Calories in v calories out - the equation

Calories in v calories out - the equation

How much should I eat during a marathon? How many calories will I burn in an Ironman? How much food do I need for my long ride? These are the most common questions in endurance nutrition but they all hide one big trap - the calories burned v calories consumed equation will never balance

As long as you don't try and balance the equation, all will be well. But it's such an easy trap to fall into and we've all done it. Even experienced athletes racing a new distance for the first time, or entering a new type of race can fall prey to the mistake. 

Food is comfort, food is security, and when the landscape around your sport or event shifts to become unfamiliar as it does when you take on a new challenge, the temptation to fall back on calories as a safety blanket can be strong. 

Don't fall for it. It will slow you down and could wreck your race.

Calories in v calories out: logically perfect, practically terrible

Logically it makes perfect sense. 

You're working harder as an athlete, so you're burning more calories. If you can just find out how many you'll burn and eat that much, you'll be sorted. 

The average marathon runner around the 4-hour mark will be burning 800 calories an hour for a total of 3,200 at the end of the race. 

Ironman competitors burn anything from 7-10,000 calories covering their 140.6 miles.

calories in v calories out - how many calories do i need for an ironman?

Burning calories in triathlon = good. Trying to stuff them all back in during the race = bad

So it stands to reason all of those calories burned need replacing right? 

And they need replacing as they're being burned otherwise you'll be out of energy and you'll grind to a halt. Just like a car with an empty fuel tank. 

Duh, anyone can see that. 

So let's look at our marathon runner, burning 3,200 calories:

Energy gels contain around 90 calories each. Replacing all calories burned while running would require 35 gels, or one every seven minutes. As a comparison, 3,200 calories is six Big Macs...


Houston, we have a problem. 

You couldn't eat close to that much sitting down for a meal at your absolute hungriest, let alone while running a marathon. 

In Ironman the situation gets even crazier:

10,000 calories? Well, that's 111 energy gels. In Big Macs, we're talking 18.

Balancing the equation will never work.

Stored fat: the key to balancing the equation

The reason we don't even need to try and balance the calories in v calories out equation is stored fat. 

Even in a lean body stored body fat holds enough energy to power us for literally days on end. Stored fat takes up the slack in any calorie deficit situation during exercise. 

The Holy Grail for all endurance athletes is to optimise their fat-burning base (the exercise level below which they are primarily burning stored fat for energy). The more they are able to access stored fat as fuel, the fewer calories they need to replace while racing, the less food they need to digest on the move, and the more stable their energy levels are. 

Achieving this can be done through simple dietary and training adjustments.

Add to this the fact that mood levels track energy levels, and you can see why a stable energy base throughout your endurance event becomes even more important. 

With stable energy not only are you racing faster and easier, you're also racing happier. 

And with the mental side so key to endurance performance a happier athlete will always outperform one rollercoasting through an exhausting loop of mental peaks and troughs.

This is why at 33Fuel all of our nutrition products promote optimum fat burning by delivering powerful good fats, while also letting you perfect the stable energy trick by balancing those good fats and other high quality athletic nutrients with natural, low-GI sugars for the gentle flow of carbs you need. All without any of the nasty energy spikes/drops you may have experienced with other products. 

calories in calories out 33shake pure endurance bundle

Our bestselling 33Fuel Pure Endurance Bundle packs all the extra nutrition you need for that serious training block or race. As one of our awesome customers explains: "I used these products for the UTMB [a 103-mile non-stop mountain ultramarathon] and they worked perfectly. I've always struggled with a dodgy stomach in ultras and have since found real, whole foods work best compared to all the other crappy sports nutrition" 

Calories in v calories out: making it work on race day

We know the simple lesson is you never need to balance the equation - your body has it covered. Fueling to hunger and not to schedule during your racing and training is the ultimate key to success.

While this all makes perfect sense now, things can feel very different in the emotionally-charged atmosphere of race day. 

Here the temptation to eat more than you truly need can be overpowering - other sports nutrition companies have bought so much science 'proving' insane consumption levels are necessary it's still a very easy line to fall for. 

Truth is all these scheduled plans do is force athletes to overeat and underperform.

Sadly far too many sports nutrition companies keep pushing this heavy consumption message despite very clear real world evidence it doesn't work because it makes them a lot of money.

As far as we're concerned at 33Fuel, the sellout nutritionists legitimising this hogwash should all be made to run a marathon while forcing down a gel every 15-20 minutes and see how they enjoy it. 

To learn more on fueling to hunger and nailing race day fueling, you'll enjoy our post on how to develop the perfect fueling strategy for any race, at any distance, and in any conditions. Be warned though, images here are a little graphic so this one is best not read while eating.

And should you suddenly feel the need to pack an extra stash of gels 'just in case', remember it's most likely that you need less sports nutrition than you think

Calories in v calories out: timing matters

The last takeaway here is timing. 

Because while balancing the calorie equation on the day is nuts, over the longterm it will need balancing.

Not exactly, and not in an exact timeframe either. But having burned several thousand calories exercising and having drained our carb stores while also taking a big chunk of our stored fat supplies out, as performance-minded folks we need to be conscious of the need to refill the tank, and to do it with the best quality nutrition. 

This is what powers our recovery, brings us back stronger and lets us keep loving our sport while performing at our best. 

great daily diet has you covered here. Focus on whole foods, go big on fruits, veg, nuts and seeds and drink plenty of water. Snack, graze, fill your face, enjoy and remember to keep it real - 10% of the time eat what the heck you like.

how much should i eat during a marathon - calories in v calories out

Focus on powerful whole foods in your diet, drink tons of water and this will cover the majority of your rebuilding and pre-fueling needs. Keeping it real matters too, so 10% of the time bin all rules and eat what the heck you like. Cheers!


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