Ironman Nutrition: Just How Many Calories Will I Need?

Over the past several weeks i have been using a calorie counting site called My Fitness Pal to keep track of what i am putting into my body.  It has been a powerful tool in making sure that i am getting enough proper calories to power my training.

But what about on race day?  At my first half-Iron triathlon in 2008 i did only a fair job at keeping up with the nutritional requirements of such an endeavor and the last half of the run was not fun.  i ended up in the medical tent.  Later that year at my first full Iron i did a much better job and had almost a perfect race nutritionally.  In the picture at left you can see me right after i picked up my special needs bag about halfway through the bike leg.  In it i could put whatever i want.  i hardly remember but i'm sure there was extra gel, PBJ sandwiches, pretzels, energy chews, and the like.  This leg is often called a rolling buffet and its purpose is to get as many calories as one can stomach before the more gut wrenching run is at hand.

How many total calories did i consume that day?  No idea.  How many should i consume during my next Iron challenge?  No idea.  So i should probably have a plan, no?  Yes.  Let's get to it.

The harder i push during the race, the sooner i can get to the line for a slice of pizza and some ginger ale, but until then it'll be a losing battle trying to keep up.  Twelve hours (i hope) of vigorous effort will require so much more than i'll be able to ingest, but why not try to get as close as possible?  So what might that look like?

Let's say that for my age, sex, weight, fitness level, etc. that my normal metabolic burn for twelve hours (hope hope!) is 760 calories.  That is just a guess, but so is all of this.  Still, better than nothing.  Next, if i search around for some online calculators and average them all out, maybe i will burn 820, 4500, and 3000 calories in the swim, bike, and run legs respectively.  That all adds up to 9,080 calories.

9,080 calories could be replaced by one of the following:
1) 82 chocolate chip cookies,
2) 65 bowls of Breyer's Oreo Cookies and Cream Ice cream,
3) 29 pieces of  Deep Dish Pepperoni Pizza from Gino's East of Chicago, OR
4) 9 Chipotle Barbacoa Burritos with Rice, Black Beans, Tomato & Green Salsa, Cheese and Sour Cream.

i'm having some cravings.  Moving on...

Trying to be more realistic, how many PowerBar Strawberry Banana gels would i need?  At 110 calories a shot, it'd be 82.  Seems like i'd enjoy the aforementioned cookies a little more.  i do remember in 2008 taking 1 before the swim, 9 on the bike, and maybe 5 on the run.  That gets me "only" 1,650 calories.

OK hold on.  Before i continue, i'm wondering how many calories i should really shoot for on race day.  9,000+ seems impossibly high.

i found a calculator that "uses fitness, intensity, distance, weight, and use of fat vs. glycogen to calculate an approximate amount of total calories required for the event."  It can be used for anything from a Sprint to a full Ironman.  It estimates that i will burn 8,320 calories -- 36.31% from fat -- requiring 5,299 calories from glycogen.  Adding in some wiggle room, let's make it 5,499.  Let's say that going into the race, i have 1,800 calories in my glycogen stores.  That leaves a requirement of 3,699.  That seems more manageable.  Now how to manage it?

Well, as much as i wish the kayak volunteers served pizza, i won't be taking in any calories during the swim.  Let's say i am then on the bike and run courses for 9.67 hours (hope hope hope!).  That means i will need 383 calories per hour during that time.

So maybe i tape 9 gels to my bike, grabbing one every 12 miles or so.  (Cumulative calorie total: 990).  i down 8oz of slightly watered down Ironman Perform every 45 minutes or so or about 61 oz. or around 457 calories (now i am at 1,447).  Throw in a PBJ "Uncrustables" sandwich (210 --> 1,657), a pack of Clif Shot Bloks (200 --> 1,857), and 400 calories of a "food to be named later" (400 --> 2,257).

Now on to the run.  Perhaps i can choke down 5 more gels (550 --> 2,807),  40 more oz. of Perform (300 --> 3,107), 8 oz. of Coca-Cola (100 --> 3,207), 6 oz. chicken broth (59 --> 3,266), a banana (105 --> 3,371), half a pack more of Shot Bloks (100 --> 3,471) aaaaaaaaaand, um, wow i really don't feel like eating any more.  i am 228 calories short and i haven't even checked my math.

Close enough?  Maybe, but i should really find a way to eat more on the bike.  Still, that makes me feel a little better than i have a chance at keeping up with my nutrition.

So i am done!  Oops, wait.  What about water and electrolytes?  If i don't have a proper intake there, i will bonk before i even have a chance to eat.  Hmm, i think i'll save those calculations for a bit later.  i'm going to have a big bowl of cereal.