Training Nutrition for High-Mileage Runners (50-90 mpw)

Most runners don't bonk on race day because of a bad gel. They bonk because they've been three hundred calories short for weeks. This is about the baseline — what you eat on a random Tuesday in a marathon build at 65 mpw.

Daily calorie reality

A 70 kg runner doing 70 mpw at 8:00/mile burns roughly 560 kcal/day from running alone. Resting metabolic rate for that runner is around 1,650 kcal/day. Daily activity adds another 500-700 kcal. So the baseline daily need is about 2,800-3,000 kcal, and rises with heat, hard workouts, and long runs.

Most runners chronically under-eat during hard training blocks. The combination of suppressed appetite from high volume, bad advice to "create a deficit" while training hard, and the cognitive difficulty of eating 3,000+ kcal of real food every day adds up. By week 10 of a build, a lot of runners are down 4-6 lb and wondering why workouts feel sluggish.

Macros for high-mileage

Carbohydrate: 5-9 g/kg/day

This is the most variable macro, and the one most runners get wrong. General guidance by volume:

Weekly miles	Carbs (g/kg/day)
30-40 mpw	4-6
40-60 mpw	5-7
60-80 mpw	6-8
80+ mpw	7-9

For a 70 kg runner at 70 mpw, that's 420-560 g of carbs per day. Hitting the upper end means eating oats for breakfast, rice or pasta at two meals, fruit as snacks, and a carb-forward dessert. It's more food than most people realise.

Protein: 1.4-1.7 g/kg/day

Endurance runners don't need as much protein as strength athletes, but higher than the general 0.8 g/kg RDA. 100-120 g per day for a 70 kg runner. Distribute across 4-5 feedings of 20-30 g each to maximise muscle protein synthesis. Post-long-run and post-workout meals should get the higher end.

Fat: the rest

Fat fills in remaining calories. Typically 0.8-1.2 g/kg/day. No specific targets beyond "enough." Include mono- and polyunsaturated sources (olive oil, avocado, nuts, fatty fish) for general health.

Daily pattern: easy-day vs workout-day

Protein and fat stay roughly constant. Carbs flex.

Easy day (recovery 4-8 miler)

• Breakfast: oatmeal + fruit + eggs. ~100 g carbs, 25 g protein.
• Lunch: chicken + rice + vegetables. ~80 g carbs, 35 g protein.
• Snack: apple + peanut butter. ~35 g carbs.
• Dinner: fish + sweet potato + vegetables. ~60 g carbs, 30 g protein.
• Evening: yogurt + honey. ~25 g carbs, 15 g protein.
• ~300 g carbs, 105 g protein, 80 g fat, ~2,500 kcal.

Workout day (track or tempo)

Add 100-150 g of carbs. Example: add a bagel before the workout, extra rice at dinner, and a sports drink during the workout.

Long-run day

Add 150-250 g of carbs. Breakfast is bigger (pancakes, or bagel + banana + oatmeal). In-run fueling adds 150-300 g depending on the run length. Post-long-run is a full meal with big carbs and protein inside 60-90 minutes.

Warning signs of under-fueling

Low energy availability (LEA) and its more serious form, RED-S (Relative Energy Deficiency in Sport), are common in endurance runners. Signs to watch:

• Workouts feel harder than the pace suggests — 7:00 pace that felt comfortable in January feels labored in March despite "more fitness"
• Persistent fatigue not explained by sleep or workload
• Frequent colds or injuries
• Missed periods in female runners, or a >25% drop in morning testosterone-related signals in male runners
• Unintended weight loss of more than ~2 lb during a training block
• Mood changes: irritability, depression, loss of interest in running itself
• Poor sleep despite physical fatigue
• Slow wound healing or bruising

If two or more of these are present for more than 2-3 weeks, add calories aggressively and consider working with a registered dietitian who specialises in endurance athletes. This isn't a "push through it" situation.

Iron and other common gaps

Iron / ferritin

High-mileage runners lose iron through foot-strike hemolysis and sweat. Female runners are especially vulnerable. Annual ferritin check is reasonable; supplement under physician supervision if ferritin drops below 30 ng/mL. Don't self-supplement megadoses — iron toxicity is real.

Vitamin D

Widespread deficiency in populations that train indoors or at high latitudes. Check annually. Supplement to maintain 30-50 ng/mL.

Calcium and bone

Especially relevant in ultra-runners with any LEA history. 1000 mg/day from food or supplements. Dairy, leafy greens, fortified plant milks.

Timing principles

Pre-workout (before quality sessions)

For morning workouts, 30-50 g carbs + 200 mL fluid 15-30 min before is enough. For afternoon workouts, a carb-forward lunch 3 hours prior plus a small snack 30 minutes before.

During long runs

Anything over 75 minutes benefits from in-run carbs. Anything over 2 hours needs them. Train your gut the way you'll race: gel cadence, drink-mix, the whole kit. The training run is the rehearsal.

Post-workout / post-long-run

Within 60-90 minutes: 1 g/kg carbs + 20-30 g protein. Doesn't need to be perfect. A bowl of cereal with protein powder on top is fine. A burrito is fine. Whatever you'll actually eat.

Do I need to track every meal?

Depends on the question you're trying to answer. If you're hitting paces, sleeping well, and your weight is stable — probably no. If you're struggling with fatigue, trying to change body composition, or troubleshooting under-fueling, a 2-3 week tracking window gives you data to act on. Most runners who try tracking find they were short on carbs by 500-800 kcal on hard days and had it right on easy days.

Method doesn't matter much. A paper journal, a notes app, or a calorie tracking app all work. What matters is being honest about what you ate, including the second dinner and the trail-mix snack. The point isn't precision; it's visibility.

Related

• Post-Run Recovery Nutrition — the 30-120 min window
• Carb Loading Explained — race-week protocol
• Marathon Nutrition Guide — race-day side
• Calorie Tracking Apps for Runners — tools