Can calorie deprivation be good for you?
To anyone keeping even a precursory eye on pop culture, low-calorie diets are nothing new, and in a world where headlines on the obesity epidemic are rife, calorie curbing can seem like simple common sense.
Yet a growing community of health disciples across the world are pinning their hopes on an extreme strain of calorie restriction, in the belief that five miniscule meals a day will significantly extend their lifespan.
Known commonly as the CR (calorie restriction) diet, its followers are not so much motivated by vanity or the attainment of a bodily ideal. This is not an eating plan for those merely concerned with shedding pounds and it is not inspired by celebrities wanting to look red-carpet ready.
Rather, the 'CRonies'' dedication to nutrition and optimum health is almost slavish.
First and foremost, the CR diet is described as an anti-ageing diet. And, according to a recent report in 'Psychology Today', around 80pc of CR practitioners are men.
CR followers reduce their calorie intake to an extent where they are taking in up to 30pc fewer calories than an average Western diet. Essentially, the aim is to eat as many nutrients while taking in as small an amount of energy as is possible.
And to those more used to a hearty Western diet, a typical CR meal plan could make for somewhat baffling reading.
A typical meal plan might be: a breakfast of 100g of cottage cheese with a handful of nuts and strawberries and a low-calorie cereal bar; a lunch of skinless chicken breast with half a cup of broccoli and an orange; and a dinner of two cups of leafy salad, a quarter fillet of salmon, and 200g of sweet potato.
Other CR followers might enjoy flour-free bread smeared with baby food.
Reckon this sounds like the work of a skinny Hollywood starlet? Think again.
Perhaps most hearteningly, the CR diet allows for a modicum of rule bending. It's not a question of giving up food, but balancing nutrients, calorie restriction, exercise and lifestyle. In a word, you do what works for you.
Even more intriguingly, those who have endured the diet have extolled the virtues of CR not only on their health, but on their mental wellbeing.
Because of the hormonal changes brought about by the diet (a drop in testosterone levels, for instance), CR practitioners often report a feeling of calm and a renewed sense of youth.
Founded in 1994, the CR Society now boasts 5,000 members worldwide, and the feeling of evangelical zeal is palpable in the community.
A line on the CR Society's homepage (www.crsociety.org) simply reads: "Welcome to what is likely the most important website you will ever visit. Enjoy the journey."
Studies on the effects of the CR diet on human lifespan are still ongoing, yet few can argue that research carried out on animals isn't compelling. Seventy years ago, researchers discovered that reducing the amount of calories fed to rodents nearly doubled their lifespan.
A 25-year study of rhesus monkeys by the National Institute of Ageing in the US published results this year that found concrete evidence of health benefits.
The CR community cites other research that proves a reduction in cardiovascular risk factors and cholesterol levels.
A 2009 research paper also put subjects on a CR diet for a three-month period.
Not only did the subjects lose weight, they also had an improvement in memory.
And, if perceived wisdom states that obesity can lead to a myriad of conditions, among them cancer, heart disease and diabetes, it stands to reason that a lower BMI (Body Mass Index) will go some way towards reducing the risk of illness.
One school of thought believes that long-term hunger makes an organism stronger and more resistant to the ills of ageing simply through constant but mild stress.
Of course, the question looms large: the CR diet may well extend lifespan . . . but at what cost to the actual quality of life?
The long-term adverse effects of the CR diet on humans are still unknown, yet experts have noted that long-term CR dieters may experience menstrual irregularities, infertility, hormonal changes, cold sensitivity and reduced bone mineral density.
Other practitioners have reported a disappearance of libido because of fluctuating hormone levels.
Personal trainer Karl Henry believes that while there are some health benefits to the CR diet, the benefits rarely outweigh the sacrifice.
"The reality is that the CR is another quick fix," he notes.
"I'm not sold on the health benefits of the diet, and I would prefer to tell clients to eat regularly and normally. There's no such thing as an elixir that will help people live forever.
"The fasting element starves the body of calories, resets the system, and burns toxins out of the system. So, from that perspective, there could be some benefits.
"But your metabolic rate drops if you don't get food and you can mess the metabolism up with a long-term regime.
"I have some clients who might go to a clinic for a week and go through a process of low-calorie detoxification.
"This gets rid of pent-up junk in their system.
"It certainly has health benefits but it's controlled and only lasts seven days.
"Apart from anything else, you have no energy on a 700-calorie-a-day diet," he adds.
"Your work and relationships would be affected.
"There is a psychological impact to being so tired all the time . . . after all, even if you're sitting around all day, the body needs 1,000 calories just to work. There's just no quality of life there, in my opinion."
With that, Henry doesn't rate the CR diet's chances of success in Ireland: "I genuinely don't see it taking off here," he states.
"Perhaps it will in the US, where there are plenty of extremities.
"But fitness professionals won't stand behind it and won't give it the time of day."
And of course, with the focus often trained on eating as few calories as possible, a possible link to eating disorders cannot be ignored. Certainly, when it comes to proving that CR and eating disorders are two separate entities, CR supporters make a compelling case.
Where anorexics can often feel judgmental of themselves, and deserving of deprivation, the inner monologue of a CR dieter is different as they want to prolong their life and improve their health.
Adolescent psychologist Colman Noctor notes that while "you can't manufacture an eating disorder", and sufferers are often controlling emotion with food, there are minor links between extreme calorie restriction and the mindset of an eating disorder sufferer.
"Most people who are food deprived don't become settled and calm . . . in fact, the less you eat, the more you think about it," he says.
"Most diets end at 11 o'clock on Monday, and all you've thought about is the Big Mac you'll never have again.
"Part of anorexia is about will and determination," he adds.
"To be able to keep to a regime to that extent, they are perfectionists and diligent.
"While this is different to the CR diet, these dieters are not answering something in themselves either. I'd question someone would want to extend their lives, to diminish quality of life."
Rather, Noctor equates the CR diet with orthorexia; a condition where eating 'perfectly', purely and healthily becomes an obsession of sorts.
"I see plenty of kids trying to live off pumpkin seeds, and this is the point where calorie counting becomes obsessional," he explains.
"Being evangelical about eating clouds our judgment."
When it comes to eating disorders, there is a myth that it is a diet gone too far, but it's much more deep-seated psychologically than that.
An eating disorder, is a communicator of distress and a signpost to loneliness or stress.
"From the point of view of nutrition, anything extreme is not advisable," he observes.
"Moderation is key to any diet if it's going to last. Someone who goes on a calorie-restriction diet wants to it sustain indefinitely. Yet the thing about a diet is that it's temporary . . . you reach a target and then you relax."
While CR followers are vocal in their long-term dedication to the diet, Noctor contends that owing to the extreme nature of the regime, a CR lifestyle is rarely sustainable. Many CR followers would see the regime as a lifestyle rather than a diet; however they surely can't deny its extremity.
"I would think that the majority of people on any diet eventually snap," he notes.
"If people do it for an emotional need, there can be a problem developing there."
Henry is in agreement. "Starving the body of nutrients and searching for a magic cure for a longer life is definitely a less-than-ideal state of mind."
For now, the siren call of a diet that promises a long and healthy life is proving a great lure for a growing number of disciples Stateside.
Experts, intrigued by their glowing testimonials, are awaiting concrete evidence of its appeal with bated breath.
But for now, an insider joke of sorts still holds firm: lifespan could well be extended on the CR diet . . . but without treats and delicacies, life is certain to at least feel that bit longer.