The practice of fasting is as old as culture itself. From the Native American custom of reducing food intake before a vision quest, to the ancient Greek habit of withholding food from sick patients, fasting crops up again and again in human history, especially in the context of religion. The Jewish forego food at Yom Kippur, as do followers of Islam during Ramadan, and Christians frequently give up some favourite food for the period of Lent. Hark back even further in our evolution and fasting was not optional - early humans went without food unless they foraged or hunted it down, and then they gorged on it to tide them over.
Old trick, new evidence
In the last decade, the concept of fasting has experienced somewhat of a revival. As the evidence stacks up at the altar of Science, intermittent fasting is being recommended in books and blogs by doctors, nutritionists and health coaches. Its myriad benefits, so they say, include weight loss, improved brain functionality, reduction in insulin resistance, appetite and metabolic regulation, a slowing of the ageing process, and even reduced likelihood of Alzheimers and Parkinson's disease. Sounds hyped, but in fact there is solid research to support these health claims, particularly on the link between fasting and weight loss. One typical study found that overweight adults who reduced their normal calorie intake by 20% on alternate days lost 8% of their body weight over the course of eight weeks.
The principles of intermittent fasting are simple. Normal eating is broken up with periods of significant calorie reduction. That being said, there are umpteen approaches to fasting, and for every approach there are another umpteen books. The 5:2 diet made popular by science journalist Michael Mosley seems to have gained more traction than most; it suggests five days of reasonable eating, offset by a restricted calorie intake of up to 500 calories for the other two days of the week. Mosley has built an empire around this 5:2 structure, offering various 8 week programs on his website. Another popular program, Lean Gains, promotes fasting for 16 hours and “feeding” for eight by skipping breakfast and lunch, then having your biggest meal in the afternoon. Whichever specific plan you follow, the gist is you can’t just eat donuts five days a week and expect all the benefits of fasting to follow. For optimal results, your diet on the normal eating days should be heavy on vegetables and good fats, low on sugar and empty carbs.
Stop, eat, eat, eat
In theory, this all sounds good so far. Many of us, though, have experienced first hand the inevitable post-diet pig out, and fasting can often lead to a similar bloated end. A 2010 study found that mice who fasted two days per week but were allowed unrestricted access to food the other five days tended to overeat on those days, cancelling out any benefits of the fast. Research shows similar patterns occurring in humans, leading some to suppose that we (mammals) are hardwired to respond to periods of restriction with unbridled gorging. Amusingly, doctors in Abu Dhabi report a dramatic spike in hospital admissions caused by overeating during the evening meal in Ramadan, a phenomenon they say occurs year in, year out.
Fasting vs. restricting
Not so amusing is the similarity between intermittent fasting and the restrictive behaviours of anorexia sufferers, or the restrict-binge cycle of bulimia and binge eating disorder. In The Management of Eating Disorders and Obesity, ED expert Steven J. Romano describes the progression of seemingly healthy behaviour into full blown disorders. Commonly, his patients start with 'normal' food restriction, such as fasting or cutting back on empty carbs, however they cross over into eating disorder territory when the restriction becomes an obsession, often involving constant monitoring of body weight. Eating disorders are a complex topic with more grey area than black or white, but suffice to say, intermittent fasting may do more harm than good to those prone to disordered eating.
Is fasting right for me?
Critics of intermittent fasting will point out that the research is by no means comprehensive - most studies are still conducted on animals, and the long-term effects are yet to be determined. Furthermore, current research shows that an overall reduction in calories (spread out over seven days) is just as effective as fasting for both weight loss and lowering the risk of disease. How you reduce your calories isn’t so much the issue as what and how much you eat. Eating the appropriate amount for your body and reducing your intake of trans fats, refined carbs and refined sugars is what counts in the long run.
If you're up for giving fasting a go, seeking professional advice can certainly be a good way to ease into it. Perth-based nutritionist Jo Beer offers a personalised 5:2 eating plan, with meal suggestions featuring local producers such as yours truly and Pure Glow. Mosley’s Blood Sugar Diet programs offer plenty of online support and resources such as recipe inspo. Health professionals generally agree that those who fall into the following groups should consult a doctor or avoid fasting altogether:
- History of eating disorder (current or otherwise)
- Type 1 Diabetes
- Psychiatric disorders
- Aged 18 or under
- Pregnant or breastfeeding
- Frail or recovering from surgery
Everyone’s lifestyle is different, as is one’s relationship to food. What works wonders for one person, will be a nightmare for another! Fasting might just be the kick up the bum you need to shift a few kilos, but if you’re prone to disordered eating, best sit this one out.
If you are suffering from an eating disorder, you're not alone. There are estimated to be 1 million people in Australia at the moment who are experiencing disordered eating. Head to The Butterfly Foundation to learn more.