Triathlon Nutrition 101

An easy to understand, no-nonsense guide to triathlon nutrition…

As an online triathlon coach, one of the questions I’m most commonly asked is “which energy products should I use?”.

I can understand people’s confusion with triathlon nutrition because when I was a rookie triathlete I had no clue about nutrition either. I once did a Powerman Duathlon (10km run/60km bike/10km run) with nothing but a small bottle of Coke to get me through. By the halfway point I was so low on energy that I could barely cycle or run.

It was only after I did a University degree in Sports Science that I started to fully understand sports nutrition. I’m still no expert, but I certainly know more than I did before. It’s such a big and complex subject, so it’s no wonder that people find it hard to make the right choices.

With all that in mind, the idea behind this blog is to explain three key things:

1. The difference between fat and carbohydrate
2. What to eat before and during a race
3. The difference between energy gels, bars and drinks

1. The Difference Between Carbohydrate and Fat

During a triathlon, you’ll use two main types of fuel – carbohydrate and fat. Every decision you make about race-day nutrition will boil down to these two things.

Carbohydrates include a whole range of food types, from simple sugars like Coke all the way through to things like rice and pasta. Fats are found in a range of foods such as fish, butter, meat, avocado and olive oil.

Carbohydrates and fat both give you fuel, but not in the same way. Let me explain…

Phil’s Toyota Fuel Analogy

Imagine a Toyota Prius car. In case you don’t know, it’s one of those environmentally friendly “hybrid” cars that use both petrol AND electric power.

When you drive a Prius slowly around town, you’ll notice it’s the electric motor that does all the driving. However, when you get out on the open roads the petrol engine kicks in, powering you to faster speeds.

Well, your body is a bit like that Toyota Prius.

For all the slow stuff like long-distance cycling, you use more fat as fuel. And for higher intensities such as a 5km run race, you’ll use more carbohydrate.

That’s how our bodies work. Fat is our long-lasting, slow fuel. Whereas carbohydrate is our fast fuel that runs out quickly.

Our bodies know this. So for short, fast triathlons, you’ll use a higher ratio of carbohydrate versus fat.

On the other hand, for long triathlons or training sessions, you’ll use a greater ratio of fat to carbohydrate.

Still with me?

I remember my University nutrition lecturer telling us that the average human has enough stored body fat to walk 40,000 miles! I don’t know if that’s true, but I do know that we all have plenty enough fat to get us through an Ironman triathlon.

On the other hand, I know that our carbohydrate stores will run out after around 70 to 90 minutes of intense exercise. And therefore we need to supplement them during a race or a hard training session if we’re to perform at our best. Here’s how…

2. What To Eat Before And During A Race

The Evening Before

The evening before a race you’ll need to eat a carbohydrate-based dinner – something easy like pasta and sauce. Do not be tempted to eat lots of meat and vegetables, because the meat won’t provide any meaningful race fuel and the vegetables might give you stomach upsets when you run. Normally meat and vegetables are fine, just not right now.

Also, don’t eat more than usual, just your normal plateful is fine. Just a plate full of pasta and tomato sauce. No need for gluttony.

The Morning Before

On race morning, consume a carbohydrate-based breakfast 3-4 hours before the start, such as a big bowl of oatmeal porridge and honey, or three to four slices of toast. You could also sip a carbohydrate energy drink throughout the morning.

Personally, I eat three PowerBar Energize bars instead. It just saves me worrying about preparing breakfast. But that’s just me.

During The Event

What you consume during a triathlon depends on the event you’re doing.

If you’re racing a sprint triathlon, you don’t need much carbohydrate because it’s so short. You might benefit from sipping an energy drink on the bike and having a gel on the run.

For longer events, you’ll need to sip water regularly (particularly if you’re sweating a lot) and consume 40-70g of carbohydrate per hour. The bigger you are, the more you should consume within that 40-70g range. To give you some idea, 40g equates to two energy gels.

The best way to consume carbohydrate is little and often so that it’s more palatable. Try setting a countdown alarm to remind you every 10-minutes so that you don’t forget to eat in the excitement of the race.

Kickstart Your Training Today!
Choose from over 900 plans from 4-48 weeks long in beginner, intermediate, advanced, masters and off-season versions!

3. The Difference Between Energy Gels, Bars and Drinks

When it comes to triathlon nutrition, there’s nothing magic about energy drinks, bars and gels. Their main ingredients are carbohydrate and water, and you can normally make your own homemade versions. However, they do offer a convenient and well-packaged way to stay fuelled during a race.

Here are six common types:

Energy Gels

A sweet gel in a convenient packet, typically containing 100 calories and 22 grams of carbohydrate. Some contain salts, vitamins and caffeine, although the carbohydrate is the important bit. Gels labelled “isotonic” are more watery and easier to consume with a dry mouth but contain less carbohydrate per gram. Caffeine gels often taste bitter, but there are proven performance gains to be had.

