Bringing home the bacon: what happened on my first low-carb ultra marathon
20 hours into the inaugural Oman by UTMB ultramarathon and a 1,000m wall of rock towers over me. Under normal circumstances I would be scraping around for the last vestiges of energy but instead I feel uncharacteristically strong. My ‘Banting’ diet appears to be paying off.
In October I had breakfast with Professor Tim Noakes, leading South African sports scientist and architect of Banting – a Low-Carb-High-Fat (LCHF) diet. “There is no benefit to eating carbohydrates,” Noakes told me. “I would recommend a low carb diet for all endurance athletes, 100pc.”
That’s a bold claim – traditionally, runners relied on a constant stream of carbs for their energy – and it’s fair to say that Noakes is something of a divisive character. Hundreds of thousands of devoted supporters follow his every word on social media and credit him with changing their lives; but many in the medical establishment see him as a contrarian. Indeed, the Health Profession’s Council of South Africa (HPCSA) took him to court for giving “unconventional advice” – although Noakes won the high-profile case and subsequent appeal
In the world of endurance sport Noakes and his fellow LCHF advocates have a loyal and growing following. Jason Schlarb, professional ultra-runner and eventual winner of the Oman race, is just one of several elite athletes who have torn up longstanding sports nutrition guidance by switching from carbs to fat. His explanation is simple: “I just find it works better for me. I have more energy and can go on for longer”. Schlarb is even sponsored by Epic, a Texan cured meat company.
With so much conflicting advice, there seemed little alternative than to put the theory to practical test. For six weeks I, along with my long-suffering partner, attempted to cut out all carbs and switch to a high-fat diet.
Gone were the sugary cereals, stacks of toast and mounds of rice, pasta and potatoes. Instead each day started with bacon, eggs and avocado, lathered in butter. I eschewed the office lunch in favour of solitary meals eaten out of Tupperware, usually containing hearty meat, cheese and nut salads. Dinner consisted of more meat and plentiful local vegetables. On social occasions I became a low-carb-beer-drinking diet-bore.
Previously, such a regime would have seemed unfathomable. Like many endurance runners, I suffered from constant hunger and would eat throughout the day. It’s an experience Schlarb says he knows well: he describes how he used to wake up in the middle of the night needing to eat.
But I was shocked by the ease of the transition. Having switched to high-fat, I now found myself content with three modest meals daily despite a heavy training workload. Far from fighting the urge to snack, I simply wasn’t hungry.
The real test, however, would be whether fat could fuel me through an endurance challenge; and there could be few better than Oman by Ultra Trail of Mont Blanc (UTMB)– 137km of rocky Arabian mountain trails with 7,800m of cumulative ascent.
The original UTMB is Europe’s most famous ultramarathon, bringing together the best mountain runners every August in Chamonix for a 100-mile lap of the mountain. Now they have brought elite mountain running to the Arabian Peninsula, combining French professionalism with Omani hospitality.
The starting-line in Birkat Al Mawz on Thursday evening was an incongruous sight. Ultramarathons are a new concept in rural Oman and the local men, dressed in ankle-length white dishdasha, looked on perplexed. Traditional dancers waved swords wildly in the air. An enthusiastic Irishman provided commentary and a strong field of international runners with head-torches, backpacks and tight shorts shuffled around nervously. Some would be out on the course until Saturday afternoon.
Within the first few hours the scale of the challenge became apparent to everyone involved. We clambered in and out of dry wadis, along precarious exposed ledges and over rock-strewn mountains in the darkness. This was extreme by any standards. As a clumsy runner I repeatedly tripped over misplaced stones, bruising my legs and arms and swearing vainly into the empty night.
At 5-10km intervals checkpoints staffed by friendly local volunteers provided a selection of sugary foods and drinks. For most runners this is the fuel for their engines – regular doses of quick-release carbohydrates. Instead I ate sparingly and stuck to real food: delicious local dates and nuts, bananas, dried meat and a few biscuits. I drank mostly water with an occasional Coke to provide me with a much-needed caffeine fix.
By morning, nearly 40pc of the 324 participants had dropped out, some injured, some disorientated, some sensibly deciding that enough was enough. Many were successful finishers of the original UTMB race but had underestimated the unforgiving terrain. Ultimately fewer than half of the participants would finish the race. I meanwhile, having eaten a fraction of my usual amount, was waiting expectantly for the inevitable crash in my energy level.
At the 80km mark I scrambled up a 600m cliff, one section of which required donning a helmet and harness and scaling a via ferrata. Perched at the top was Alila Jabal Akhdar, a luxury hotel that blends into the mountains. Here, for the first time in a race, I ate a proper meal – rice, lentils and chicken – before heading back out onto the course.
We had been warned of the final climb, but nothing could have prepared us for the ascent from Balad Sayt. In just 3km the ‘trail’ rises 1,100m followed by a cruelly deceptive respite and then another 600m up. By now the midday sun scorched down and it was gruelling work, requiring hands, feet and nerve.
Halfway up I found a lonely Lithuanian runner sitting silently on a rock, fatigue taking its toll. We greeted each other briefly, and I then continued to the top of the cliff before beginning the long and bumpy descent to the finish line in Al Hamra.
In the early evening darkness, a crowd of Omanis cheered loudly, having apparently embraced us ultra-runners. Someone handed me a rose as I approached the line. After 23 hours, the Irish commentator announced my arrival. I felt the familiar cocktail of emotional fatigue and elation building up inside me, soon replaced by hunger as the smell of grilled meat wafted over the enclosure.
My muscles and feet were bruised and battered (sadly no diet can compensate for a lack of training and poor downhill technique) but I remained energetic to the end, finishing in an improbable 5th place – way ahead of anyone’s expectations and in front of many stronger, more experienced, better prepared athletes.
Strava tells me that I burned nearly 20,000 calories in 23 hours. I estimate that I ate 3,000 during that period – which is only 500 more than the normal recommended daily allowance for a man. The reason, according to Noakes, that my body could cope with this deficit is because I had trained it to run on fat rather than carbohydrates. A mere 2.5kg of body fat would suffice to make up the difference; true to form, when I weighed myself, I discovered that I was indeed a couple of kilos lighter.
Does this prove that a high-fat diet is better? The truth is that I’m only one runner, and decisive nutritional research is notoriously difficult, particularly for athletes. Randomised controlled trials are expensive and unpopular; the impacts of diet can take years to materialise; and placebo (and nocebo) effects are hard to avoid. My interview with Noakes might even have functioned as a sub-conscious pep talk.
It’s quite possible that my experience in Oman was coincidence or self-deception or that I am atypical. Extrapolating is risky. But I certainly won’t be reaching for an energy gel anytime soon.
For any other endurance athletes who struggle to sustain their energy levels in long races, who battle digestion issues, who fight to control their appetites or are concerned about sugar consumption or who simply prefer real food, experimenting with a high-fat diet might be worthwhile. And what better place to test it than the 2019 Oman by UTMB, which will offer an even tougher 162km version as well, mercifully, as several shorter options.
Information about Oman by UTMB can be found here. You can follow future running and eating exploits from the author on Instagram @jogonalfie.