Carbohydrate loading — deliberately increasing muscle glycogen stores above normal levels in the days before an endurance event — is one of the most evidence-based performance nutrition strategies available for endurance athletes. It has real benefits for the right events, is frequently misapplied to the wrong situations, and requires execution of a specific protocol to work as intended.
When Carbohydrate Loading Works
Carbohydrate loading produces meaningful performance benefits only in endurance events lasting 90 minutes or longer at sustained moderate-to-high intensity. For shorter events or lower-intensity activities, glycogen stores are not limiting — loading them higher than normal provides no additional benefit and simply adds unnecessary weight (glycogen is stored with three times its weight in water).
The events where loading has consistent evidence: marathons and half marathons (borderline for halves, depending on target time); long-distance cycling events; triathlons of Olympic distance or longer; team sports with sustained high-intensity demands over 90 minutes; and open water swimming events of significant duration.
The Classic Protocol
The original carbohydrate loading protocol (the Scandinavian model) involved a depletion phase followed by a loading phase — a week-long process that is physiologically stressful and has been largely superseded. Modern protocols are simpler and produce similar glycogen elevations without the depletion phase.
The current evidence-based protocol: reduce training volume significantly in the three days before competition; increase carbohydrate intake to 10–12g per kg of body weight daily for the last one to two days before the event; maintain normal protein and fat intake (carbohydrates replace, not add to, total calories); ensure adequate hydration as glycogen storage requires water. For a 70kg athlete, this means 700–840g of carbohydrate daily — a substantial increase from typical intakes that requires planning across all meals.
What to Eat for Loading
During loading, carbohydrate quantity matters more than quality — the goal is maximum glycogen storage, not optimal nutrition. White rice, pasta, bread, potatoes, and sports foods are all appropriate. High-fibre carbohydrates should be moderated during loading because increased fibre intake can cause gastrointestinal discomfort at exactly the wrong time. The day before a race is not the time to experiment with high-fibre wholegrains.
Common Mistakes
The most common carbohydrate loading mistakes: starting too late (the final meal before a race cannot load glycogen — the process requires 24–48 hours); not reducing training volume alongside increasing carbohydrate intake; adding fat alongside carbohydrates (adding butter and cream to pasta increases calories without increasing glycogen); and loading for events that are too short to benefit. Read our pre-workout nutrition guide for the event-day nutrition that follows loading.
Fuel Your Training With Vanda's Kitchen
Quality daily nutrition is the foundation of consistent athletic performance. Vanda's Kitchen's fresh Filipino-inspired lunches — certified halal, 100% nut-free, built around lean proteins, complex carbohydrates, and fresh vegetables — provide the nutritional base for active London professionals balancing demanding careers with regular training. Sport England and the British Heart Foundation both emphasise that regular physical activity combined with a balanced diet is the most effective health investment available. View our team lunch options or WhatsApp us for City of London office delivery.
Quality daily nutrition is the foundation of consistent athletic performance. Vanda's Kitchen's fresh Filipino-inspired lunches — certified halal, 100% nut-free — provide lean proteins, complex carbohydrates, and fresh vegetables for active London professionals. Sport England and the British Heart Foundation both emphasise regular activity combined with balanced diet as the most effective health investment. View our team lunch options or WhatsApp us.
Frequently asked questions
Does carbohydrate loading cause noticeable weight gain before a race?
Yes, temporarily. Glycogen is stored alongside roughly three times its weight in water, so a full loading protocol typically adds one to two kilograms of body weight. This is normal and expected, and the weight disappears within the first hour or two of racing as glycogen is used.
Can you carbohydrate load without eating pasta?
Pasta is popular but not required. White rice, bread, potatoes, and rice-based sports foods all achieve the same glycogen elevation. The goal is maximum carbohydrate quantity with low fibre, so any easily digestible starchy food works equally well.
Does carbohydrate loading help in a half marathon?
The benefit depends on your target finish time. Runners completing a half marathon in under 90 minutes are unlikely to benefit meaningfully, as glycogen stores are rarely the limiting factor at that duration. Runners aiming for 90 minutes or longer may see modest benefit, particularly if their training nutrition has not been consistent.
Should I change my loading strategy if I am doing a triathlon rather than a road race?
The core protocol is the same, but triathletes need to account for the multi-discipline structure. The swim consumes glycogen before the primary fuelling opportunity on the bike, so arriving at the start with fully loaded stores is arguably more important than for a road race where you can begin fuelling immediately.
Is there any risk to carbohydrate loading for recreational athletes?
For otherwise healthy athletes, the physiological risks are minimal. The main practical risks are gastrointestinal discomfort from too much fibre during the loading phase, and poor sleep from eating large quantities late in the evening. Both are easily managed by choosing low-fibre sources and timing the bulk of intake earlier in the day.