Energy Drinks

Powdered or pre-made drinks containing predominantly water and carbohydrate. Some contain electrolytes (salts), vitamins, caffeine and even protein. Remember that on race day your main requirements are water and carbohydrate, although, for long races or hot days, electrolytes may prove beneficial. Most of the other magic ingredients (aside from caffeine) have no proven endurance performance benefit.

Energy Chews

These are simply chewy sweets or jelly blocks containing mostly carbohydrate. They are often more palatable than energy gels and don’t leave you with such sticky fingers. Personally, I use Clif Shot Bloks, as I enjoy them more than gels. One pack contains six blocks – the equivalent of two energy gels.

Recovery Drinks

The main ingredients in a recovery drink are carbohydrate and protein. Some also contain fat, electrolytes and vitamins. Research indicates that the optimal ratio for a post-endurance recovery drink is four parts carbohydrate and one part protein. Interestingly, plain milk contains a similar ratio. These drinks are convenient when you don’t have a chance to eat immediately after a tough workout.

Energy Bars

These are dense pre-packaged cereal bars, containing mainly carbohydrate. They are great on race morning or while training but can be difficult to digest during a short, fast race. Some bars have relatively high-fat contents, so read the labels first.

Recovery Bars

Tasty bars containing a mix of carbohydrate, fat and protein. These often taste as good as chocolate bars like Snickers and Mars, so it’s tempting to eat lots. Eating foods like these straight after exercise is shown to heighten recovery, although you could get the same effect from a homemade smoothie for example. Just be careful not to eat too many if you’re not training hard – triathlon nutrition never tasted so good.

That’s all for this fortnight folks. For more information on triathlon nutrition, check out my previous blog: 5 Triathlete Diet Tricks

Phil Mosley (Coach & Founder)
Phil Mosley (Coach & Founder)

Phil is a recognised endurance expert who founded MyProCoach in 2010 to offer smart training plans that still leave quality time for your family, friends & career - complete with highly-rated coach support (he has sold over 40,000 so far). Learn more here!

As featured on...

download (1)
220 triathlon

Popular Articles from the Training Tips Blog


Sign up for Phil's email newsletter!

Get expert training advice, the latest news and occasional discounts. You can unsubscribe at any time.

Kickstart Your Training Today!
Choose from over 900 plans from 4-48 weeks long in beginner, intermediate, advanced, masters and off-season versions!
Planning Your Off-Season

You can start our Off-Season (Fitness Maintenance) plans anytime you like.

They’re designed to help you maintain a good level of fitness when you’re not specifically targeting an event, such as, during the off-season, or anytime you’re taking a break from racing.

Planning For Your Event

For the best outcome, input the date for your “A” target race and the tool will default to a plan that will fill that gap nicely. If you want, you can then adjust the plan length to start it on a different day.

Note that you can still work in other, smaller races during your plan too!

The longer plans start easier and progress more gradually. This has a bearing on the difficulty level you choose. For example, a 12-week plan starts off at a higher level than a 36-week plan because with 12 weeks left there’s not as much opportunity to build up slowly.
Short Medium Long
4-12 weeks
14-24 weeks
27+ weeks
Required fitness level
Training phases
Fitness tests
Our Standard and Masters plans are designed to get you ready for your target event, while our Off-Season plans allow you to recover from a tough season but still maintain your well-earned fitness.
Approx. age
Under 40
Over 40
Recovery weeks
Every 4 weeks
Every 3 weeks
Strength sessions
1-2 per week
2 per week
1-2 per week
Likely goal
Train for event
Train for event
Maintain fitness
This table provides a brief overview of which level might be right for you, to help you get the most out of your plan. You should also note your current fitness levels and how many times you have done this event before.
Little to none
1-3 years
3+ years
Time to train
Likely goal
To finish
At least top half
All our plans are available either for sale directly on the TrainingPeaks Store (where you can also see screenshots of sample weeks), or you can subscribe as an Unlimited Athlete to be able to swap freely between all of them, among other benefits outlined below.
$24 to $159 per plan
From $24 per mth
Flexible, structured training
TrainingPeaks training app
Coaching videos, articles & FAQs
Email coach support

During plan only

Swap freely between all 900+ plans
Help setting up your training zones
Coach fortnightly engagement check
Discounted TrainingPeaks Premium (optional)
30-day moneyback guarantee
We're Sorry To See You Go!

Please confirm your cancellation below and one of our team will process it as soon as possible (stopping all future payments). Your subscription will still continue until the end of your current billing cycle (your “next payment date”) and there is nothing else you need to do.

Don’t worry, you will always be able to access your completed workouts and your TrainingPeaks login credentials will stay the same. Also, if any payments happen to come out before we cancel your subscription, we’ll simply refund them.