Last year I came across a Facebook forum for people practising a form of Intermittent Fasting (IF) known as OMAD. One Meal A Day? It sounded unsustainable and extreme. Who could stomach that? A few months on, this April, we discovered exactly who when Twitter CEO Jack Dorsey revealed he eats one meal a day in a short, early-evening, three-hour window. The response was uniformly negative. Rolling Stone called it “bonkers”. But my thinking, by then, had changed: fasting has a newfound credibility, not just from the actual science, but also from the cherry-picking amateur enthusiasts bolting from the internet and celebrity stable. IF has been endlessly hyped by U.S. comic Joe Rogan and a predictable parade of Hollywood specimens. Virgin Radio DJ Chris Evans confessed last week he fasts 12 hours at a minimum and sometimes for as much as 16 hours, confining his eating to an eight-hour window (16:8).
In its annual survey of U.S. dietary habits by the International Food Information Council, IF came top in 2018 and was narrowly beaten only by the ambiguous “clean eating” in 2019. A raft of apps have emerged to help people manage their new fasting lifestyles. One of the most popular, Zero, announced in August it had 2.5 million downloads in two years.
In evolutionary terms and physiologically, OMAD isn’t as loony as it first seems. There are credible, scientifically-backed arguments to suggest that we are suited to eating far more healthy fats and much less regularly than late 20th-century and, indeed, existing government dietary advice suggests.
Scientists at the Salk Institute found the average person’s feeding window to be about 15 hours long, from that first frothy cappuccino to the last little biccie or the whiskey before bedtime. Eating exactly the same obesogenic (read sugary) diet, mice with access to food 24 hours a day were carrying four times the body fat of mice eating exactly the same quantity of food for only eight hours a day. The institute’s 2018 study concluded that “eating in a 10-hour window can override disease-causing genetic defects and nurture health.”
Scientists at the Salk Institute found the average person’s feeding window to be about 15 hours long, from that first frothy cappuccino to the last little biccie or the whiskey before bedtime
However, that was not all that interested me. Studies suggest that a phalanx of health issues, like Alzheimer’s, cancer, polycystic ovary syndrome and the 21st century’s top grim reaper, metabolic syndrome, respond positively to us eating less often. For more day-to-day health issues, blood tests prove that many health markers including LDL and HDL cholesterol, blood sugar levels, inflammation, human growth hormone and a brain performance protein called BDNF can be positively impacted. Less scientific are claims that it will take the human body into a state where it starts to eat its own dead and damaged — read cancerous — cells after about 16 hours. This state is known as autophagy, and the latest advances in understanding it won won Yoshinori Ohsumi the Nobel prize in physiology or medicine. Yet despite promising animal studies, so far nothing has actually shown when and if it kicks in in humans.
Annie Hart, 49, a health coach, usually fasts for 16 hours at a time, but finds OMAD even more effective: “Within a week of doing OMAD, my brain had woken up, I was less depressed and foggy. I thought I was starting the menopause but it turns out I was not, it was how my body was reacting to food.
“I know OMAD is not for everyone. Having said that, it worked so well for me that I now have my 90-year-old father thriving on a two-meal-a- day protocol. I firmly believe everyone should fast for at least 12 hours (best often overnight).”
One of the most high-profile proponents of fasting is Dr. Jason Fung, a fasting expert whose Toronto Metabolic Clinic treats metabolic disorder with fasting and ketogenic (high fat) diets.
In his book The Obesity Code, Fung recommends high fat, medium protein and low carbohydrate meals, spaced many hours apart. When we eat, insulin goes up, instructing the body to store food as body fat. When we don’t eat, insulin goes down, signalling the body to burn this stored fat. Fasting properly, then, is a sure way to lose weight.
Nutritionist Petronella Ravenshear is the author of The Human Being Diet, which she describes as “a blueprint for feasting and fasting your way to feeling, looking and being your best”. She says she naturally thrived on OMAD for most of her adult life (she is in her 60s), until, ironically, being forced into what she sees as the three-meals-a-day-with- snacks dogma while she was training to be a nutritionist, which made it far harder for her to go back to her OMAD habits: “When I do, it’s always worth it.”
