Triathlon Nutrition: How to Fuel the Swim, Bike, Run and Transitions

Triathlon nutrition is a puzzle. You have three disciplines, two transitions, and only one leg where eating is actually easy. Get your fuelling right and you'll start the run with energy to spare. Get it wrong and the run is where you pay for it.

Whether you're lining up for a sprint or building toward a long-course race in the Southern Lakes and beyond, here's how to fuel each stage, including the transitions most athletes forget to plan.

You can't eat during the swim, and the run is too bumpy to take on much. The bike is your main fuelling window. Fuel well there and you'll start the run with stable blood glucose and a settled stomach.

These are broad guidelines. Your body size, pace and conditions will all shift them:

• Sprint (around 1 to 1.5 hours): 30-60g of carbohydrate per hour, mostly on the bike
• Olympic (around 2 to 3 hours): Around 60g per hour, building toward 90g if your gut is well trained
• Half and full distance: 60-90g+ per hour

Start counting from the bike, since that's where you'll actually be eating. For more on carb targets, see our guide to on the go nutrition for endurance races. If you're training for a half or full distance race, our guide to fuelling 5-10 hour bike rides goes deeper on the bike leg.

• 2 to 3 hours out: Have a familiar, carb-rich meal that's low in fibre and fat, like porridge with banana, toast with jam, or rice.
• 15 to 30 minutes out: If it suits you, top up with a GU Energy Gel or a few GU Energy Chews and a few sips of water.
• Start hydrated: Stir an electrolyte drink into your morning, especially if it's going to be warm. Pure Electrolyte Hydration sachets are easy to pack in a race bag.

There's nothing to plan here. Anything you swallow in the water will be lake or sea, so keep your pre-swim fuel simple and save the eating for the bike.

T1 isn't a feeding stop. The goal is to have nothing to think about, so get set up before the race:

• Load your bottles into your cages in advance
• Tape gels to your top tube, or stash them in a frame bag or tri suit pocket
• Keep your hands free for your wetsuit, helmet and shoes

Once you're rolling, take a few sips of water, settle into position, then start your fuelling plan.

This is where the race is fuelled.

• Start early. Begin refuelling within the first 30 to 45 minutes rather than waiting for hunger.
• Use a timer. Set your watch to beep every 20 to 30 minutes as a reminder to take half a gel or 2 to 3 chews.
• Mix it up. Carry a couple of different gels, such as the Pure Fluid Energy Gel and BeeFast Energy Gel, alongside Clif Bloks, which are easy to grab from a top tube bag. On a half or full distance, a Clif Bar or a GU Energy Stroopwafel early in the ride adds variety and helps with taste fatigue.
• Sip steadily. Regular small sips beat occasional big gulps. In warm conditions, drop a GU Hydration Drink Tab into your bottle to replace what you're sweating out.
• Ease off late. Take your last proper fuel 15 to 20 minutes before the end of the bike so it's digesting before you run. After that, stick to sips and avoid big solids.

T2 is where plans fall apart. Your legs are shifting from pedalling to running, and your stomach is going from a compressed aero position to a lot of bouncing. Both take a few minutes to adjust.

• Stash your run fuel in advance. Put gels or chews in your run belt, tri suit pockets or a small bag racked at your transition spot, so you aren't relying on aid stations.
• Don't eat in T2 itself. Get moving first. Take your first gel or chews in the opening kilometre, once your breathing has settled.
• Always take gels with water. Concentrated carbs with no fluid is a common recipe for an upset stomach.
• Check your race briefing. Rules on outside support, aid station zones and litter vary between events.

Your gut has less capacity when you're running, so aim for smaller, more frequent doses.

• Most athletes do well on 30-60g per hour on the run, even if they took on more on the bike
• Half a gel every 20 minutes works well, as do a few GU Energy Chews every 15 to 20 minutes, which are easier to eat on the move than a full gel
• On a hot run, Saltstick Fastchews are a quick way to top up electrolytes if you're prone to cramping
• Use aid stations to wash fuel down, and find out in advance what will be on course
• If sweet foods start to turn your stomach, switch to a diluted drink and keep sipping
• If you'd rather carry your own fluids, a running flask keeps things simple
• If you use caffeine, save it for the second half of the race. Some gel flavours and drink tabs contain it, so check the label

A starting point for the bike, aiming for around 60-75g of carbs per hour. Check the labels on your own products to get the numbers right.

• One gel, taken in two halves
• One serve of chews
• A few Clif Bloks or a bar bite to fill the gap
• An electrolyte drink in your bottle, sipped across the hour

On the run, drop to half a gel every 20 minutes with water at each aid station.

Never try new nutrition on race day. Brick sessions (bike straight into run) are the best way to test your plan, because they let you rehearse:

• Eating on the bike at race pace
• Pulling fuel from your pocket or belt while running
• Starting the run with a full stomach from the ride

Practise your transitions too. The more automatic T2 feels, the less likely you are to skip your fuel when you're tired.

What should I eat during a triathlon?
Mostly carbohydrates, taken on the bike. A mix of drink, gels, chews and bars works best, then smaller, more frequent doses on the run.

How many carbs per hour do I need?
Around 30-60g per hour for shorter races, and 60-90g+ for races over two hours. Practise in training to find what your gut tolerates.

Should I eat in transition?
Not really. Use T1 and T2 to get set up and moving, and take your fuel just after, once you're settled.

What should I eat before a triathlon?
A familiar, carb-rich, low-fibre meal 2 to 3 hours before, plus an optional gel or a few chews 15 to 30 minutes before the start.

Triathlon nutrition comes down to a plan for each leg, fuel you can reach without thinking, and a gut that's been trained to cope. Start simple and test it in training.

Not sure where to start? Our team is always happy to help you build a plan. Browse our full range of nutrition gels, chews, blocks and bars in store or online.