "and at the same time a way of exercising discipline around food." Similarly, the Buddhist abbot Ajahn Sucitto says that too often eating becomes just one of those "compulsive activities which on a functional level are not necessary. We do it just because of a psychological habit."





For reasons like this, I thought fasting was worth a try and Navratri – literally meaning nine nights in Sanskrit – looked like a good model. It heralds the start of autumn, and is dedicated to Shakti, the deity responsible for creation. My rules were that I would eat three meals a day, with no snacking in between of any kind. I would forgo meat, seafood and dairy products and would not drink alcohol or eat sweets or cakes. I would strive to eat each meal mindfully and thankfully and on the last evening would have some kind of feast, a celebration of the pleasure and variety of good food rather than an excessive gorging. The idea can be summed up as countering the bad A of automaticity with the three good As of right appreciation, right autonomy and right action.





I found the 10 days extremely rewarding. It wasn't meant to be a trial, and when I did feel hungry I reminded myself that such feelings pass, and unless we're really starving, we can always choose to wait until our next meal.





I'm not the only atheist learning from religious fasting. The philosopher James Garvey, my successor as editor of the Philosophers' Magazine, has also followed a version of the Ramadan fast several times. "There is some sort of discovery of a part of yourself involved, or maybe a discovery associated with the human experience," he told me, "a feeling of being in control of your appetites for once. I can see why so many religions do it."





I've become quietly evangelical about it. Some people have no trouble controlling their appetites or just don't care much for food. But I suspect most of us eat too thoughtlessly too often. I plan to repeat my fast twice a year, around the spring and autumnal equinoxes. The next one starts on 14 March. I'd be happy for you to join me.