Carb Loading Calculator
From Bergstrom 1967 to Burke 2011: personalized carbohydrate targets and timing
Inputs
kg
Marathon (42.2K)
Modified Sherman (3 days, most common)
:00
Carb loading is useful for races longer than about 90 minutes (half marathon and above). For 5K/10K, eat normally.
Common Mistakes
- Too much fat: creamy or cheesy pasta sauce slows gastric emptying.
- Too much fiber: brown rice and whole grains can cause race-day bloating.
- Trying new foods: race week should be old-friend foods.
- Not enough fluid: each 1 g glycogen stores about 3 g water.
- Assuming more is better: above 10 g/kg gives little extra benefit (Burke 2011).
Personalized Carb Target
Daily carbohydrates
650 g
Rice equivalent
10.8 bowls
Pasta equivalent
867 g
Daily calories
4225 kcal
Pre-Race Timeline (Modified Sherman (3 days, most common))
D-7：Normal diet (5-6 g/kg/day)
Last long run one week out
D-6 to D-4：Taper training gradually + normal diet
Do not deliberately cut carbs
D-3：Raise carbs to 520g
Training down to 30 min easy pace
D-2：Carbs 650g (target dose)
20 min easy + 4×100 m strides
D-1：Carbs 650g (final day)
Rest or 0-15 min easy run; drink enough because glycogen stores water
Race breakfast T-3:00：163g carbs (easy to digest)
White toast + banana + honey / rice + chicken / oatmeal
Race T-0:30：30g carbs (gel / banana / sports drink)
Final pre-race top-up
Carbohydrate Reference Table (options to reach 650g)
| Food | Unit | Carbs (g) | Needed |
|---|---|---|---|
| White rice cooked | 1 bowl (200g) | 60 | 11 bowls |
| Pasta dry weight; about 220g cooked | 100g dry | 75 | 9 servings |
| White toast regular slice | 1 slice | 15 | 44 slices |
| Bagel plain | 1 bagel (~100g) | 50 | 13 bagels |
| Banana medium | 1 banana | 27 | 25 bananas |
| Sweet potato steamed / baked | 1 medium (130g) | 32 | 21 potatoes |
| Energy gel Maurten / GU | 1 packet | 25 | 26 packets |
| Sports drink 6% carbohydrate | 500 mL | 30 | 22 bottles |
You do not need one food only. Mixing options is easier and less monotonous.
Race-Day Breakfast (3-4 Hours Before Start)
Target: 1-4 g/kg carbohydrate (65 kg -> 65-260 g)
Example combinations:
- White toast 2-3 slices + 1 banana + honey (163g carbs)
- White rice 1 bowl + chicken breast + soy sauce (146g)
- Oatmeal + apple + maple syrup (154g)
At 30 minutes before start, add another 30g if needed (banana / gel / sports drink). Hawley & Burke 1997 supports small pre-race snacks for long events.
Research Basis
- Bergström et al. (1967, Acta Physiol Scand): foundational glycogen loading study; depletion plus loading can reach about 200% of resting glycogen.
- Sherman et al. (1981, Int J Sports Med): modified 6-day taper + high-carb approach without a painful depletion day.
- Bussau et al. (2002, Eur J Appl Physiol): Western Australia 1-day method: no depleting exercise needed — just rest plus 10 g/kg high-carb intake reaches supercompensation within 1 day.
- Burke et al. (2011, J Sports Sci consensus): for events at least 90 minutes, 10-12 g/kg/day for 36-48 hours is recommended; more adds little.
- Hawley et al. (1997, Sports Med): glycogen loading postpones fatigue by roughly 20% in events over 90 minutes and improves distance-based performance by 2-3%.