How to win the Ironman on LCHF
Bevan McKinnon, aged 43, just smashed the age group field at Ironman NZ. He set a personal best of 9.00.59. Not bad for an old guy with 8 weeks of specific preparation. Here I report back on an interview I’ve just completed with Bevan. We have been working with Bevan for a couple of years now at AUT Millennium in our high performance labs, trying to understand how we can tweak the LCHF approach to become a fat burning machine.
I’ve previously written about Bevan’s 2013 Ironman NZ preparation. We had great lab performance data (moved form 130 W to 300 W power output for a 50/50 carb and fat fuel use), but were a couple of tweaks off converting that into a stellar race performance. Bevan was leading last year throughout the bike and faltered on the run with severe cramping. After assessing what could have been contributing factors in the onset of cramp, Bevan altered his race nutrition plan this time to include more electrolyte and grams of CHO per hour than he’d consumed in 2013. This nutritional tweak was a small but significant change.
Back to 2014 race day:
|Swim: 3.9 km||51:53|
|Bike: 180 km||4:58:36|
|Run: 42.2 km||3:04:11|
First age grouper home by almost 15 mins, and inside the top ten including all pro athletes. Even better were his run splits which were incredibly consistent and Bevan never came close to running out of fuel.
Run Details Division Run Leader | Division Rank: 1
|7.4 km||7.4 km||31:22||6:28:10||4:14/km|
|14.2 km||6.8 km||28:29||6:56:39||4:11/km|
|21.3 km||7.1 km||30:04||7:26:43||4:14/km|
|28 km||6.7 km||29:51||7:56:34||4:27/km|
|35 km||7 km||32:13||8:28:47||4:36/km|
|42.2 km||7.2 km||32:12||9:00:59||4:28/km|
OK, he’s a really classy athlete and was anyway. But LCHF and fat adaptation have taken him to a whole new level. Here’s the full story….
“I started some focused Ironman build up after Xmas. We went to the States for a holiday, and it was early January. Obviously I was fit anyway, but nothing specific in terms of Ironman preparation.”
So what did training look like?
“On a couple of weeks I got up to about 25 hours of actual training. I was swimming sessions up to 5000 m with 18-20 km a week of swimming. I knew I had to get that amount of swimming in to get to the low 50 min mark for the Ironman distance. Biking included a long aerobic ride. I did end up biking to Tauranga to watch the Port of Tauranga Half (a 280 km ride). I would do a weekly “sweet spot” ride on the bike, usualy mid week. Running wise, all of my running was aerobic, and I never ran more than two hours in any one session. In saying that, I did do a week where I did two by two-hour runs. That said, I did include three or four threshold type runs in the whole preparation. These were on a grass track typically 40 min workouts, say 8-10 by 800 m with 200 m float in between, and only when I was feeling fresh enough to do it.”
When you look at Bevan’s Training Peaks data, he is very careful about recording and watching his output. He was quantifying his weekly work in daily “critical training load”. This is the TSS (Training Stress Score) score and he was at around 150-160 TSS a day. This is qute a big load. Remember, a TSS of 100 is the equivalent physiological demand of a 1 hour time trial. He maintained that on most days for 6-8 weeks, with some periodisation for rest of course.
Heat chamber: Bevan used the heat chamber at AUT Millennium to develop some heat adaptation and increased blood plasma volume during the taper phase leading into IMNZ. He says “I think this was also key as I was about 5 bpm down heart rate for the same power output after the heat training.” Heat training is known for these effects in increasing blood volume and reducing viscosity.
Training take homes: This was not a minimalist training approach. Bevan trained long and put in some very big weeks. The demand was high, but the output carefully monitored on Training Peaks. When his output dropped off, he recovered. Recovery and adaptation is how you improve.
Bevan has been on a low carb high fat diet since November 2013. I think that is important as my feeling is now that longer-term adaptations are required to make the full shift and to optimise benefits in metabolic efficiency and fat burning. His diet is typically three reasonable meals a day with protein from animal sources usually along with a very high vegetable intake. He uses coconut oil, olive oil and butter as his major extra sources of added fat. He avoids industrial seed oils high in Omega 6. His diet is high in fish, eggs and nuts.
