How to Fuel for a Half Ironman

While training will always be important, how you fuel your body before, during, and after a 70.3 race can have a huge impact on your success. Avoid the common mistakes and learn to fuel effectively with our comprehensive guide.

Carb loading, gut training, GI distress, eat more carbs, eat less carbs, refuel immediately post-workout…With so much “noise” out there when it comes to sports nutrition, it’s little wonder that many people get lost in the fueling labyrinth and just “snack and hope” during their daily triathlon training. But we’re here to help simplify some of the advice and give you some clear do’s and don’ts when it comes to fueling for optimal daily training as well as provide clear guidelines for race week, race day, and post-race. 

Avoid the Biggest Mistake of All

Scott Tindal is a sports nutritionist who’s worked with some of triathlon’s leading professional athletes as well as scores of age groupers. When it comes to making mistakes with fueling and sports nutrition, Tindal has seen them all—and then some. He says he can’t emphasize enough that nutrition and fueling shouldn’t be something you think about come race week. It should be something that’s as integral to your training as swim, bike, and run. 

“The biggest mistake I think athletes make is that they think about how they’ll fuel the week of their race, and they might think about what to eat on race morning, but really it’s got to start when you begin training for your 70.3. So if you’re doing a 12-week build into your race then let’s start thinking about nutrition as you begin that build. That’s what’s going to give you your best opportunity to have the best race of your life.”

While many athletes are keen to spend $10,000 on a new bike or $400 on carbon run shoes, Tindal says he sees so many who are plagued with GI complaints or nutrition-related problems that could easily have been avoided.  “While it’s cool to get all the new gear, all of that will be useless if you bonk or throw up on yourself.”

With that in mind, let’s dial in how to manage your day-to-day fueling.

The Day-to-Day Basics

Understanding your basic daily caloric requirements, also known as your resting metabolic rate (what your body needs before you factor in any physical activity/training), is an important first step. While there are a number of formulas to help you find that number, there are also online calculators like this one that can give you a baseline number. You can also visit a dietitian or sports nutritionist. To determine the approximate amount of macronutrients (protein, carbs, fats) you should be eating each day, you can use the following guidelines:

• Protein: 1.8-3g of protein per kilogram of bodyweight [or if using imperial then a good guide is 1lb of protein per lb of bodyweight, so a 150lb athlete should aim to eat 150g of protein per day]

• Fat: 1g of fat per kilogram of bodyweight [or if using imperial then divide weight by 2.2, so a 150lb athlete should aim to eat ~68g of fat per day]

• Carbohydrate: 3-5g of carbohydrate per kilogram of bodyweight [so a 150lb athlete should aim to eat ~200g-340g of carbs per day]

Note that all of the above can vary based on factors such as gender, age, height, and level of activity in your daily work. 

Tindal says: “The above guidelines do not include exercise. Based on your training and activity levels, that’s where you really start to nail it down as an athlete.”

The Golden Rules for Training

With your baseline numbers in hand for daily macronutrients and calories, now you can start to think about how to fuel for your training. Tindal has a few simple rules he has his athletes follow:

• For sessions shorter than 70 minutes in duration, no calories necessary, drink to thirst.

• For high-intensity sessions ~70 minutes or longer, take on 30-50g of carbs per hour.

• Anything over 70 minutes requires fueling. For lower intensity workouts (Z1, Z2), consider eating real foods such as sandwiches, boiled potatoes, trail mix, or anything that will give you a mix of carbs, protein, and fat.

• >2-hour ride: For women pushing more than 160 watts and men riding 210-220 watts and above, aim for 90g carbs/hour. 

• <2-hour ride: Aim for 50-60g carbs/hour.

Carbs Are Your Friend 

Carbohydrates have suffered an image problem in the triathlon world in recent times and, perhaps not unsurprisingly, in a community where so many are ripped and lean, it’s not uncommon to hear athletes brag about minimal fueling and/or low-carb diets in a bid to lose weight. It’s something Tindal believes is slowly getting stripped away, but the perils of underfueling can be far-reaching and pernicious.

