Daily Nutrition for Runners

Eat enough for the running you do

The first job of everyday eating is enough energy. Eating too little for what your running uses is called low energy availability, and the syndrome it causes is Relative Energy Deficiency in Sport (REDs), described in a 2023 International Olympic Committee consensus statement as poorer health and performance in women and men¹. It is common and it costs running. In a 2025 review, 44.7% of 6,118 athletes in 46 studies had low energy availability, and across the 59 studies in the review, those athletes ran worse, adapted less to training and missed more training with illness than athletes who ate enough².

Under-fueling shows up as feeling flat, always tired, and small aches that keep getting worse. Raise your food as your training rises, because hard weeks need more food, not the same food. If you are losing weight without meaning to, have lost or missed periods, keep getting injured, or find yourself restricting food or preoccupied with it, see a doctor or a sports dietitian before changing your training or your eating.

Do not cut calories and train hard at the same time. Choose one. Weight-loss work fits an easier training period, such as winter, better than the build to a big race, because strength and hard sessions need carbohydrate to be good quality. If you want to change your weight, cut discretionary calories, lift, ease your endurance volume, and work with a dietitian. Questions about body weight belong with a doctor or a dietitian, and the 2016 joint sports-medicine position statement says athletes should be referred to a registered dietitian for a personalized plan³. For women, see the guide on training considerations for women runners.

Carbohydrate rises with your training

Carbohydrate is the fuel you burn on the run and the thing your muscles restock afterward, so scale it to the day's training, in grams per kilogram of body mass. The standard bands from the 2016 joint position statement of the Academy of Nutrition and Dietetics, Dietitians of Canada and the American College of Sports Medicine³:

• Light training: 3 to 5 g/kg a day.
• Moderate, about an hour a day: 5 to 7 g/kg.
• High, one to three hours a day: 6 to 10 g/kg.
• Very high, more than four to five hours a day: 8 to 12 g/kg.

Matching carbohydrate to the day

For a 60 kg (132 lb) runner training one to three hours a day, 6 to 10 g/kg is about 360 to 600 g of carbohydrate a day. Eat toward the top of your band on your longest and hardest days and the bottom on easy days. The bigger amounts for the last day or two before a long race and for fuel during a run have their own guides on carb loading and carbohydrate during exercise.

Your muscle stores follow what you eat. A 2026 review of 63 trials pooled 18 of them. In the studies where the same people ate both ways, muscle glycogen was higher on more than about 6.5 g/kg a day than on less, and studies that compared different groups of people showed no clear difference. Glycogen is not running performance, but it is why a runner who trains most days should not live on a light-training diet⁴.

Keep carbohydrate up

Do not make low carbohydrate your everyday diet, whether to lose weight or to be healthy. In a 2026 review of 33 studies of trained athletes on low-carbohydrate or ketogenic diets, maximal aerobic capacity was preserved in half the studies, running economy at submaximal speeds was impaired in half, and studies that measured within a week found worse performance. The authors concluded that the evidence supports periodized carbohydrate strategies⁵, which means eating more carbohydrate on heavier training days, as the bands above do. Top coaches have also dropped fasted and low-carbohydrate training sessions: the adaptations they were meant to bring look more like stress than gains, and big energy gaps within a day hurt health and performance, more so in women. Low carbohydrate makes enough energy for the training harder to reach, and low energy availability is the problem described at the top of this guide. Keep carbohydrate up even when you are working on body weight with a doctor.

Protein

Aim for about 1.8 g of protein per kilogram of body mass a day, which is 108 g for a 60 kg runner. That is the amount a 2025 review advocates for endurance athletes. The same review found that endurance athletes habitually eat about 1.5 g/kg, that needs may exceed 2.0 g/kg on rest days and on days of carbohydrate-restricted training, and that there is no compelling evidence of a performance benefit from adding protein to carbohydrate before or during a run when carbohydrate recommendations are met⁶.

Spread it across the day, a serving at each meal, and add some to the meal after a long or hard run. Muscle gets harder to keep and build with age, especially for women in their 40s and older, so lift heavy and eat enough protein. See the guide on strength training for runners.

Before and after a run

Before a longer or harder run, a light carbohydrate snack one to two hours before is a common recommendation. Try it in training before you rely on it.

After a long or hard run, eat a meal with carbohydrate and protein soon after. What to take during a run, under 90 minutes and beyond, is in the guide on carbohydrate during exercise, and the overview is in fueling and hydration.