Leading into the race there was no special carbohydrate loading or any particular change in diet, apart from some extra kumara (New Zealand version of a sweet potato) in the few meals prior to race.
- Dinner the night before: Roast pork with crackling, vegetables, kumara
- Breakfast: Small amount of high fat yogurt, banana, protein powder.
“One great thing about LCHF is my new found ability to get my weight under 80 kg” says Bevan “I’ve always trained quite a bit, and never ever been able to get my weight less than about 82 kg. That’s just too heavy for Ironman racing, especially the run”
In other words, this diet allowed Bevan to get to a race weight aligned to actual high performance Ironman racing for the first time in his triathlon career. It is interesting that he was unable to get near this weight previously despite training up to 30 hours a week.
Race day nutrition
Here’s the big change made. The race fuel wasn’t fat, it was 20 gels and 1.5 bottles of coke on the bike leg. On the run he started with a handheld gel bottle holding 4 gels. At the halfway he collected another bottle but ended up not using that and went to a combination of coke and water after that.
Remember as you read below that carbs, especially in the rapidly absorbed form such as gels, boost blood sugar and insulin production. Insulin turns off fat burning and promotes glucose burning.
Bevan had discovered, for himself at least, that once he was well fat adapted, that when he was riding at around 270 W power output then the extra gels didn’t end up dialing down his fat metabolism. He was still around 50% fuel by fat and 50% by carbohydrate. We feel that the whole Kreb’s (fuel) cycle in the body was spinning fast enough and fuel utilisation was high enough that insulin wasn’t being secreted in massive amounts to dial down fat burning and promote glycogen only fuel use. This isn’t what you see in non-fat adapted athletes. Nor is it what you would see in Bevan at rest. This was a key discovery as he could get the performance benefits of the carbs whilst still maintaining the fat burning that he had developed through his LCHF and mainly fasted long aerobic training work.
Bevan never really practiced using that amount of carbohydrate on any of his build up simulations. Only in a practice half ironman in January did he do the same thing (he won that race too). Many sessions were fasted or with no food. Train low, race high?
Take home: Bevan at least can tolerate quite a lot of carbs during the race (600g or 2400 kcal on the bike). This didn’t dial down fat burning for this fat adapted athlete. This maximised his performance. It probably didn’t do his health any good for the race day itself. That’s probably because of the oxidative stress he put himself under, but I’m not thinking Ironman racing is a health kick.
The race itself
“I just felt strong the whole way” says Bevan “I got off the bike after doing 170 of the 180 km solo and my legs felt brilliant. I just started running and felt I could keep it up for the whole marathon so away I went”.
This is fabulous, as anyone who knows the Ironman New Zealand bike course – it has mostly gradual climbs, usually a headwind on the two return legs from Reparoa (strong winds this year). Bevan describes the road surface as a “cheese grater ride”.
“I had no “dark moments” at any stage in the race. I had enough fuel to simply keep going. In the end I was suffering some minor muscular soreness on the ups and downs of the run course which slowed me slightly. I wasn’t aiming for a specific time, and it wasn’t until the last seven kms that I realized I had the chance to go under 9 hours, which I just missed out on in the end” says Bevan.
Bevan ended up even stopping during the bike ride to go into the toilets and have a pee. Frankly I was astounded by this, as any triathlete of this level usually just “goes on the run” so to speak. So there’s a couple of minutes that might have pushed him under the 9 hour mark. Who knows?
Overall take homes:
- The LCHF nutrition approach is feasible for high performance endurance racing including Ironman
- The application at this level requires carbohydrate ingestion during the event itself
- Carbohydrate loading wasn’t necessary
- Heat chamber training may have been beneficial for performance
- Monitoring training load and output during training and racing was useful, especially power on the bike.
- The low carb lifestyle is something that Bevan has been able to maintain and he does so during his regular working and coaching life regardless of the performance benefits. He has suffered hyperlipidemia to the point his doctor was recommending medication on his high carb athlete diet previously. These issues, especially around triglycerides, have resolved with the LCHF approach.
Finally congratulations. This was an astonishing effort. AUT and our high performance team are proud to have been involved. That said, it was Bevan’s drive, work ethic and attention to detail which made the real difference.
Our athlete and nutrition services are available to the public. Click here for athlete clinics, email us for nutrition.