It all sounds grand, so why aren’t we all at it? In a word, hunger
She sees the benefits of OMAD as mimicking “the metabolic flexibility in the hunter-gatherer lifestyle versus the metabolic inflexibility of the modern sedentary lifestyle. When we fast, i.e. when we stop eating for extended periods, which was very common for Paleolithic man, the brain is forced into pulling energy rather than storing energy mode, and that’s good for us”.
It all sounds grand, so why aren’t we all at it? In a word, hunger. In my early attempts at OMAD I followed Ravenshear’s recommendation that I give my body a complete rest from eating, and drink only water. I felt desperately denied, a tad deranged even. I managed only 16 hours at the most food-free — the last four of which were a white-knuckle ride of insane longing for a milky coffee with toast and eggs. This continued for a few weeks and I found any excuse to break the fast.
Obviously, I was not a natural OMADer like Ravenshear.
These hunger pangs disappeared when I read Fung’s A Complete Guide to Fasting, which recommends I ward off hunger with bone broth, made with a couple of chicken carcasses costing 70p from the butchers. I boiled them for a couple of hours with herbs and veg, then strained it. I then added salt (for the electrolytes). After that, with a bit of black coffee and green tea, incredibly, the day passed with very little thoughts of food at all. This was my OMAD epiphany. Now I find 18:6 doable most days. If I’m busy and running about, 20:4 is a cinch. Any sign of high stress or a hangover, though, and my eating returns to chaotic.
Yes, a word of warning to drinkers: the eating chaos and rabid hunger always returned after a night of drinking more than two glasses of wine, and after a 50th birthday, my eating fitted less into a window and more into patio doors flung wide open. The snacking returned as did the lack of focus. For this reason, I think a more civilized 16:8 lifestyle is probably best for me. Some days, when OMAD went wrong, my eating was without question verging on bingeing, and that is what makes eating disorder professionals concerned about OMAD and the other more extreme IF trends.
Priya Tew, a spokesman for the British Dietician Associaton, is dismissive of these extreme fasts: “It is unsustainable long-term, so it is a crash diet, which could potentially lead to gaining any weight lost, and more.” Having said that, reasonable restricted-eating windows are, Tew says, a good thing. “It is a good idea to stop snacking and focus on meal times for breakfast, lunch and dinner. And there’s nothing wrong with skipping breakfast if you’re not hungry, as long as you aren’t compensating by eating more midmorning.”
Deanne Goddard, of the National Centre for Eating Disorders, gives OMAD short shrift. “The kind of people attracted to these diets also have poor body image and although they claim that they are restricting their food for health, they’re probably over-focused on appearance. People who live most happily are those who practise moderation, not extremes of any form. They do not impose pain on their bodies to achieve their life goals. It’s well-proven food- restricting diets lead to bingeing, and that rigid dieting systems have a negative impact on both self-esteem and the way we view feel and behave around food.” I mention autophagy, and she says: “I believe they are based on pseudoscience because no one has taken into account the negative impact food restriction of any kind has on the neuro-chemicals in the brain that govern appetite and mood.”
The problem with replicating the eating patterns of Palaeolithic man is that, unlike back in the Stone Age, food is plentiful. Had Paleolithic woman come across a big bag of Burts Crisps in her cave, she would have stuffed them all down, too. Bingeing is a natural animal response to hunger. No matter how thrilling the science in its favour, until we live in a world without wine and Burts Crisps, fasting will remain peppered with edible pitfalls.
Three fasts that are food for thought
TRF, is probably the most widely practised, uncontroversial and easiest fast of all. It basically requires extending the overnight fast by a few hours so that we go without food at times that suit our natural circadian rhythms. The simple rule is, daytime for eating, night-time for sleeping. Many people skip breakfast to eat within an eight-hour window.
Eat, Stop, Eat:
Popularized earlier this decade by a human nutrition graduate, Eat, Stop, Eat is simple. Go a full day entirely without food once or twice a week, and for the rest of the time, carry on as normal. eatstopeat.com
Fast mimicking Pro-Lon:
Developed by gerontologist Dr Valter Llongo, Pro-Lon is a pre-packaged diet that allows a certain amount of food and essential nutrients while never taking the body out of its fasted state. Llongo believes we should all be fasting twice a year, and that his fast should be available on the NHS as a treatment for certain conditions. Should you want to try it, it’s pounds 225 for five days.