From the Coach guide
When to eat during a run, how much, and why you drink to thirst.
Under 60 min, you need only water, and only on a warm day. From 60 to 90 min, fuel is optional. From 90 min, eat or drink carbohydrate during the run.
About 25 g of carbohydrate each hour. On runs of 2 h 30 min or more, or long runs with race-pace parts, about 50 g. 25 g is about 1 gel, 3 chews, 16 oz of sports drink or a banana. Brands are different, so check the label. Choose the fuel you like in Settings, then Your Runs.
Start about 45 min into the run, before you feel flat. Carbohydrate takes time to reach your muscles. If you wait until you feel tired, it is too late.
Drink when you are thirsty. Do not drink on a schedule. Too much water can lower the sodium in your blood, and that is dangerous. If you feel sloshy, drink less. On a warm day, carry more water.
Before a run of 90 min or more, eat something light 30–60 min before, or a normal meal 2–3 h before. After, eat a normal meal with carbohydrate and protein.
Some runners race on more than 60 g of carbohydrate an hour. That needs a mix of sugars and practice over several weeks. Coach does not plan it.
If you have diabetes or another medical condition, ask your doctor before you change what you eat or drink on runs.
Drink to thirst: an international consensus on exercise-associated hyponatremia (2015). 30–60 g an hour: the 2016 sports nutrition position stand, and Mayo Clinic's guidance for runners. The time limits and serving sizes are app choices.
International consensus statement, 17 experts
Drinking when thirsty prevents both too little fluid and too much. Drinking beyond thirst is the main cause of low blood sodium during exercise.
A consensus of experts, not a trial. People with medical conditions may need other advice.
Joint position stand of 3 professional bodies; health-system guidance for runners
About 30–60 g of carbohydrate an hour for exercise of about an hour or longer. Mayo Clinic Health System gives the same range for runs over 90 minutes. More, up to 90 g an hour, applies to events of 2.5 hours or more and needs a mix of sugars.
Written for athletes in general, not only casual runners. The minute limits and serving sizes in Coach are app choices.
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