00WHAT THE SPORTS SCIENCE SAYS

Sweets for the
long miles.

A runner seen from behind on a quiet country lane at early morning, with a small zipped waist pouch at the back of their belt — AI-generated image, not a photograph of a real person or place.

A pocket of sweets is real race fuel.

On a long run your muscles burn through their stored carbohydrate. Sports nutrition research shows when topping it up helps, roughly how much per hour, and why practising it matters as much as the amount.

LITTLE AND OFTENonce the run goes longUpdated 16 October 2026

Check your run

01Principles

Short runs need little
Long runs need a plan
Practise it in training
Fuel matched to the distance

02THE SHORT ANSWER

How long you run
decides the fuel.

Research ties carbohydrate advice to time on your feet.
The longer the run, the more it matters.

UNDER AN HOUR

Little or nothing

A 2014 review found it is not necessary to take in large amounts of carbohydrate for exercise of about 30 minutes to an hour. A small amount, or even a mouth rinse, may be enough.

Check your run

TWO TO THREE HOURS

Little and often

For runs of 2 to 3 hours the same review suggests up to about 60 g an hour. Sweets, gels, drinks and low-fibre snacks all count; choose what sits well.

See the numbers

RACE DAY

Nothing new on the day

Reviews of runners' stomach problems advise practising your fuelling in training and avoiding fibre, fat and very concentrated drinks during the race.

How to practise

03A QUICK RUN CHECK

How long
are you out?

Pick the kind of run to see what sports nutrition research suggests about carbohydrate on the move. The bar shows how much fuelling matters for that run.

Figures are from reviews and position stands, mostly based on trained athletes. This is general information, not personal nutrition or medical advice.

Run check

Choose a runA 30 to 60 minute runOver an hour, running hardA 2 to 3 hour long runAn ultra or very long eventA slow 5-hour marathon

A 30 to 60 minute runLittle or none

Large amounts are not needed for exercise of about 30 minutes to an hour. Studies found a carbohydrate mouth rinse or a small amount could still help performance.

Over an hour, running hard30–60 g an hour

For hard efforts lasting more than 60 minutes, the ISSN suggests about 30 to 60 g of carbohydrate an hour, taken every 10 to 15 minutes, for example in a 6 to 8% sports drink.

A 2 to 3 hour long runUp to ~60 g an hour

A single type of sugar such as glucose can be used at up to about 60 g an hour, and that is the suggestion for exercise lasting 2 to 3 hours.

An ultra or very long eventUp to ~90 g an hour

For ultra-endurance events the suggestion rises to about 90 g an hour, but only as a mix of sugars, such as glucose with fructose, which the gut absorbs by different routes.

A slow 5-hour marathonAdjust downwards

The advice comes mostly from trained athletes. At lower running speeds less carbohydrate is burned, so the review says the amounts should be adjusted downwards.

Sources: Jeukendrup 2014, Sports Medicine 44(Suppl 1); International Society of Sports Nutrition position stand on nutrient timing, 2017.

04TWO NUMBERS WORTH KNOWING

The gut sets
the speed limit.

One figure on how fast sugar can be used,
one on how often stomachs object.

≈ 60g an hour

Glucose the body can use per hour

Glucose is absorbed by one transporter in the gut, which becomes saturated at around 60 g an hour. Adding fructose, which uses a different route, pushed use above that in lab studies.

ONE SUGAR · JEUKENDRUP 2014

30–50%

Athletes reporting gut complaints

Studies generally suggest 30 to 50% of athletes have gut complaints during exercise, and estimates for distance runners range from 30 to 90% depending on the study.

STOMACH TROUBLE · DE OLIVEIRA 2014

A large study of endurance events found carbohydrate intake varied widely between athletes, and was lowest in marathons and highest in cycling and triathlon (Jeukendrup 2014).

05FOUR HABITS TO PRACTISE

Train the plan,
then race it.

The research leans on one idea again and again: fuelling is a skill. Try these on long training runs, not for the first time on race day.

Start early, take it often
Little and often works better than one big hit. In one study cyclists did better taking the same dose every 30 minutes rather than every 60.
Pick what your stomach likes
Drinks, gels, sweets and low-fat, low-fibre bars all work. The review says the choice should be based on personal preference.
Drink with your fuel
Solid food and very concentrated sugar drinks can slow how fast fluid is absorbed, so plan water alongside your sweets.
Rehearse on long runs
Practising your race fuelling in training is advised to lower the chance of stomach trouble and may help the gut absorb more.

A road race drinks table seen from the side, with rows of paper cups of water and small bowls of sweets waiting for runners — AI-generated image, not a photograph of a real person or place.

06SUGAR OFF THE RUN

Race fuel is
not a daily habit.

A small handful of colourful jelly sweets and a soft-flask of water resting on a wooden bench beside a pair of running shoes — AI-generated image, not a photograph of a real person or place.

The NHS advises adults to have no more than 30 g of free sugars a day, and lists sweets among the foods to cut down on. An hour of race fuel can be twice that.

That is why sports advice ties sugar to the long session itself. Outside long or hard training, the everyday guidance on sweets, sugary drinks and teeth still applies.

07Questions

Questions people ask

Do I need sweets or gels for a 5K or 10K?

Usually not much. A 2014 review found large amounts of carbohydrate are not necessary for exercise of about 30 minutes to an hour, although a small amount or a mouth rinse may help.

How much carbohydrate should I take on a long run?

Reviews suggest up to about 60 g an hour for 2 to 3 hours of exercise, and about 90 g an hour for ultra-endurance events using a mix of sugars. Slower runners may need less.

Why do runners mix glucose and fructose?

Glucose is absorbed by a transporter that becomes saturated at around 60 g an hour. Fructose uses a different transporter, so a mix lets more carbohydrate be used per hour.

Why does my stomach play up on long runs?

Gut complaints are common in endurance sport. A review linked them with fibre, fat, protein and very concentrated sugar drinks taken during races, and with dehydration.

Can you train your gut?

Possibly. Animal studies show gut sugar transporters increase on a high-carbohydrate diet, evidence in people is limited, and practising race fuelling in training is still recommended.

08Sources

Sweets for the
long miles.