Popularised by the 5:2 diet and easier than it sounds, is intermittent fasting the healthiest, most natural way of eating there is?
Intermittent fasting. Even the term sounds slightly terrifying. After all, intermittent fasting (IF) – denying oneself food for a fixed period of time – goes against everything our Westernised selves are used to. We are accustomed to food being available 24/7, from biscuits in the office and fresh produce in the fridge to an abundance of restaurants and shops selling processed, convenient food. We’re often told to eat six small meals a day or at least three balanced meals every few hours. Intermittent fasting sounds unnatural. However, it is, in fact, the most natural form of eating there is.
Today, ‘hunger’ is a dirty word, but it shouldn’t be. A steady stream of experts is reminding us that the human body is not designed to graze all day long, or indeed all year long, and doing so supplies a steady stream of insulin into our bodies, which can cause insulin resistance.
Historically, our ancestors would feast in summer to prepare for the barrenness of the winter months, when their bodies would use stored fat for energy – and diabetes and obesity weren’t problems.
Intermittent fasting limits cumulative calories, simply as the window in which to eat is shorter. That said, it’s not exactly a diet, as IF allows for enjoyable, high-calorie food to be consumed at certain times, balanced out by the body restoring itself through eating nothing for set periods. Some people choose to eat normally one day and fast the next; others will stop eating at 5pm and not eat until lunchtime the next day – a typical, albeit short, fast is between 16 and 24 hours.
Zoe Stirling, nutritionist at C Press, doesn’t do long fasts, but practices some IF methods. “I try to give myself 12 hours between dinner in the evening and breakfast the following day,” she says. “I also tend not to snack and stick to three meals a day, which is very much just a basic form of fasting, but I find it fits in nicely into my lifestyle and keeps me energised.”
Yet it’s the 5:2 diet (involving eating what you want for five days a week, and sticking to around 500 calories per day during the other two) that’s the most common example of IF and has popularised the concept of late, thanks to doctor, journalist and TV presenter Michael Mosley widely documenting his attempt in 2012. George Osborne, Benedict Cumberbatch and Jennifer Aniston are also reportedly devotees.
The science behind IF makes sense. When consuming or digesting food, your body has high insulin levels. Twelve hours after eating, the body enters a ‘fasted’ state, where it begins using up fat it couldn’t previously access; we only reach a fasted state after 12 hours of no food, making IF essential for fat-burning. This, and the belief that IF increases release of the fat-burning hormone norepinephrine, contributes to weight loss, and other health benefits are abundant. Intermittent fasting can help with producing new cells and ridding the body of toxicity, reducing inflammation. It’s also believed that IF enables organs to function more efficiently, working against heart disease and diabetes.
One study in Southern California looked at the effect of fasting in mice. It showed, says Dr Jayne Busby, GP at Bupa’s new Health and Dental Centre in Canary Wharf, Crossrail Place, “that IF can slow ageing and improve learning and memory.” She goes on, “a study in 2014 showed that IF can reduce obesity, hypertension, asthma, rheumatoid arthritis and other chronic conditions.” Busby notes that much of this data is collected from animal studies, and human data is limited – but IF is certainly easy to explore as part of a healthy lifestyle; one simply chooses to socialise on “normal” days.
Other popularised ways of eating, like juicing or eating raw foods only, aren’t necessarily conducive to a normal work or social life. Intermittent fasting is a return to a basic way of living and paring down excess, and is surprisingly mentally satisfying. For set periods, IF rids us of the burden of food choices entirely. As such, many attribute the popularity of the diet plan to a widespread adoption of a post-recession, ‘less is more’ mentality, theorising that it’s part of a growing trend for stripping back our desires to authentic needs and doing away with the excess of the early Noughties.
“People are ever-more aware of the array of negative consequences related to consumerism, whether it’s undesirable impacts on their personal wellbeing, the environment or society at large,” says Maxwell Luthy, director of trends and insights at Trendwatching. “Many consumers are looking to scale back their consumption altogether.”
Obviously, IF can leave you, at least initially, hungry. Some studies, Busby says, have shown it may also reduce fertility levels, and women in particular are at increased risk of IF causing insomnia and increased levels of stress hormones. “Those pregnant, breastfeeding, diabetic, suffering from an eating disorder, taking warfarin or under the age of 18 should not attempt it,” she says.
That said, as part of a healthy lifestyle, intermittent fasting may provide our overburdened bodies a much-needed time to recharge. With an abundance of recipe books and meal plans specifically geared towards the 5:2 along with the weight loss and health benefits it brings, intermittent fasting seems worth a shot.