Eating around a long run

Unless your run lasts well over 90 minutes, the night before calls for an ordinary dinner with some carbs in it.¹ A giant bowl of pasta isn't required.

A 1997 review looked at carb loading, the practice of eating extra carbs in the days before an event to fill the muscles' fuel stores.¹ Extra stores made no difference to moderate running or cycling lasting 60 to 90 minutes. In those sessions, the muscles still had plenty of fuel left at the end.

For efforts longer than 90 minutes, the picture changed. Full stores delayed fatigue by about 20 percent.¹ In races over a set distance, high-carb diets improved times by 2 to 3 percent.

Real loading takes a lot of food. The International Society of Sports Nutrition is a professional society for the field.² It puts the amount that fills fuel stores at 8 to 12 grams of carbs per kilogram of body weight a day. For a 70 kg (154 lb) runner, that's 560 to 840 grams, far more than one big dinner holds.

Bottom line

Save carb loading for races longer than about 90 minutes. Before a training run, eat a normal dinner.

If your run will last longer than an hour, eat some carbs beforehand. For shorter runs, eating first matters much less.

A 2018 review of 46 studies found that eating before exercise improved performance in longer aerobic sessions, but not in shorter ones.³ A 2020 review set the dividing line at about 60 minutes.⁴ It also found that the amount eaten, anywhere from 25 to 312 grams, made little difference to time trial results.

The form doesn't matter much either. Solid food, gels and drinks worked about equally well in the studies that compared them.⁴ A medium banana has about 27 grams of carbs,⁵ and a medium plain bagel has about 55.⁶

Your stomach is the main limit. Between 30 and 50 percent of athletes report stomach or gut problems during exercise, and endurance athletes have them most often.⁷ Practicing your fueling in training is one way to reduce them.

Bottom line

Before a run longer than an hour, eat a breakfast with carbs that your stomach already knows.

On runs longer than about an hour, carbs taken during the run help you keep going. The usual target is 30 to 60 grams an hour.⁸

A 2011 review set 30 to 60 grams an hour as the target for longer sessions.⁸ For efforts over 2 and a half hours, it allowed up to 90 grams. A 2014 review scaled the advice to duration.⁹ It suggested small amounts for about an hour, and up to about 60 grams an hour for 2 to 3 hours.

Two medium bananas, at about 27 grams each, come to roughly 54 grams.⁵ That covers an hour of a long run at the upper end of the usual range.

Taking carbs during the run also makes breakfast less critical. The 2020 review found that eating during exercise shrank the gap between people who ate beforehand and people who didn't.⁴

Bottom line

For runs over an hour, carry something you can eat and practice taking it on the go.

Eating carbs and protein soon after a long run refills your muscles faster. That matters most when your next hard session is less than a day away.

In a 1988 study, 12 cyclists had a carb drink either right after a long ride or 2 hours later.¹⁰ Muscle fuel came back about three times as fast in the first 2 hours when they drank right away. Even after the delayed group finally had its drink, it refilled 45 percent more slowly than the early group had.

The sports nutrition society suggests 1.2 grams of carbs per kilogram per hour when you need to recover within 4 hours.² A little less carbohydrate with some protein added works too. For a 70 kg runner, 1.2 g/kg is about 84 grams, roughly a bagel and a banana.⁶⁵

Protein helps repair the legs. The same society suggests 20 to 40 grams of protein per serving.¹¹ If you won't run hard again until the day after tomorrow, the timing matters much less.² What counts then is that your meals that day cover your needs.

Bottom line

Eat carbs and 20 to 40 grams of protein within the hour if tomorrow is another training day.

1. 01

   Before a training run, a normal dinner with some carbs is enough.

2. 02

   Loading only helped in efforts longer than about 90 minutes.

3. 03

   Before runs over an hour, eat some carbs your stomach is used to.

4. 04

   During runs over an hour, aim for 30 to 60 grams of carbs an hour.

5. 05

   In the hour after, eat carbs and 20 to 40 grams of protein, especially if you train again soon.