The Importance of Marathon Training Nutrition - Why Your Marathon Diet Makes or Breaks Your Race

Marathon training nutrition comes down to eating enough — mostly carbohydrates, with steady protein for muscle repair and some good fats — and practising your race-day fuelling long before race day. Below: how to calculate your carb and protein targets, why dieting during marathon training backfires, how to fuel right after a workout, and the carb-loading and race-day rules that keep your stomach and your legs on your side.

Skip a page like this once and you'll find out the hard way — usually somewhere past mile 20, when the wheels come off because you under-fuelled for months without realising it. Good nutrition is the difference between a race you're proud of and one you'd rather forget. When we're training for a marathon, we need meaningfully more calories than non-runners, and the mix matters just as much as the amount.

Marathon Training Nutrition Tip #1: Don't Ignore Your Carbohydrates

The best marathon diet concentrates on carbohydrates. Once carbohydrates enter the body, they are absorbed as muscle glycogen.

We tap into this glycogen for fuel and energy-replenishment.

Carbohydrates appear in many foods, but concentrate on whole grains, fruits, vegetables, and low-fat dairy products — these give you the most nutritious carbohydrates.

Work out your daily carb target in grams by multiplying your weight in pounds by 3.2, or your weight in kilograms by 7.

That gives you the total grams of carbohydrates to aim for each day.

I wouldn't recommend going into painstaking detail trying to match those exact measurements every single day. But do keep in mind that great marathon nutrition means plenty of whole grains, fruit, vegetables and low-fat dairy products. Each day, every day.

Marathon Training Nutrition Tip #2: Protein for Muscle Repair

Secondly, centre your marathon nutrition on protein. It's a myth that protein alone builds muscular bulk, but it is absolutely necessary for muscle growth and repair.

This matters especially during marathon training and other high-exertion activities that cause muscular wear and tear.

Include protein in every meal. Make that a non-negotiable.

Good protein sources include lean meat, fish, eggs, poultry, and low-fat dairy products. Tofu, nuts, and dried beans work well too.

To find your daily protein intake, multiply your weight in pounds by 0.6 or your weight in kilograms by 1.3 — that's the number of protein grams to eat each day. Spread that across 3–5 servings per day.

Marathon Training Nutrition Tip #3: Eat the "Good" Fat, Avoid the "Bad" Fat

To round out your daily marathon training diet, eat a small amount of "good" fat.

Stick to sources containing unsaturated fat rather than artery-clogging saturated fat. Olive oil, nuts, and salmon are good examples of unsaturated fats.


So, in summary, the above three marathon diet tips are simply the foundations of a healthy diet.

I've probably not told you anything new here — but we have to start with the basics.

You can get your marathon nutrition right by staying away from products high in sugar, deep-fried foods, and heavily processed foods including many frozen meals.

This isn't incredibly hard. You know what's healthy and what isn't.

A sensible approach to a better marathon training diet follows two basic rules:

Make sure each meal covers carbohydrates, protein and good fats.

Focus on small, sustainable changes. Not getting enough protein right now? Fix that first. Make sure each meal has some protein in it over the next two weeks. Once that's a habit, move on to the next thing.

The gradual small changes are more effective than a complete overhaul in one big go. That's my experience, at any rate.

Marathon Training Nutrition Tip #4: What About Supplements?

I'll be honest — I'm not a huge fan of supplements.

Unless they work. Then I really love them.

In principle, a healthy diet gives you all the nutrients you need in normal daily life.

But training for a marathon is not normal daily life. It's a lot of hard work.

You will be more tired during the period you're training for your marathon. Guaranteed.

More sleep helps — and sleep should be an absolute priority for you. But nowadays it's hard for almost everyone to get enough. Work, children, career — it can all get in the way of proper rest and sometimes even of eating well.

So, which supplements are worth considering? I'm not a doctor — and I'll leave it there. But I've had good personal experience with magnesium to ease stress and muscle pains.

Beyond that, I'd base any supplements on your blood test results. I take vitamin D regularly. My doctor found my levels a little low in winter — which surprised me, given that I live in Australia. But I'm in Victoria, and winters here are cold, wet, and distinctly short on bright sunny days. So vitamin D is a priority for me in winter only.

I'd recommend getting some detailed bloodwork done. Marathon training is incredibly hard work, and when you're putting your body through that level of stress, every little bit helps.

I've seen remarkable changes in people who had certain deficiencies — iron deficiency being the most striking example. My wife has had a history of low iron, and after a recent iron injection she felt an almost instant and very significant lift in energy levels. Get your bloodwork done. Make sure you're on the right track.

Marathon Training Nutrition Tip #5: Dieting During Training Is a No-No

I'd be very cautious about combining a low-calorie marathon diet with marathon training. When you're logging all those miles, you need to eat enough to support the work.


Try to starve yourself and you'll run out of fuel. You might lose a little weight, but the consequences are severe — very low energy, a much higher likelihood of skipping workouts, mounting irritability, and a real risk of getting sick.

When you're training for a marathon and running all those training miles, eat enough to support your training.

You'll likely lose a bit of weight over the course of a marathon build-up anyway. But weight loss should not be your goal during marathon training. Don't deprive your body of what it needs.

Eat healthily, and eat enough to sustain your training.

Marathon Training Nutrition Tip #6: Eat Directly After a Workout

Eat directly after a workout. This is probably one of the more important points on this page. Your body is most receptive to taking in nutrition directly after a workout — don't waste that window.

Choose a snack or meal that is high in both carbs and protein. Diet drinks are fairly popular as a quick option because they offer a good carb/protein ratio.

