Metabolic Efficiency – Initial Bike Testing

Last year I was in Hawaii for 6 months and had plenty of time to train and sit around reading about triathlon. I don’t remember which set of articles put me onto it but I started paying attention to studies that mentioned a high fat diet can help encourage your body to burn fat as fuel rather than rely on the smaller store of carbs (~2000 calories stored as glycogen around the body).

The area of diets is still a controversial topic in the endurance world with some arguing for eating high fat, and others arguing against it. Here’s a good article that’s fairly balanced. I met Nicci Schock through the Gold Coast Triathlon Club in Hoboken, NJ. She is MET-certified in the approach advocated by Bob Seebohar which is NOT a low-carb/high-fat diet but a ‘carbohydrate-controlled’ diet meaning that you are trying to control your insulin response to food by pairing any carbohydrates with high ratios of protein/fat so that the sugar in carbs is processed much less quickly. Generally workout nutrition relies a lot on carbohydrates and with this approach there is no exception. In Seebohar’s approach they advocate using Generation UCAN as the sports drink which has ‘Superstarch’ as it’s main ingredient. Superstarch is basically corn prepared in a special way that makes the release of carbs much slower than other drinks. The theory goes that you train your body to become metabolically efficient and then you consume a (by relative standards) low amount of calories in the form of UCAN. Matt Bach tried this approach and won Ironman Maryland. Last week I went out riding with Matt for 4 hours and all he had was one bottle of UCAN (~110 calories) and a few sips of water and he was steaming along the whole time. Pretty impressive if you ask me.

Generally I try to eat a diet with unprocessed foods and lots of vegetables. That mostly rules out bread, pasta, sodas, etc but is not low in carbs as I’ll throw in potatoes, squash and stuff like that. In the lead up to Ironman Sweden last year I went from 140lbs to 128lbs in the lead up to the race over the period of 6-8 weeks or so, training 20-25 hours/week. When I saw the scales go so low as 128lbs I kind of panicked and felt that my bike power was suffering (or at least failing to go up) so added in more simple carbs into my diet. Within a few weeks I was back up to 135lbs and feeling good. In hindsight I probably just crucified my body’s fat burning abilities! I did not do well in Kalmar, Sweden (DNF’ing halfway through the run) and although I can’t attribute it to any specific cause I figure this might have been one of them.

Anyway, I went to see Nicci to get tested. I sat on the bike for a while pedalling at different power outputs while I wore a mask that measured how much fat I was burning at different levels.

My initial interest was in the power numbers versus my heart rate. I was pretty happy because my heart rate was at 139bpm @ 200w which was my race power target in Sweden. At that time my heart rate would be in the high 140s, maybe as high as 150. My FTP has increased from ~ 260w in Hawaii to about 275w now (I really need to test again!) so it’s not that surprising my heart rate is lower.

The really new information was how much calories I burn at that level and what % is fat and what % is carbohydrates, see below.

Where it gets interesting is the calorie fuelling recommendations. The recommendation was to take in <130 calories/hour at 200w. In Sweden I was aiming for about 260 calories/hour. This is a big difference in my eyes. It worked for Matt so I’m going to try these fuelling recommendations (using UCAN) at American Zofingen Long Course Duathlon on May 17th.

In my head, using my very poor knowledge of nutrition/body chemistry it seems that I should bonk. If I ride at 200w burning 400 calories of carbs/hour and only ingest ~100 then I’m running a deficit of 300 calories. My body can store up to about 2000 calories of carbs. If I’m running a deficit of 300 calories/hr I should be running on empty after 7 hours of racing. The long course duathlon is going to take me 8 hours + so it could be a hard day! I’m going to go all-in and test it out and see what happens. The worst case I’ll take on some Coke and sugary snacks to revitalise me towards the end of the race.

Fingers crossed it all goes well! In any case, I’ll have another set of tests in 2-3 months to see how my metabolism has changed. In the meantime I’m trying to eat carbs only when they are pair to protein/fat with at most a 2:1 ratio. This means if you want to eat 40g of carbs, you should eat at least 20g of protein (or ~10g fat; or; a mix of protein/fat).. Knowing that in the past I have tended to lose weight in this kind of scenario I’m going to try to hold onto my current weight until the lead up to the race and allow it to drop down to ~130-133lb while trying to hold my bike power.

The other way to improve efficiency other than diet is to train in an aerobic zone for extended periods. This test allows me to find where the upper bound of that zone is, and also pinpoints an optimal power zone. This isn’t too different from doing a power test and dictating aerobic zones from that. For me, the potential untapped scope for improvement is on the diet side of things, as I do lots of aerobic training already. For others who train hard all day every day, this aspect might be more useful to them.

Here’s a couple example dinners I’ve made recently:

Veg/Lentils/Leaves with Sweet Potato

Pesto Chicken, Salmon w/ Furikake, Carrots and Brussel Sprouts

2 Eggs, Salmon w/ Furikake, Leaves, Carrots, Cheese and… Japanese Squash for the carbs

Brussel Sprouts wrapped in Bacon

Power Crunch Bars to have when I need a snack that won’t elevate insulin levels