How to fuel for sub-3: from training block to race day

Running a sub-3 marathon is about far more than logging miles. Training gets you fit but fuelling is what allows you to get the most from that training and to perform on race day. Every runner who has missed their goal by a few minutes knows the feeling: the legs seizing up, the stomach rebelling or the energy tank running dry at mile 22. These aren’t just bad-luck moments. They are often preventable with the right approach to nutrition. The good news is that you don’t need to become a sports scientist to get this right. You need a simple consistent strategy, tested in training, executed calmly and supported by sensible choices before and after the race.

During the training block

Think of your daily nutrition as the foundation for all the work you are doing. You need enough carbohydrate to fuel the miles and enough protein to repair the damage and come back stronger. If you under-eat your body will let you know through fatigue, soreness or stubborn niggles.

• Protein target: Most sub-3 runners should be looking to eat a solid serving of protein after their runs and again before bed. A whey shake in milk within 20 minutes of finishing, salmon with rice and greens at dinner or 200 g of Skyr before sleep are good examples. It’s not about bulking up, it’s about holding on to muscle and recovering well enough to hit the next day’s run.
• Carb habits: Carbohydrates should be your training fuel. Oats with banana and honey before a long run, white bagels with jam mid-morning or pasta with a simple tomato sauce in the evening all do the job. The big mistake is to let glycogen stores run low without meaning to, especially before long runs or intervals.
• Body-comp timing: If you need to lose weight do it before or after the block, not during. Running 100–160 km a week while also restricting calories is a recipe for injury and burnout. The mileage itself will reshape your body, trust the process.

Supplements can play a role. Caffeine, creatine, beetroot juice, beta-alanine and sodium bicarbonate are the ones with the most evidence. You don’t need to use them all and they are no substitute for good food. But used carefully and tested in training they can offer small but real advantages.

Pre-race prep

The last few days before the marathon are about topping up, not overloading. Carb-loading works but it doesn’t mean stuffing yourself to the point of discomfort.

• Carb-load smart: Two to three days of simple carbs like white rice, pasta, potatoes, oats and bread. Think full but not bloated. You want to start the race feeling light and stocked, not heavy and sluggish.
• Race-morning breakfast: Eat something familiar 2–3 hours before the start. Aim for a decent dose of carbs from easy-to-digest foods. White bagels with jam, porridge with syrup, pancakes with honey or toast with banana are tried-and-tested choices. Keep fat and fibre low so your stomach isn’t working overtime.
• Caffeine: If you use it, stick to a dose that works for you, whether that’s strong coffee, a caffeine gel or both. The key is to know how your body reacts.

Above all, nothing new on race day. If you haven’t tested it in training don’t gamble on it now.

Race-day fuelling and hydration

The marathon is an eating and drinking contest as much as it is a running one. The wall isn’t fate, it’s glycogen depletion. And you can avoid it.

• How much to take: Start fuelling early well before you feel empty. Aim for a gel every 20–30 minutes or a combination of gels and energy drink. That’s around 40–60 g of carbs per hour for most runners, rising toward 90 g only if you’ve trained your gut to handle it. Practise this rhythm on long runs until it feels automatic.
• Hydration that helps: Take small sips regularly. Carry a 250 ml soft flask or use the aid stations smartly. Even mild dehydration can cost you minutes. Electrolytes can help, especially if you’re prone to cramp or racing in the heat.
• Caffeine during the race: Topping up mid-race can sharpen your focus when fatigue sets in. A caffeine gel every 7–8 km works well for many but only if you’ve practised it.
• Carrying your own: Don’t leave fuelling to chance. Aid stations can be crowded, chaotic or even empty by the time you arrive. A small belt or flask setup ensures you get exactly what you need when you need it.

Recovery

Recovery is not an afterthought. It’s the final stage of training, the moment your body absorbs all the work you’ve done.

• First 20–30 minutes: Get carbs and protein in quickly. Chocolate milk, a whey shake plus a banana or a bagel with jam and a yoghurt all work.
• Next few days: Keep protein high, scale calories gradually back as mileage drops and prioritise sleep. Build meals around lean proteins and carbs like chicken and rice, tuna and pasta, eggs on toast. Expect soreness to peak at 36–48 hours then ease.

A few swims, easy walks or gentle spins can help blood flow without adding strain. Recovery is about balance. Reward yourself but don’t let a celebration slide into weeks of lost fitness.

For more details about the first 24 hours, click here.

For more details about the first week, click here.

Nutrition and fuelling aren’t extras, they are central to going sub-3. During training it’s about eating enough to fuel and repair. In the final days it’s about stocking up calmly. On the day itself it’s about fuelling early and often, drinking steadily and carrying what you trust. Afterwards it’s about replenishing quickly and letting your body fully absorb the block you’ve just completed.

Think of this as part of the discipline. You’ve already put in the miles, the early mornings and the tough intervals. Now you give yourself the best chance of reaping the rewards. Get nutrition right and you’re not just running 42.2 km, you’re running with the confidence that nothing is left to chance. That is what it takes to run under three hours.