Trail Notes | Training Nutrition

Fuelling for

Female Ultra Runners

Fuelling is not separate from training. It is one of the skills that allows your body to adapt, recover and keep moving when the trail gets long.

There comes a point in ultra training where fitness alone is not enough.

You may have the kilometres in your legs. You may be building strength, consistency and confidence. But if you are not fuelling well, your body will eventually let you know.

Sometimes that looks like heavy legs halfway through a long run. Sometimes it feels like mood shifts, dizziness, gut issues, headaches, poor recovery, broken sleep or the sense that your body is working far harder than the pace suggests.

Why fuelling matters before you feel hungry

One of the biggest mistakes endurance runners make is waiting too long to eat.

In everyday life, hunger can be a useful signal. In ultra running, it often arrives too late. By the time you feel flat, foggy, emotional or depleted, your body may already be working from a deficit.

For long trail efforts, the goal is not to eat perfectly. The goal is to eat early enough, often enough and consistently enough that your energy does not have to fall off a cliff.

Fuelling is a female athlete issue

Female athletes are not simply smaller versions of male athletes. Energy availability, iron status, hormonal shifts, hydration, heat response, gut tolerance and recovery can all influence how training feels and how well the body adapts.

The work of Dr Stacy Sims and other researchers has helped shift the conversation around female physiology in endurance sport. It has made clearer what many women have felt in their own bodies for years: energy, temperature regulation, perceived effort, recovery and carbohydrate needs are not static.

This does not mean every session needs to become complicated. It means you need to pay attention. Your fuelling needs may shift depending on where you are in your cycle, how well you slept, how much stress you are carrying, whether you are in perimenopause, how hot the day is, how technical the terrain is and how depleted you were before you even started.

Start before the session starts

A strong fuelling strategy begins before you run.

Many female athletes under-fuel morning sessions because they are rushing, not hungry, trying to train the gut, or have absorbed the idea that fasted training is somehow more disciplined.

Before an easy morning run, this might be simple. A banana. Toast with honey. A few dates. A small bowl of oats. A sports drink. Something small and familiar. Before longer runs, hill sessions, strength work or back-to-back training, you need more deliberate preparation.

Practise eating while you move

Your gut is trainable.

Just as your legs adapt to hills and your lungs adapt to effort, your digestive system can adapt to taking in fuel while you move. But it needs repetition.

For most long trail runs, start with a simple rhythm: fuel every 30 minutes. That might be a gel, chews, a banana, sports drink, dates, rice cakes, boiled potatoes, a small wrap or another food you tolerate well.

Carbohydrate is not the enemy

Long-distance running uses a mix of fuel sources, including fat and carbohydrate. The longer you are out there, the more important it becomes to keep carbohydrate available so your body can continue to move well.

For many ultra runners, a useful starting point is to work toward 30 to 60 grams of carbohydrate per hour during longer sessions, then adjust based on duration, intensity, conditions, gut tolerance and individual needs.

This does not need to happen all at once. If you currently struggle to eat while running, begin with what you can tolerate, then gradually build the amount and consistency over time.

Match your fuelling to the terrain

Trail running changes the way fuelling feels.

On the road, effort can be steady. On the trail, your intensity rises and falls constantly. A climb may push your heart rate up. A descent may load your quads. Sand, mud, stairs, rocks and heat all increase the cost of movement.

This matters because you may be burning through energy faster than your pace suggests. A slow kilometre is not always an easy kilometre.

Consider your cycle, without becoming rigid

Menstrual cycle awareness can be useful, but it should not become another rulebook to judge yourself against.

In the luteal phase, which occurs after ovulation and before your period, some women notice changes in body temperature, appetite, fluid balance, perceived effort and carbohydrate needs. For others, the changes are subtle.

The point is not to assume every woman responds the same way. The point is to track what happens for you, then adjust with respect for your body.

Hydration is part of fuelling

Hydration is not just about water.

During long runs, especially in warm, exposed or humid conditions, you lose fluid and sodium through sweat. If you replace water without considering electrolytes, you may still feel flat, nauseous, headachy or depleted.

For ultra runners, hydration should be practised alongside carbohydrate intake. This might include electrolyte tablets, sports drink, sodium capsules, salty foods or a mix of these depending on your sweat rate, conditions and gut tolerance.

Race-day fuelling is built in training

Race day is not the time to try something new.

Your long runs are where you test the practical details. Can you open the packet while moving? Can you eat while hiking uphill? Can you tolerate gels in the heat? Do you need salty food after three hours? Does caffeine help or unsettle your gut?

Many ultra runners do not come undone because they lack mental strength. They come undone because they fall behind on energy, hydration and sodium, then ask their mind to solve a physiological problem.

What to practise on your next long run

Before you run, eat something. Even if it is small.

During the run, fuel every 30 minutes. Set a watch alert if you need to. For runs over 90 minutes, practise carbohydrate intake consistently, not just when you feel tired.

Carry more than you think you need. Separate your fuel plan from your hydration plan so you know how much carbohydrate you are taking in, rather than guessing. Afterwards, make a note of what worked, what felt easy, what sat badly and what you would change next time.

The deeper rhythm

At Her Trails, we do not see fuelling as a performance hack. We see it as a relationship with your body.

It is a way of listening earlier. It is a way of respecting the work you are asking your body to do. It is a way of building trust before the trail tests you.

You do not need to get it perfect. You need to get curious, practise consistently and stop treating food as something separate from your training.

The invitation

On your next long run, let fuelling become part of the session, not something you remember once the energy has already dropped.

Fuel before you are depleted. Fuel before your mood drops. Fuel before your legs feel empty. Fuel before the climb asks more of you.

Because in ultra running, fuelling is not just about getting to the finish line. It is about staying connected to yourself all the way there.