Fuelling for Female Ultra Runners
Trail Notes | Training Nutrition
a practical reference for women
Fuelling for Female
Ultra Runners.
This is a practical reference for female ultra runners. It covers daily intake, long-run fuelling, race nutrition, common mistakes and the female-specific factors that change how we should think about training nutrition. It is written to be used, not just read.
The numbers below are guidance ranges drawn from current sports nutrition consensus for endurance athletes. They are starting points, not prescriptions. Your individual needs depend on body size, training load, life stage, gut tolerance and history.
If you have a history of disordered eating, low energy availability, REDs, GI disease or any medical condition that influences nutrition, work with a sports dietitian. This article does not replace individualised care.
The short version
Eat enough across the day. Match carbohydrate to training load. Do not skip pre-run fuel. Practise race fuelling in training. Build toward about 60 grams of carbohydrate per hour for long efforts, starting at 40 to 50 grams if fuelling is new to you, and up to 90 grams only if your gut is trained for it. Recover within 30 to 60 minutes of finishing. Do not under-eat as a strategy.
Section 01
Daily fuelling: getting the base right
Many fuelling problems in female ultra runners do not start in a race. They start in everyday under-eating. Your daily intake is the foundation. If the base is low, no race-day strategy will fix it.
A workable starting framework for a training female ultra runner:
Daily intake guidance
Carbohydrate
5 to 8 g per kg bodyweight on training days. Up to 8 to 10 g per kg on high-volume or back-to-back long-run days.
Protein
1.6 to 2.2 g per kg bodyweight, spread across 4 to 5 meals or snacks of roughly 25 to 40 g.
Fat
Around 1 g per kg as a minimum. Important for hormones, satiety and absorption of fat-soluble vitamins.
Energy availability
Aim to keep energy availability above 45 kcal per kg fat-free mass per day. Below 30 is the threshold most strongly linked with REDs.
Iron and ferritin
Test annually at minimum. Many female endurance athletes run low. Treat under guidance of a doctor or sports dietitian.
Hydration baseline
30 to 40 ml per kg bodyweight daily, plus replacement for sweat losses in training.
Ranges adapted from current IOC and sports nutrition consensus guidance for endurance athletes. Adjust to individual context.
Section 02
Carbohydrate periodisation by session
Not every session needs the same fuelling. Match carbohydrate to the demand of the work.
Base Run, under 60 min
Eat normally before and after. Water during is usually enough.
Moderate run, 60 to 90 min
Pre-run snack with 30 to 60 g carbs 1 to 2 h before. Fuel runs over 60 minutes: start in the first 30 to 45 minutes.
Long run, 2 to 4 h
Pre-run meal with 1 to 3 g carb per kg, 2 to 3 h before. In-run: build toward about 60 g carbs per hour, starting at 40 to 50 g if fuelling is new to you, never below 40 g. Start in the first 30 to 45 minutes.
Long run, 4 h+
Treat as race rehearsal. Aim for about 60 g carbs per hour, up to 90 g only if your gut is trained for it. Practise mixed carbohydrate sources, sodium, real food and gels in combination.
Strength session
Eat carbs and protein before and within 60 min after. We do not prescribe fasted training: fuel your sessions.
Recovery day
Maintain protein and overall energy. Carbs can be slightly lower but should not drop dramatically.
Section 03
In-run fuelling targets
Carbohydrate intake during running is one of the most reliable performance levers. Many female ultra runners under-fuel during long efforts. Build this skill gradually. Do not jump to 90 g per hour without training the gut to handle it.
Carbs per hour during running
Under 60 min
0 to 30 g per hour, optional. Mouth rinse only is fine for shorter efforts.
60 to 120 min
Start in the first 30 to 45 minutes and build towards 60 g per hour from a single carbohydrate source such as glucose or maltodextrin.
2 to 3 h
60 g per hour as standard. Begin using mixed carbohydrate (glucose + fructose) to improve absorption.
3 h+
About 60 g per hour using a glucose-to-fructose ratio of about 2:1 or 1:0.8. Higher intakes, up to 90 g, require trained gut tolerance.
Ultra (50 km+)
About 60 g per hour with a 40 g floor, up to 90 g only if your gut is trained for it and you want to, with planned shifts to real food, savoury options, soup or broth as the race progresses.
Spread intake across the hour rather than taking a large amount at once. Many athletes tolerate small servings every 15 to 20 minutes better than one large hit per hour.
Section 04
Hydration and sodium
Hydration needs vary enormously. Do not copy what a male teammate is drinking. Test your sweat rate by weighing before and after a 1 hour run in similar conditions to your race.
