Nutrition for runners.
What you eat determines how you run — not just on race day, but across every training block. This guide covers the complete fueling picture: pre-run timing, mid-run calories, post-run recovery nutrition, hydration science, and the daily macro framework that supports consistent high-quality training over months and years.
Pre-run fueling: timing and composition
Eat 2-3 hours before a key session: 1-2g of carbohydrate per kilogram of body weight, low in fibre and fat to minimise GI distress. A 70kg runner needs 70-140g of carbs — roughly a bowl of oatmeal with banana and honey. For early-morning runs where a full meal is impractical, 30-50g of fast-digesting carbs (white toast, sports drink, or a gel) 30-45 minutes before starting provides sufficient top-up without stomach issues. Carb-loading for races means 8-10g/kg/day for 48-72 hours pre-race, not a single pasta dinner.
During-run nutrition: gels, real food, and timing
For efforts exceeding 75 minutes, begin fueling at 35-40 minutes with 30-60g of carbohydrate per hour. Glucose-only products (most gels) max out intestinal absorption at 60g/hour; dual-source glucose-fructose products push absorption to 90g/hour through parallel transport mechanisms. Aim for 200-300 calories per hour during marathon-effort runs. Real food options — dates, rice cakes, boiled potatoes — work well for ultra distances where gel fatigue sets in after hour four. Start early, dose consistently, and never wait until you feel depleted.
Post-run recovery nutrition: the 30-minute window
Consume 20-40g of protein plus 1-1.2g/kg of carbohydrate within 30-60 minutes post-run to maximise glycogen replenishment and muscle protein synthesis. The glycogen synthase enzyme is most active immediately after exercise, making this window physiologically real — not marketing. A recovery shake with whey protein and fruit, or a meal of chicken and rice, covers both needs. For double-session days, aggressive recovery nutrition between sessions is the difference between quality work and junk miles.
Race-day nutrition strategy
Race-day nutrition is not improvised — it is rehearsed. Practice your exact race fueling protocol on at least 6 long runs before the event: same products, same timing, same quantities. For a marathon, plan gel or fuel intake at kilometres 7, 14, 21, 28, and 35. Walk through aid stations to drink properly — the 8 seconds lost is recovered many times over by better absorption. Never try a new product, brand, or flavour on race day. Your gut has trained for a specific protocol; respect it.
Hydration: sweat rate, sodium, and overhydration risks
Measure your sweat rate: weigh yourself before and after a 60-minute run without drinking. Each kilogram lost equals roughly one litre of sweat. Most runners lose 0.5-1.5L per hour depending on conditions. Replace 60-80% of losses during running — full replacement is neither necessary nor practical. Sodium losses average 400-1200mg per litre of sweat; use electrolyte products for efforts over 90 minutes. Hyponatremia — dangerously low blood sodium from overdrinking plain water — hospitalises hundreds of marathon runners annually. Drink to thirst, not to a fixed schedule.
Daily nutrition for training: macros, iron, and vitamin D
A runner training 50-80km per week needs 5-7g/kg/day of carbohydrate, 1.4-1.7g/kg/day of protein, and 1.0-1.5g/kg/day of fat. Iron deficiency is the most common nutritional limiter in distance runners, particularly in menstruating athletes — ferritin below 30ng/mL impairs oxygen transport even without clinical anaemia. Get levels checked annually. Vitamin D supports bone remodelling and immune function; runners in northern latitudes or who train indoors should supplement 1000-2000 IU daily. Periodise nutrition with training: eat more carbs on hard days, moderate on easy days.
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