In part 1, I discussed on how a low-carbohydrate diet seems to be healthier. But remember that there are no real definition of what is a low carbohydrate diet. For me, based on the research paper that I’ve read, RDA levels and our paleo ancestors, I would put the threshold below 35% or for a 2000 kcal diet, that is about 175g of carbs per day. To be honest I’m not even there and my diet usually fluctuates between 80g and 160g. The majority of my carbohydrate intake comes from fruits (2 servings per day) and dairy, while potatoes and rice and whole grains, I eat more rarely, mostly when my training is either high intensity or longer. Oh, and I forgot to mention wine and dark chocolate…Am I suppose to tell you that?
But what about performance? We all know that carbs are necessary to perform well, especially at high intensity. Carbohydrates in the form of glycogen is our reserve for when the lion attacks and we need to run fast! So when we are out of glycogen and our blood sugar drops, we fatigue. Carbohydrate are so wonderful that when we swish a carbohydrate solution in our mouth, it has been shown to improve performance, even for 1 hour events when carbohydrates are not really needed. On the other end, other studies have also shown that training with low glycogen or carbohydrates on board activates mitochondrial gene expression, which in turns will improve training adaptation.
Recommendations for performance
Currently the recommendations for optimal performance stands at 8-10g/kg daily of carbohydrates. If you do the math, taking me as an example, that would be 560g or 2240 kcal of carbs. Basically on a day where I exercise for 1.5 hour at moderate intensity that is my whole calorie intake for the day! Ten bagels, here you go. OK, I’m being a little bit facetious but if you look deeper into the litterature, these recommendations are for athletes who actually spend a lot more energy per day such as Tour de France cyclist or someone who exercises 5+ hours per day. I would probably fall in the 6 g/kg/day or 350g carbohydrate per day with my 1.5 hour of exercise. That is still a lot and I consume less as mentioned earlier. These recommendations stems from research that is not wrong in essence but we need to look at how it is done. First of all these studies are done with athletes that use carbs as their main fuel, they are not adapted to a lower carb, higher fat diet and if they are, it is not for a long time. Even if you adapt for 5-6 days you don’t get the full benefits of athletes who have been going at it for a long time, as you will see below. So basically what the researchers do is that they take an athlete, have them exercise for however long and then measure glycogen after the exercise bout. Then they look at how much carbohydrates are needed to reestablished normal levels. The thing is if you don’t use as much glycogen because your metabolism oxidizes a lot of fat instead of carbs then you’ll need less to reestablish current levels. Does that make sense? In essence they are not wrong, you will need that amount of carbs if you are a high carb burner, but if you burn more fat probably not.
Actually the research is starting to take off in the low carb high fat department. Let’s look at the preliminary results of the FASTER study. They looked at two different elite athlete cohorts participating in ultra-marathons. One was on a high carb diet (60%) and the other one was at 10-12% in carbohydrate. If you look at the difference in fat oxidation between the two cohorts, it is huge! The HFD oxidized 50% more fat than the high carb. How long did it take them to get there? You have to have mitochondrial adaptation, higher intramuscular triglyceride (fat) storage, changes that do not happen overnight even if your fat oxidation per se can increase very quickly because of a change in your diet.
Now let’s look at what are the requirements during races. It is on average 1g/min of carbohydrate or 40-60g/hour. It is not reported per kg because the limiting factor is our gut, above that level carbs do not get absorbed very well. However, you can train your gut to absorb more carbohydrates to a certain extent. This is definitely too high for me and on average during triathlon and other events I’ll have about 20g/hour of carbohydrate with some proteins and fats for longer events.
And then for recovery the suggestion is 0.8 to 1.2 g/kg with some proteins, the sooner the better, within 30 min. to 2 hours. Again this seems a lot to me for a 90 minute session of exercise. But as sessions get longer and harder this is not a bad place to be if you can add at least the same amount of protein in there.
And now that I’ve shared with you how I use carbohydrates compared to the requirements, how is my performance in all of this?
For the Half-Ironman:
On the bike every 30 minutes: 1/4 of Bonk Breaker protein
at 1.5 hours on bike: 2 scoops of UCAN*, sipped for 20 minutes
at 2 hours on bike: 1 shot of espresso, 80 mg caffeine
at the beginning of run: 2 scoops of UCAN
1 hour into run: 1 shot of espresso with caffeine (See my blog on caffeine!)
*If you are not familiar with UCAN, it is this slow release corn starch that enables to maintain steady blood sugar.
Total calories: 630=114 kcal/hr
Total carbs: 121g carbs=22g/hour
For my last Olympic, I just had a packet of UCAN for the whole time, and that is it simple: 132 kcal, and 13g/carb per hour. Of course in all those strategies I make sure that my reserves of glycogen are full by having appropriate meals the day before and a breakfast or snack before the race. Again I’ll use UCAN in a shake with 5g protein and some fats an hour before the race starts. In comparison I used to have 30g/hour of maltodextrin and other sugars and would totally bonk on the run. Maybe if I could have ingested more carbs I would have done better but I just could not stomach it.
So what is the difference between now and then is that I am now more metabolically efficient! Of course I did not go at it by myself and got the help of Dina at eNRG Performance. In my next blog, I will talk about testings you can do to know how metabolically efficient you are.
Talk to you soon!