Fluid during running
400 to 800 ml per hour as a typical range. Adjust up in heat. Do not drink to a fixed plan if you are not thirsty and not sweating.
Sodium during running
Drink to thirst and add sodium to taste or to your own sweat test; there is no safe fixed amount per hour.
Sweat rate test
Weight loss per hour (kg) x 1000 = ml of sweat lost per hour. Replace 50 to 80 percent during, the rest after.
Hyponatremia risk
Has been reported more often in women, especially in long ultras. Caused by drinking more fluid than you lose; sodium intake does not prevent it, so drink to thirst rather than to a schedule. Symptoms include nausea, headache, swelling, confusion. If symptoms are severe, stop and seek medical help.
If you are gaining weight during an ultra, you are drinking too much. Slow down fluids and increase sodium.
Section 05
Pre-run and pre-race fuelling
Pre-race intake matters more than most runners realise. Race-morning nerves often push women to eat less than they need. That is a common reason for an early bonk.
Race-morning timing
3 to 4 h before
Main meal: 1 to 3 g carb per kg. Familiar foods, low fibre, low fat, moderate protein. Examples: oats with banana and honey, white toast with jam, rice with eggs.
60 to 90 min before
Top-up snack: 30 to 60 g carbs. Banana, sports drink, small portion of toast or a sports bar.
15 to 30 min before
Final top-up: a gel or 200 to 300 ml of sports drink if it sits well in training.
Race start fluid
5 to 7 ml per kg, 2 to 4 hours before. Sip, do not gulp.
Caffeine
3 to 6 mg per kg, 30 to 60 min before, only if practised in training. Do not introduce caffeine on race day.
Avoid new foods, high-fat dishes, high-fibre meals or large portions you have not tested. The race-week kitchen is not the time for experiments.
Section 06
During the ultra: a usable race plan
Build a written hourly plan and rehearse it. Use a vest pocket card, a watch screen reminder, or a crew sheet. Do not rely on memory under fatigue.
Hourly race-day template (50 to 100 km)
Hour 1 to 2
60 g carbs. Mostly liquid or gel. Start in the first 30 to 45 minutes. Drink to thirst. Do not under-fuel because you feel fresh.
Hour 3 to 5
About 60 g carbs, more only if your gut is trained for it. Begin alternating sweet and savoury. Add solid food at aid stations: rice balls, sandwiches, salted potatoes.
Hour 5 to 8
About 60 g carbs, never below 40 g. Soup, broth and warm food often become more palatable. Watch sodium closely.
Hour 8+
Eat what you can keep down, staying as close to your 60 g target as your gut allows, and not below 40 g. Lower sweet, increase salt and simple savoury carbs.
If the gut shuts down, simplify. Walk for 5 to 10 minutes, sip flat cola or broth, return to small frequent sips. Do not stack fuel on top of a closed stomach.
Section 07
Recovery fuelling
Recovery starts the moment you stop running. Do not wait until you feel hungry to eat.
Within 30 to 60 min
1 to 1.2 g carb per kg plus 0.3 to 0.4 g protein per kg. Example: yoghurt and granola, recovery shake, sandwich with eggs.
Within 2 to 3 h
A balanced meal with carbs, protein, vegetables and some fat. Eat enough that you do not feel like grazing all evening.
Fluid replacement
125 to 150 percent of weight lost, spread over 4 to 6 hours. Include sodium and food, not water alone.
Bedtime
After very long sessions, a 20 to 40 g protein snack before sleep supports overnight muscle repair.
Day after
Keep eating well. One good meal does not finish recovery from a long ultra. Full glycogen restoration can take 24 to 48 hours.
Section 08
Female-specific considerations
Life stage can change nutrition demand. Pregnancy, postpartum and perimenopause can all shift the picture. Some women notice patterns across the month, and some do not. Track your own: we train the person, not the phase.
Heavy periods
Iron loss can be significant. Pair iron-rich foods with vitamin C. Test ferritin annually with your doctor.
Perimenopause
Protein needs may shift higher (2.0 to 2.2 g per kg). Carbohydrate timing around training can become more important for recovery.
REDs / low energy availability
Warning signs: missing periods, recurrent injury, poor sleep, low mood, persistent fatigue, frequent illness. Seek qualified support.
Fasted training
We do not prescribe fasted training. Fuel your sessions.
Be cautious with trends that advocate routine fasting, very low carbohydrate intake or aggressive restriction. The evidence base supporting these approaches in female endurance athletes is weak. The evidence supporting their harms is growing.