“Whenever I hear an athlete say they smashed a two-hour ride on nothing but water I can’t help but think, ‘well, just imagine how much better you’d have felt if you’d have eaten some carbs on that ride’. I think that badge of honor is slowly getting stripped away.”

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He explains that inadequate total calorie intake can lead to susceptibility to low energy availability (LEA) and ultimately chronic low energy can move into RED-S, (relative energy deficiency in sport). Especially when training for a race, many athletes can fall into the trap of prioritizing weight loss or chasing a certain body composition instead of focusing on training, which can often lead to more problems, particularly when it comes to training consistently.

“The problem many athletes face is creating a huge deficit between energy income and expenditure,” says Tindal. “After the first week they’ll be feeling terrible, after the second they’ll be in a hole, and after the third they’ll simply not want to do it any more.”

By being aware of your resting metabolic rate and fueling adequately for each workout, you can soon be well on your way to banking weeks of consistent training for your 70.3 race. 

Tindal says: “Focus on consistency. If you do things well, time and time again, you get results. Swim consistently. Ride your bike consistently. Run consistently. Eat well consistently. And you know what? You’ll start to see the scale shift in the direction you want it to go.”

It’s also important to think about the relationship between your daily nutrition (what you eat outside of training) and your fueling (what you eat prior to, during, and post-workout) as they are, of course, inextricably linked. Tindal refers to this as managing energy expenditure in-session (eating/drinking enough to adequately fuel your workouts) and then managing your energy intake outside of sessions. “When you need to eat in training, do not shy away from it,” he says. “I can guarantee the session will be 50 times better, as will your recovery and how you feel on a day-to-day basis.”And by doing this in-session, it’ll be far easier to make the right choices in your daily nutrition.

So now you know how best to fuel your 70.3 training build, what happens in race week?

Race Week Fueling

Welcome to race week. The hard work is done, all that’s left now is to reach the start line feeling fresh, well fueled, and ready to go. So what does that look like from a nutrition point of view? 

The short answer is: Absolutely nothing new and absolutely everything you’ve been doing in training up until this point (assuming it’s been working, that is). 

Some simple rules apply: Don’t try to lose weight during the 10-14 days pre-race. You should be aiming for “maintenance calories” of 4-7g of carbs per kilogram of bodyweight . This is not the time to try a new approach to fueling. It’s the perfect  time to continue doing what you’ve been doing day in, day out, in training. 

While carb loading is certainly not a new phenomenon, there are new and improved ways to approach it. “Simply eating a huge bowl of pasta the night before the race isn’t it,” says Tindal. 

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Instead, he advises steadily increasing the amount of carbs you’re consuming two days out from the race, aiming for about 6g of carbs per kilogram of bodyweight. And once you hit 24 hours to go, that’s when you should look to consume ~8g of carbs per kilogram of bodyweight. So for a 150lb athlete, that’s approximately 550g of carbs. For some of the elite athletes he works with, this number could be as high as 10-12g of carbs per kilogram of bodyweight. (But you shouldn’t attempt this unless you’ve trained your gut to cope with this amount of carbs).

Other key rules? Reduce the amount of fiber you’re eating, no more than 10-15g per day ideally. Also stick to ultra-processed foods with a high glycemic index like cereals, white rice, white bread, fruit, and whatever carb drink you’ll be using in the race. 

“Don’t be afraid of eating the same foods over and over, and keep your protein and fat intake consistent,” Tindal says. “You can reduce protein and fats slightly from where they might typically be.”

A typical day’s food could look like: 

• Breakfast: Yogurt, fruit, sweet white rice [boiled rice with protein milk and 2-3 tbsps of maple syrup]

• Snack: White toast and jam + carbs drink [80-100g carbs in 1-liter of fluid]

• Lunch: Chicken and rice with sweet chili sauce, fruit

• Snack: Bagel with jam/honey

• Dinner: Chicken and pasta/rice, fruit

Tindal says: “A lot of people will comment on how boring this is, but it’s not supposed to be a culinary delight. You don’t race a 70.3 every week and you need to think about fueling with purpose. These are meals you should have tried and tested before key sessions too.”

The night before the race aim to finish dinner early as for most Ironman events you’ll be getting up early on race morning. Front-load your carb intake the day before the race so you’re not trying to consume it all the night before.

