What to eat before a half marathon
If you’re wondering what to eat before running a half marathon, you’re in the right place. I’ve done 2 half marathons (the Telford one and one in Birmingham, UK) and so I remember what it’s like trying to plan your food and nutrition before you run a half marathon.
So let’s break it down a bit.
Does it matter what you eat weeks before a half marathon?
Elite athletes would probably train differently to how I did; their running coaches will have them eating very specific meals weeks in advance, I’d expect.
Also, if you’ve trained and been running ahead of your half marathon to your limit, there’s potentially no benefit to training your body (in terms of your race performance and time) changing your diet 3-4 weeks before. That’s the opinion of my dad, who’s run multiple half marathons and marathons too.
And I completely agree. If you’ve been training to run a half marathon for months on end, and you’re in reasonably strong shape for your race, suddenly having extra carbs for 3 weeks won’t really have an impact – specifically on your finish time.
Of course… You might feel like psychologically better because you’ve been eating better. But if you’re trying to work out a nutrition plan pre half marathon, I’d not worry too much about eating a ‘half marathon diet’ or anything like that 3-4 weeks before the big day.
Adjusting your food planning for the half marathon day
The one thing I would say is that it’s worth planning ahead for when you’ll eat before and on half marathon day. For example, let’s say you’ve been training hard getting up at 6am to eat your bagel and banana and run your miles. Maybe that’s working well for you around your 9-5 job.
But if you then realize your half marathon is at 2pm, your body isn’t trained for that food schedule. And that affects your sleep too because you might be more tired in the early afternoon (and you’re usually running on endorphins at 9-11am), you see?
So it’s worth thinking ahead once you’ve booked your place on your half marathon to make sure your body, sleep and digestion systems are all prepared for the day from a timeline perspective.
What to eat the day before a half marathon
So what should you eat the before a half marathon? A lot of health and running magazines will have a full, specific breakdown of the best foods to eat before a half marathon. And of course, the big majority of those resources are crafted by extremely professional, knowledgeable and often highly qualified health writers.
But I would say, don’t change your pre half marathon diet just because a magazine says it.
For example, my marathon runner dad remembers years ago when…
“the theories back in the day were different”
Starve yourself of carbs (body goes mad to store)
Eating after the run – recovery (natural sugars – fructose and fruit juices) back into your system so your body recovers quickly.
What to eat before a half marathon
Carbohydrates:
- Wholegrain pasta
- Brown rice
- Quinoa or beans
Protein:
- Chicken
- Fish like salmon or tuna
Healthy fats:
- Nuts and seeds
- Drizzle olive oil on your meal or include salmon
- Incorporate avocado
SMASH! This is something I learnt from a nutrition course. SMASH stands for:
- Salmon
- Mackerel
- Anchovies
- Sardines
- Herring
They’re all great for those oily fish types that are high in healthy fats (not the bad greasy ones), and also omega 3 (great if you have eczema like me).
What to eat the night before your half marathon
Breakfast choices
I’d not run a half marathon on empty for sure! I’d have a bagel with a banana and some honey and some fluid, not coffee.
What to eat during your race
Gels in sachets are very popular options.. and I think I’ve tried a few running gels years ago when I first started running. But really, they’re just sugar. My dad and I have always just stuck to sweets, like tTngfastsics, and they work perfectly fine!
You can even make your own electrolytes especially for hot, long runs.
Best advice for pre half marathon energy
If you’re planning your half marathon nutrition, my plan was to carb up the night before, and then have my Tangfastics before I run. That way, it stops my body going to use my slow burn carbs first.
I don’t drink coffee, but I remember having a cup of caffeinated tea. I don’t know if there’s a scientific reason whether caffeine affects your half marathon nutrition,.
But having my normal warm drink just helped me feel more switched on and I think that made me race better than if I’d felt half asleep. Maybe that’s caffeine.. Maybe it’s psychological. But that’s what I drink if it’s a morning half marathon.
I imagine a cup of coffee might make you go to the loo earlier – but you should be anyway if you’re properly hydrated.
What to eat after you finish your half marathon
After your half marathon, you want to grab some sugar to get energy back up. I used to grab a Mars bar or something like that. It’s why they offer you a goodie bag after you cross the finish line. They’ll throw in gels (often from the race partners etc), but dig deep and look for the energy snacks and.
Try and re-hydrate and get back to eating normally a little bit after you’ve finished your half marathon.
After I finish a long run of over an hour (so definitely for a half marathon!), I tend to be running on the runner’s high, get thirsty first, and then the appetite for a proper meal comes a little bit after; sometimes a good hour or so (longer if I’ve over done the run!)
My top tips for your pre half marathon nutrition
1. Don’t do something different on race day compared to in training
I’ve been there! Don’t get tempted to try eating something different on the day of your race. Do what your body is used to. You’ve trained for this (diet, running, mindset, all of it). Your body knows what to expect. Don’t throw it off with an “Oh I might just have a bowl of cheerios” or “actually I’ll skip breakfast today”.
2. Avoid greasy or fatty foods
It goes without saying a dirty fry up probably isn’t the best food to eat before a half marathon. The reason being, it won’t sit well in your system! You’ll likely feel very sluggish, and the last thing you’ll want to do is run a half marathon.
Stick to what you’ve been training for. Use the nutrition tips above that worked for me.
3. Check the weather forecast
Now you’re not going to eat the rain. But the weather is something to consider for sure. Yes for outfit reasons, but actually for the temperature. If you know you’re going to be running a half marathon in the peak of summer, you may want to consider adding electrolytes into your training – again, early on in your training, not the day of.
You’ll sweat more if it’s warm (obviously), but that means your fluid levels need looking after as you embark on the 13.1 miles. It’s not about what to eat before a half marathon. Drink is just as important, if not more!
4. Avoid high fibre foods (IBS trigger)
I have undiagnosed IBS and I’ve definitely had my fair share of IBS flareups. I would definitely avoid too many leeks or tonnes of broccoli the night before. And I’d make sure the day before I’d have my meals sensibly spread out; no super late evening meals with a massive portion size.
That would trigger my IBS. And with the pre half marathon nerves the next day, my gut will be going through enough stress! A good pasta based dish, like lasagna or tuna pasta with some light vegetables or salad, about 6-7pm the evening before; if it’s a morning race. That’s what I’ve done before.
Written by Katie McDonald, 9th October 2025
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