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Some CycleOps comments on the “Noakes Diet”.

There’s been major banter (and worse) on Prof. Tim Noakes’ promotion of the Banting LCHF diet. We at CycleOps are indirectly affected, since CycleOps and PowerTap products are increasingly popular indoor training, energy monitoring and weight loss/management programmes. So we thought we’d add some comments, from a cyclist’s perspective.

Tim Noakes’ writings are fascinating, but maybe the key concepts could have been described differently. He talks about post Ice-Age man being ‘designed’ to eat a low carb, high fat diet when perhaps it might have been better to talk of his adaptations to such a diet based on available food and his method of chasing it to exhaustion using his unique physiology and cooling ability. So man adapted to his environment/primary food source in the same way (as he says) that lions, giraffes, pandas and koala bears adapted to theirs. Evolution at work!

What the Prof doesn’t say, but perhaps means, is that the rapid changes of diet during the agricultural and industrial ages, and particularly in the modern era of processed GM foods, have turned us into the most opportunistic eaters on the planet, and our systems simply haven’t had the chance to adapt further. Nor can they really, since the macro-nutrient content of our diet changes from day to day. No wonder, therefore, that obesity and insulin resistance (IR), according to him, are such problems and why so many of us battle to some degree.

Tim’s recommended solution is to change the diet – as did Banting before him – and return substantially to what we were ‘designed’ for. While this makes intuitive sense, perhaps we also need to consider holistically the other adaptations of post Ice-Age man. To stalk and catch his prey, he must surely also have developed fine energy management skills that enabled him to operate at efficient output levels for long periods? No cheetah like sprints for him!

This would be total sense to anybody who had run the Comrades, or spend 10+ hours in the saddle at the ABSA Cape Epic. If you don’t manage your output levels properly, you simply run out of steam. This all correlates quite well with the old rule of thumb that to burn fat, you need to exercise at moderate output levels. Our abaility to now accurately measure this with our PowerTaps, Indoor Cycles and Power Beams is becoming increasingly important to performance, training and nutrition strategies.

Many cycling couches have had specific feedback on this topic. It seems that a fat burning metabolism can do quite well as output levels of 400-500kj per hour (i.e. energy delivered to the pedals). Of course, input levels will be much higher, because we need to keep the brain and rest of the body working as well – at least some of us do! There fairly low output levels might have been fine for Ice Age man and for slower endurance runners/walkers. but people who pedal, especially those who want to go fast, will sometimes have outputs of well over 1000kj per hour. Can a predominantly fat-burning metabolism deliver energy at this rate?

The experience of many cycling coaches suggests not, which is why most recommend maintaining a predominantly carb-based regime when exercising, especially on long events or stage races. Prof Noakes explains that part of the solution is to “fat-adapt”, and that cyclists who haven’t (for whatever reason) will need to resort to carb’s to help them out. In practice, whether its energy delivery rate or inadequate “fat adapt”, many endurance cyclists seem to be running out of steam on a LCHF diet alone.

I have never had a problem with eating high GI carbs on the bike, although this may be a personal thing. It’s just a question of managing the quantity. A little, often, is the mantra and I am a firm believer in the 60g per hour rule for bigger boys, based on many articles that tell us this is about the best that our digestive system can process at reasonable output levels. Obviously as work rate increases, the ability to process carbs decreases dramatically, the exercise scientists tell us.

On a lighter note, anybody who has had exposure to army or boarding school food, where hundreds of people all eat substantially the same diet – will be very aware of the widely differing responses of individual digestive systems to such diets, as evidenced by memories of the remarkable post lights-out sounds and atmosphere in many hostels or army camp bungalows around the country. It just goes to show that, as in Tim Noakes’ example of how the giraffe cannot possibly sustain itself without the symbiotic relationship with the microbiological contents of its gut, so we too have wide individual variations in the bugs that work within us. As the Prof also says, pro-biotics are also important! But bring on free-range eggs, grain-fed beef and cauliflower rice, perhaps?

Happy training, if spring ever gets here.