Dr. Luke Powles | Clinical Director at Bupa Health Clinics
If you’ve ever stared down the barrel of a 26.2-mile slog or a triathlon swim-bike-run circus, you already know the truth: nutrition for marathons and triathlons can make or break your day. In fact, most seasoned racers will tell you that nutrition becomes just as important as miles logged or laps swum.
These events demand a level of energy output that would make a pack mule wince. From the first training block to the final, delirious stagger over the finish line, getting your fuel right isn’t optional—it’s survival. Eating smart helps you perform better, recover faster, and avoid the charming cocktail of injury, illness and “why did I sign up for this?” regret.
Listen To Your Body (It Knows When You’re Being Daft)
Running, cycling and swimming torch calories like a bonfire on a windy night. Your daily needs vary depending on age, gender and activity levels, but as a rough rule, women average around 2,000 calories and men around 2,500. Once you’re training for endurance, those numbers are about as useful as a chocolate wetsuit—you’ll need more.
Ultimately, one of the best things you can do is listen to your body. If you’re feeling hungry, make sure that you have something healthy to eat.
And if you’re exhausted or sore? “Likewise, if you’re in pain or are feeling tired, rest up to reduce your chance of injury.” No medal is worth limping through race week like a Victorian chimney sweep.
Carbs: Your Trusty Sidekick
You can’t talk nutrition without talking carbs. They’re the rocket fuel of endurance sport, giving you both immediate energy (glucose) and reserves (glycogen). Think pasta, rice, oats, wholemeal bread, milk—your body breaks them down into the good stuff.
Carbs keep you steady, keep you moving and, frankly, keep you from sitting on the kerb halfway through training wondering where it all went wrong.
Before You Head Out: Feed, But Don’t Sabotage Yourself
Good planning beats good intentions every time. Eat early enough to digest, especially if you’re setting off for more than 90 minutes.
Ideal pre-run snacks 30–60 minutes before:
- Banana
- Greek yoghurt with granola
Meals to eat two to three hours before:
- Wholegrain cereal or porridge with low-fat milk
- Jacket potato with tuna and salad
Avoid fatty or high-fibre meals unless you enjoy stomach roulette.
Hydration also begins before you lace up—steady sips through the day, and keep fruit juice and smoothies to the occasional 150ml glass.
During The Grind: Keep The Engine Ticking
Most people can cruise through a short workout without additional food. But once you hit the hour-plus mark, your body starts rummaging around for extra fuel.
For shorter efforts, water is fine. For longer ones, an isotonic drink helps replace lost sugars and salts without turning you into a sloshing water balloon.
Little and often is the trick. Gulping like you’ve crossed the Sahara is not.
After Your Session: The Recovery Window
Your post-workout fuel is where the magic happens. Carbohydrates refill depleted glycogen; protein repairs the muscle fibres you’ve just battered; fluids replace lost electrolytes.
Aim for a snack within 30 minutes:
- Banana
- Sports bar with carbs and protein
- Low-fat milk (excellent combo of carbs, protein and minerals)
Then, within two to four hours, sit down for a proper meal. A few no-nonsense options:
- Chicken with potatoes and steamed vegetables
- Vegetable chilli with rice
- Noodle stir-fry with prawns and vegetables
There Is No One-Size-Fits-All Plan
What works for your training partner might leave you bloated, ravenous or ready to nap under a park bench. Experiment with timing, snacks and meals during training—not on race day.
As the guidance notes: “You may find that certain foods or eating at particular times works better for you.”
Dial in the routine now, and you’ll go into race day with a plan instead of a prayer.
