As most of you who follow my social media posts, and occasional blog posts, will no doubt know, I follow the #OFM (optimized fat metabolism) approach to race nutrition and my diet in general. I believe that for many out there, not just athletes, the high fat, low carbohydrate, ketogenic approach can confer significant health benefits in terms of weight management, chronic disease risk reduction, and potentially the reduction of cancer risk.This excellent podcast by Dr Dominic D’agostino is very compelling and well worth an hour or two of your time.

For me, as an endurance athlete, I truly believe that the changes I’ve made to become a fat adapted, low carb athlete, have not only improved my lab data (see my lipid values post here but have also helped me drop a few pounds and improve my body fat percentage. I look leaner than I ever did in the past following the conventional high carbohydrate athletic diet, and the reduced weight has allowed my running performance to steadily improve. At age 45, it’s unlikely that I’m going to win many ultra competitive races (though I did post wins at the Elkhorn 50 and Blackspur ultra 100km this season) but I am still competitive.

OFM is the term coined by Peter Defty from Vespa. Peter is a big believer in the high fat, low carbohydrate approach to health and performance, but he also sees the benefits of strategic carbohydrate use, particularly when racing. The science is there, and the recently published paper by Jeff Volek, is a credible addition to the literature.

I won’t go into all the details you can read about it here suffice to say that there is now little doubt that ‘fat-adapted’ low carb athletes are able to tap into their body fat stores to fuel their performances at rates that were previously thought to be impossible. Potential benefits include a relative preservation of muscle glycogen stores for longer events, translating to a diminished need for fueling during prolonged activity.

The commonest reason for ultra runners to drop from races is GI distress. So a lower fuel requirement could potentially lead to a lower rate of gut issues. I quote from Outside magazine:

“GI issues are the most common reason runners drop out of 100-mile races, according to Kristin J. Stuempfle, a professor of health sciences at Gettysburg College in Pennsylvania. During a recent presentation at the Medicine and Science in Ultra-Endurance Sports conference, Stuempfle cited endotoximea—when molecules normally confined to the GI tract leak into the blood—as a likely cause of severe stomach problems.   Although the exact triggers of endotoxemia are unknown, many experts speculate it is related to reduced blood flow to the gut. But Laye feels differently. He thinks endotoximea has more to do with the constant jostling of fluid and food caused by running. “You hardly, if ever, see endotoxemia in cyclists,” he says, “and my hunch is that’s because cyclists are not bouncing up and down.” 

Your best chance of thwarting GI problems during a race is to train your gut by practicing your fueling plan during training. Still, Laye says about 60 percent of competitors experience nausea at some point during an ultramarathon. If you do vomit, he says, “the only strategy is to keep eating and drinking. Aim to replenish what was lost ASAP.”

For me, I have found that since I switched things up, I can get by on less race fuel. Less fuel means less fluid sloshing around in my gut, and less GI distress. And the beauty of the OFM approach is that I can live a low carbohydrate lifestyle most of the time, but race on carbs! You get the best of both worlds. Peter Defty describes fueling on carbohydrates in the race situation as being akin to consuming rocket fuel. Much like there is evidence that low caffeine consumers have more to gain by using caffeine before racing than habituated caffeine drinkers, perhaps the same is true of the low carbohydrate cohort.

I initially played around with a variety of readily available carbohydrate rich sports drinks - all the usual suspects - gatorade, powerade, heed, cytomax, e-load etc. Eventually I decided to try the Generation Ucan products, after listening to Dr Peter Attia, who is a big advocate. After using it in training and racing though, I found I had a lot of gut distress in the latter stages of races, and in fact it was pretty unbearable for me for a couple of days after racing. I chatted with the Vespa guys, and it was suggested that Ucan can in some individuals ferment in the lower GI tract, causing gas, nausea and bloating - something I can attest to. Peter Defty suggested I try Vitargo whilst racing.

Vitargo is an interesting product. Developed in Sweden, it’s a patented low osmolality, high molecular weight carbohydrate, consisting primarily of amylopectin starch. The predominant advantage of Vitargo is that it is rapidly absorbed from the intestine.

A 2000 study, Muscle glycogen resynthesis rate in humans after supplementation of drinks containing carbohydrates with low and high molecular masses’ Eur J Appl Physiol 81:346-351 showed that Vitargo replenished muscle glycogen about 70% faster than other sports drinks.

A second study, Improved gastric emptying rate in humans of a unique glucose polymer with gel forming properties’ Scand. J. Gastroenterol 2000;35:1143-1149 showed that Vitargo very rapidly exits the stomach, a property which limits the potential for GI distress.

I’ve been using Vitargo S2 for the last 6 months, and in the interests of full disclosure, I am now a sponsored Vitargo athlete. It may not be for everyone, but it is certainly worth a try if you’ve been troubled by gut distress when racing. Not only does Vitargo taste great, but for me it works like no other sports drink I've tried. I am now following a largely liquid race fueling strategy, supplemented by the occasional gel, which I seem to tolerate fairly well.

You will see from the Vitargo website that S2 can be used pre, during, and post workout. Here’s my approach:

I do not use Vitargo before my low intensity training runs - about 80% of my training, unless it’s an unusually long session. Typically I get by on zero calories if I’m out for less than 3 hours, but if I have an interval workout planned, I will use 1-2 scoops of Vitargo S2 30 mins before heading out. If I am out for 3+ hours, then I'll begin fueling with Vitargo at around the 2 hour mark.

If I run for over 2 hours, or if there is significant intensity, I will use 1-2 scoops of Vitargo in the immediate post run period, to aid in restoration of depleted muscle glycogen. Ideally it should be consumed within 15-20 mins of finishing, and this really goes for any kind of post workout carbohydrate ingestion. I will add whey protein to Vitargo if it is a prolonged or hard session, and I will always use additional whey protein if I have been in the weights room. There is a Vitargo Post product with contains protein, though it has been hard to come by lately!

During racing, I will use Vitargo at every crewing point, most of a standard bottle downed in one go, and I am now carrying the Vitargo single serving packs whilst racing to mix on-the-go.

My day to day diet, is really a high fat low carb affair, but if I am racing an ultra the next day, or if I know I have a long day in the mountains planned, I will consume extra carbs the evening before.

So that’s my approach. It seems to work in terms of minimizing GI issues, maximizing energy levels whilst racing and in speeding up my recovery. Of course, everyone has their own approach. I would be definitely interested in what kind of approach others are using.