But I prefer natural choices for my marathon nutrition — something like a sandwich with lean meat or salmon, green leaves, tomato and cucumber. Or some noodles with tofu and stir-fried vegetables. Quick to prepare, healthy, and exactly what your marathon training diet calls for.

Also consider an extra, healthy snack at night. When you sleep, you go through an extended period without nutrition. When you're deep in marathon training, your body can do with a bit of extra care at that point.

I generally eat three meals a day and three snacks — mid-morning, mid-afternoon, and sometime after dinner — when I'm doing higher mileage training. The combination of running and strength training really requires regular fuelling. Otherwise I get hungry and very low on energy.

Marathon Training Nutrition Tip #7: Practise Running and Eating and Drinking

During the marathon you'll be eating, drinking and running all at the same time. It's not as easy as it sounds. Practise it during training.

Many of us rely on energy gels and sports drinks as our marathon diet on race day. A good energy gel can do wonders — but you need it to be not too gooey, so test them during training. Taste matters enormously to me. There are certain ones I love and some I can't stand. There's a salted caramel one and a vanilla one I rate highly, but a coffee-flavoured one is dreadful for me — and I love coffee. It's genuinely trial and error. Work out which ones you like well before race day.

Some runners prefer more natural alternatives — banana, dates, sultanas/raisins, trail mix, and so on. I find crunchy, chewy things hard to manage mid-run, so I generally stick to gels and chews.


I take a hydration pack on long runs. It lets me carry small water bottles and has pouches for gels, trail mix and so on.

While running — and this does take a bit of practice — you can open the pouch, grab a gel, take it in, and wash it down with water.

My advice: take a gel slowly. I'll happily take half a mile or more to finish one. It stops you ending up with a mouthful of gooey substance all at once, and I find it easier to digest that way too.

Eat at regular intervals and start eating early in a run — something like every 30 minutes. In the early stages you won't feel hungry, but by the time you feel hungry, it's too late.

It takes a while for food to reach your blood — often 15–30 minutes, and even longer during hard efforts as blood gets diverted away from your gut — so eat before you think you need it.

Same with water. Start drinking from the beginning. Small sips every 15–30 minutes works well.

I prefer to eat and drink based on the clock — pick a regular interval and stick to it regardless of how I'm feeling — rather than waiting until my body signals that it needs something.

Marathon Training Nutrition Tip #8: Carb Loading

One practice you may have heard about is "carb loading" or "carbo loading". Put simply, this means adding extra carbohydrates to your marathon diet in the days before your marathon. This fills your muscles with extra glycogen.

The goal is that when you run your marathon, your muscles will have top levels of glycogen — which keeps you going for longer.

A common misconception with carbo loading is that you first need to deprive yourself of carbs. The original practice from a few decades ago was that elite marathon runners would go out on long runs about 7–10 days before the race.

Afterwards they would cut out all carbs entirely. Steve Moneghetti, the great Australian marathoner, once said that this made him feel like "death warmed up." Not a great feeling. :)

After 3–4 days of that, they would then load up on carbs.

This was believed to be the way to achieve maximum glycogen levels just before the race.

It simply isn't true. Later research with more advanced technology showed that you absolutely don't need to deprive yourself of carbs. Just eat extra in the 2–3 days before the race. That's why pasta is such a favourite with marathon runners, and why all the big marathons now hold a pasta party the night before.

As a concrete target, aim for around 8–12 grams of carbohydrate per kilogram of bodyweight per day during that loading window. For a 65kg runner that's roughly 520–780g of carbs a day — considerably more pasta, rice and bread than you'd normally eat — so plan your meals accordingly.

Marathon Training Nutrition Tip #9: Don't Attend the Pasta Party (or the Expo)

This may come as a surprise. I've just told you to carb load, and now I'm telling you to skip the pasta party.

The reason has nothing to do with nutrition. Pasta the night before a marathon is a sound choice. But if you can avoid the pasta party itself, do so.

Most big marathons have a marathon expo with all kinds of goodies and discounts on running kit. Skip that one too.

Why?

Stay off your feet in the day or two before the marathon. That's the rule.

Don't go to bed late either.


Pasta parties are often great get-togethers.

But when they're poorly organised or simply very busy, you'll stand in a long queue waiting for your food.

You'll get talking to other runners, time will fly, and before you know it you'll be up too late.

After a top marathon performance? Then I'd highly recommend being non-social in the last day or two before the marathon — make your own pasta at home, or have a quiet pasta meal at a relaxed Italian restaurant, early in the evening, and then get to bed.

A bit of discipline and planning here can make a real difference.

I also recommend checking out my marathon taper page, which features a complete guide on tapering, including the 10 Don'ts of Marathon Tapering.

Marathon Training Nutrition Tip #10: Don't Experiment on Race Day

One of the biggest mistakes runners make is doing something completely different on race day. I'm not sure what drives it, but suddenly you get a bright idea and throw your entire marathon training diet out of the window.

Perhaps you've been talking to a friend in the build-up who swears by product X or drink Y and tells you, "You need this stuff on race day."

So you experiment with a different brand of sports drink or a food that somebody else loves.

Don't. Don't deviate from your marathon training diet on race day.

You've trained with a certain sports drink or water and with certain foods or gels. You've tested what works. Don't throw that away with a last-minute experiment.

It can end badly — stomach cramps, not being able to keep your food down, and worse. I've seen it all. Don't play around.


In conclusion, your marathon training diet comes down to eating healthily and making smart choices.

Marathon training is tough, so you need to eat well. And you need to eat a lot. Eat enough. Train smart. Use your training to experiment with what works for you on the run.

Once you've found a formula that works, stick with it — and especially don't change a thing on race day.

I hope these marathon nutrition tips have helped and that you head to your big race well prepared.

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