Question 1

How much carbohydrate should a runner eat per day?

Accepted Answer

Carbohydrate intake should vary with training load — 3–5 g/kg/day on easy days, 6–10 g/kg/day during moderate-to-high volume training, and 8–12 g/kg/day during heavy training or the 36–48 hours before a marathon. This is carbohydrate periodization — fuel for the work required — and replaces the older idea of a single daily macro ratio.

Question 2

What is the maximum carbohydrate intake during a marathon?

Accepted Answer

Research from Jeukendrup, King, Podlogar and Viribay has validated in-race carbohydrate intakes of 90–120 g/hr in gut-trained runners, using glucose:fructose blends in 1:0.8 to 2:1 ratios. This is far above the old 60 g/hr textbook ceiling. Gut training — 4–8 weeks of progressive practice — is the prerequisite for tolerating these intakes without GI distress.

Question 3

What is RED-S and why should I care?

Accepted Answer

Relative Energy Deficiency in Sport (RED-S) is a syndrome of low energy availability — eating too little for your training load — that affects bones, hormones, immunity, metabolism, and performance in both male and female runners. Target energy availability is ≥45 kcal/kg fat-free mass per day. RED-S is the highest-stakes concept in runner nutrition; persistent low energy availability drives stress fractures, missed periods, and training plateaus.

Question 4

Are BCAAs worth taking as a runner?

Accepted Answer

No. BCAAs (branched-chain amino acids) are redundant when your total daily protein intake is adequate (1.6–2.0 g/kg/day for runners). Every high-quality protein source already contains BCAAs, and separate supplementation provides no meaningful benefit over dietary protein. Save your money for evidence-backed supplements like caffeine, creatine, collagen + vitamin C and iron (after testing).

Question 5

How much sodium should I take during a marathon?

Accepted Answer

Sodium needs during a marathon vary hugely — 300 mg/hr to 1,500 mg/hr depending on individual sweat sodium concentration and conditions. A sweat test (weigh-in protocol + optional patch-based sodium testing) gives you a personalized number. General guidance: 300–800 mg sodium per hour in temperate conditions, with a pre-race 500 mg bolus if you are a known salty sweater.

RUN
NUTRITION.

Quick tools

What runners use

Fuel by distance

Deep dives

Energy availability — the master variable every runner must understand

Fuel for the work required — carbohydrate periodization for runners

From 60 to 120 grams per hour — the in-race carbohydrate ceiling has moved

Pre-race fueling and carb loading — 1-day, 3-day, 6-day protocols

Hydration and electrolytes — individualized, not prescriptive

Race nutrition by distance — 5K, 10K, half, marathon, ultra

Supplements that actually work — the AIS ABCD framework for runners

Gut training — how to tolerate 90 g/hr without the pukies

Plant-based running — DIAAS protein, B12, algae EPA/DHA

Female runner nutrition — cycle phases, iron vigilance, and the honest science

Masters runners (40+) — 0.4 g/kg protein per meal, creatine, pre-sleep casein

The 4 Rs of recovery — Refuel, Rehydrate, Repair, Rest

Tendons and stress fractures — the nutrition side of injury recovery

Kipchoge's diet is boring — and that's the point

RUNNUTRITION.