Race Morning

Many people struggle to eat much on race morning due to nerves, but it’s important you eat something, typically two to three hours before your race start time. It should be something you’ve eaten multiple times before key sessions so it’s all familiar—nothing new on race day!

Popular options include toast/bagel, jam, and banana, but if you’re looking for something with more substance then overnight oats are a go-to choice for many pros [oats soaked in milk, maple syrup, sometimes a scoop of protein powder]. You’re looking for 2-3g of carbs per kilogram of bodyweight.

About an hour before your race start you’ll want to “top up” with about 50-100g of carbs [sports drink or energy bar], and then at about 15 minutes pre-race start it’s a good idea to get in an energy gel, chews, or some liquid carbs (something that will provide 30-50g of carbs). From breakfast up until the race start it’s also a good idea to sip on either a bottle of electrolytes or plain water. 

In-Race Fueling: Bike

In-race fueling really begins on the bike and it’s advisable to only reach for your first calories once you’re settled on the bike after the swim and T1 (transition one), but certainly don’t leave it much longer than the first 15-20 minutes. Be sure to have everything set up logistically and well rehearsed from training so that you know where you’ll be storing all of your calories [bento box, cockpit hydration, gels/bars in race kit pockets, etc.].

RELATED: The Most Common Mistakes Tri Pros See Age Groupers Making

Tindal has athletes fueling differently based on the power output and carbohydrate tolerance, e.g., an athlete who has trained on 50g of carbs/hour will not suddenly aim to take on 100g of carbs/hour in-race.

“Depending on the athlete and their power output on the bike it’s going to range somewhere between 50g to 120g of carbs per hour,” he says.

Those riding 150-160 watts or less shouldn’t need more than 50-60g of carbs/hour, he advises, while those riding above that should be aiming for 60-120g, based on what they’ve successfully practiced in training. 

There are many fueling options, from energy gels, bars, and chews to high-carb drinks (or even real food), but really it comes down to what works for you and what you’ve tried and tested in training. (Note: this helps underscore the importance of working nutrition and fueling into your 12-week build from the very start). 

Many elite athletes will lean towards solid or semi-solid foods in the first half of the 70.3 bike but then switch to semi-solids or liquid/gels only in the latter half in anticipation of the upcoming half marathon.

In-Race Fueling: Run

Some of the best 70.3 and Ironman fueling advice I ever received was to think of the bike as a “buffet” for the run, because once you hit the run course it becomes infinitely harder to consume calories. Of course, some people do eat or drink in T2 (transition two) but if you’re racing for a podium or a PR you might prefer to grab gels/chews/calories that you have lined up next to your run shoes and simply get running. It’s a good idea to either carry your own fuel or to be familiar (and have trained) with what’s provided on course. 

Tindal’s recommendation for run fueling is one calorie per kilogram per kilometer, so for a 60kg athlete running a half marathon that’s approximately 2100 calories. If that seems high, remember that it’s not a problem to finish the race in a deficit, you just don’t want to accumulate too much of a deficit too early into the race.

“Most people will want to aim for 30-50g of carbs per hour,” says Tindal. “If you’re at the sharper end of the race then you’d be looking for more like 50-100g of carbs per hour, but again, that’s got to be something you’ve practiced otherwise it might not end well.”

Post-Race Fueling

Surely post-race fueling is simply burgers and beer, right? Well, yes and no. While it might feel amazing to eat and drink whatever your heart (or gut) desires, Tindal emphasizes that the key thing to do post-race is to consume a large volume of protein with a decent amount of carbs. 

“I usually recommend an athlete has a dry protein shake set up in their post-race bag,” he says. “If you can get 40-50g of protein in with some creatine and then just add milk or water on the finish line, plus eat a banana or two, it’s going to make a huge difference to your recovery in terms of being able to walk the next day.”

Aim to eat a proper meal with plenty of protein and carbs within one to two hours of finishing your race. And remember that you’ve just completed something very physically and mentally challenging that your body will need time to recuperate from over the coming days and weeks, so continue to eat and drink well to help expedite your recovery. Your body—and mind—will thank you for it.