Carbohydrate Loading
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Carbohydrate loading maximizes muscle glycogen before long endurance events by eating high-carb (10–12 g/kg/day) for a day or two while tapering training.
Detail
Carbohydrate (glycogen) loading temporarily supersaturates muscle glycogen above normal to delay fatigue in prolonged endurance events — it benefits continuous efforts longer than about 90 minutes (marathons, long-distance triathlons, century rides), not short events.
The modern protocol is simpler than the classic 1960s depletion-then-load regimen: in the 1–3 days before the event, while tapering training (see Progressing Cardio Training), eat a high carbohydrate intake of about 10–12 g/kg of body weight per day (some protocols use ~8–12 g/kg). One- to two-day loads achieve near-maximal stores without the discomfort and risk of the old week-long depletion phase. Choose mostly easily digested, lower-fiber carbohydrate sources to limit GI bulk.
Expect water-weight gain: because each gram of glycogen stores ~3 g of water (see Glycogen — Stored Carbohydrate Fuel), successful loading adds a couple of pounds of glycogen-bound water — normal and not fat. On event day, continue with a familiar pre-event carbohydrate meal and in-race fueling (see Endurance Fueling). Loading is unnecessary — and just adds weight — for short or moderate sessions; reserve it for genuinely long efforts.
Key facts
- Benefits continuous endurance events >~90 min; useless for short events.
- Modern protocol: ~10–12 g/kg/day carbohydrate for 1–3 days while tapering.
- One- to two-day loads suffice; no week-long depletion needed.
- Expect ~2 lb water-weight gain (3 g water per g glycogen) — not fat.
- Continue pre-event meal and in-race fueling on the day.
Connections
- Glycogen — Stored Carbohydrate Fuel — the store being maximized; explains water gain.
- Endurance Fueling — event-day and in-race fueling.
- Carbohydrate Timing for Endurance — broader carbohydrate timing.
- Progressing Cardio Training — training reduction that accompanies loading.
Sources
See how this applies in practice, with honest limits on what the plan changes.
Educational content only — not medical advice. Always consult a qualified professional for individualized guidance, especially around injury, pregnancy, or medical conditions.