How many carbs do endurance athletes actually need?
Carbs have become one of the most misunderstood topics in endurance sports.
Some athletes fear them, otthers think more is always better.
Most simply guess.
The truth?
Carbohydrates are one of the most important tools you have for performance, recovery, and long-term progress.
As both an endurance athlete and coach, one of the biggest lessons I’ve learned is this:
most endurance athletes don’t underperform because they train too little, they underperform because they underfuel.
Carbohydrates are your body’s preferred fuel source for:
higher intensity training
threshold work
VO₂max sessions
long races
repeated training days
Your body stores carbs as glycogen in:
muscles
liver
But glycogen stores are limited. That means:
if you train hard without enough carbs, you’re more likely to experience:
poor session quality
slower recovery
poor sleep
higher injury risk
increased fatigue
reduced immune function
Different research bodies all emphasize that meeting carbohydrate needs is essential to replenish glycogen and support training adaptation.
Your carbohydrate intake needs depend on:
training volume
intensity
body weight
goals
recovery demands
A useful guideline for most athletes is:
Light training / recovery days: 3–5 g per kg bodyweight / day
Example (70 kg athlete):
210–350 g carbs
Good for:
rest days
easy short sessions
Moderate training (around 1 hour/day): 5–7 g/kg/day
70 kg athlete:
350–490 g
Good for:
steady training weeks
moderate load
High training load (1–3 hours/day): 6–10 g/kg/day
70 kg athlete:
420–700 g
Good for:
endurance blocks
doubles
quality sessions
Very high load / race camps / Ironman prep: 8–12 g/kg/day
70 kg athlete:
560–840 g
Good for:
long rides
race weekends
heavy volume blocks
These ranges are broadly supported in current sports nutrition reviews and athlete guidelines.
For sessions:
longer than 60–90 min
high intensity
race-specific
Aim for: 1–4 g/kg in the 1–4 hours before training
Example: 70 kg athlete:
70–280 g
The closer to the session:
lower fiber
easier to digest
Examples:
oats + banana
toast + jam
rice + eggs
bagel + honey
Pre-exercise carb intake in this range helps top up glycogen and improve performance.
My experience as a coach and athlete has tought me that thhis is where many athletes leave performance on the table.
Sessions <60 min
Usually: no carbs needed (unless fasted / depleted)
60–150 min: 30–60 g/hour
Good for:
tempo sessions
long runs
hard rides
2.5–3+ hours: 60–90 g/hour (even 100+ g/hour if trained)
Especially for:
long rides
marathons
triathlon
race simulations
Longer events can benefit from higher carb intake, especially when using mixed carb sources (e.g., glucose + fructose) to improve absorption.
Practical examples:
sports drink
gels
bananas
bars
chews
Important: train your gut and don't wait until race day!
After hard or long sessions, recovery matters.
Aim for: ~1.0–1.2 g/kg in the first few hours
This helps:
restore glycogen
improve recovery
support next-day quality
Example: 70 kg athlete:
70–85 g carbs soon after training
Add:
20–40 g protein
This combination supports glycogen replenishment and muscle repair.
1. Eating too little because they want to stay lean
Low energy availability often:
kills recovery,
hurts hormones,
reduces adaptation.
2. Underfueling easy volume
Easy training still uses glycogen.
3. Not fueling during long sessions
This:
lowers quality,
increases stress,
slows recovery.
4. Only eating carbs around races
You need to support training first before you can fuel races.
As an endurance athlete, one of the biggest changes in my own performance came when I stopped treating carbs like something I had to “earn.”
What made the difference was:
eating enough around hard sessions,
fueling long rides properly,
recovering faster between blocks.
That led to:
better quality,
more consistency,
and better race performance.
Because good fueling lets your training actually work.
If you want to perform well as an endurance athlete, carbs are not optional.
They are:
fuel,
recovery support,
adaptation support.
The goal is: fuel enough for the work you’re asking your body to do and support performance as optimal as possible.
If you want help dialing in your training, recovery, and fueling based on your own goals and schedule, explore the coaching, courses, and resources on this site.
Because eating smarter is part of better performance.