Section 09
Gut training
The gut is trainable. If you cannot tolerate about 60 g of carbohydrate per hour, that is a training problem, not a fixed limit. Build tolerance the same way you build mileage: progressively and consistently.
A simple progression
Weeks 1 to 2
30 g per hour on long runs. One carb source only. Note any GI symptoms.
Weeks 3 to 5
45 to 60 g per hour. Introduce mixed-carb products (glucose plus fructose).
Weeks 6 to 8
60 to 75 g per hour. Add real-food trial in last hour of long runs.
Weeks 9+
Hold about 60 g per hour, or build toward 75 to 90 g only if your gut is trained for it and you want to. Practise full race-day intake on back-to-back long days.
If GI distress is consistent, look at fibre intake in the 24 hours pre-run, fat content of pre-run meals, hydration concentration, and running pace at the time of fuelling. These four factors are common culprits in race-day gut problems.
Section 10
Common mistakes
What to watch for
Under-eating daily
Long-term restriction undermines adaptation, recovery, hormones and immunity.
Skipping breakfast pre-long
Sets the run up to fall apart in the second half.
Too much fibre on race week
Reduce intake from 2 days out. This is not the week for kale and lentils at every meal.
New products on race day
Aid stations and goodie bags are full of items you have never trained with. Carry your own.
Drinking only water
Hyponatremia in long ultras comes from drinking more than you lose, not from a lack of sodium. Drink to thirst and add sodium to taste.
Late-race deficit chasing
You cannot make up a 500-calorie hole at hour 6. Front-load fuelling.
Trusting wearables alone
Calorie estimates from watches are unreliable. Use them as rough trend data, not exact figures.
Section 11
Worked examples
To illustrate how the numbers play out, here are two example athletes. These are templates, not prescriptions. Adapt to your context.
Example 1 · 60 kg athlete, 50 km race
Daily training: 300 to 480 g carbs, 95 to 130 g protein, 60 to 80 g fat.
Pre-race breakfast (3 h out): 90 g carbs, e.g. oats with banana, honey and a coffee.
Pre-race top-up (45 min out): 30 g carbs, e.g. a gel and small sips of sports drink.
In-race fuelling: 60 to 75 g carbs per hour. Roughly 2 gels plus 500 ml of sports drink each hour, with savoury aid-station food from hour 3.
Sodium: to taste or to your own sweat test; there is no safe fixed amount per hour.
Example 2 · 65 kg athlete, 100 km race
Daily training (peak weeks): 450 to 600 g carbs, 110 to 140 g protein, 70 to 90 g fat.
Pre-race breakfast (3 to 4 h out): 100 to 130 g carbs, e.g. rice with eggs and toast with jam.
In-race fuelling: Target about 60 g carbs per hour, going up toward 75 to 90 g only if the gut is trained for it, then stay as close to that as appetite and gut allow and never below 40 g.
Fluid: 500 to 700 ml per hour, adjusted to temperature and sweat rate.
Sodium: to taste or to your own sweat test; there is no safe fixed amount per hour.
Section 12
When to get help
There are situations where self-managed fuelling is not appropriate. Work with a sports dietitian or qualified clinician if any of the following apply.
You have missed 3 or more consecutive periods.
You have a history of disordered eating, restriction or compulsive exercise.
You are experiencing recurrent stress fractures or chronic injuries.
You feel persistently fatigued, low or unable to recover from sessions.
You are pregnant, postpartum or breastfeeding.
You have a diagnosed GI condition or food allergies.
You are entering perimenopause and noticing significant shifts in recovery or sleep.
Asking for support is not a weakness. It is good practice. The athletes who fuel best across the long term often have a qualified person checking their work.
Section 13
Final checklist
Daily intake hits carbohydrate, protein and fat ranges for your bodyweight.
You eat before long runs and recover within 60 minutes after.
Long-run fuelling matches race-day targets and gut tolerance is trained.
You have a written hourly race plan with carbs, sodium and fluid targets.
You know your sweat rate and have tested your sodium needs.
Iron and ferritin have been checked in the last 12 months.
You are not using fasting, restriction or low-carb approaches without qualified support.
A note on personal plans
If you want a plan built for you
The numbers in this guide are starting ranges. They are not a replacement for an individualised plan. If you want fuelling that is tailored to your physiology, your training load, your race demands and your gut, we recommend working with an accredited sports dietitian.
Her Trails recommends Tamara Madden of Madden Nutrition. Tamara works with female endurance athletes, understands the demands of trail and ultra racing, and builds practical, evidence-based plans that adapt to where you are in life and training.
Recommended Sports Dietitian
Tamara Madden
Madden Nutrition · Personalised fuelling for female endurance athletes
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