How to Fuel for a Half Marathon: Science-Backed Nutrition with Unived

Running a half marathon (21.1 km) pushes your body beyond stored energy reserves. Without a solid fueling plan, glycogen depletion, electrolyte imbalance, and hydration challenges can slow you down or even prevent you from finishing strong.

This guide explains how to fuel a half marathon step by step, using Unived Endurance Nutrition products - Gel 100, Gel 180, and Salt Caps - and the sports science behind the strategy.

Why Fueling Matters in a Half Marathon

A half marathon typically lasts between 90 minutes and 2.5 hours for most recreational runners. That’s long enough for three key challenges to emerge:

1. Limited Glycogen Stores
   The body stores about 400–500 g of glycogen, enough for ~90–120 minutes of running. Beyond that, energy levels dip unless you refuel mid-race.
   
   
2. Carbohydrate Oxidation Rates
   Research shows the body can absorb ~60 g/hour from glucose alone, but combining glucose + fructose (multiple transportable carbs) allows up to 90 g/hour. This spares glycogen and delays fatigue¹²⁶.
   
   
3. Electrolyte Loss Through Sweat
   Sodium losses can range from 300–1000 mg/hour. If not replaced, dehydration and cramps can occur³⁴.
   
   
4. Caffeine Support
   Moderate caffeine intake (3–6 mg/kg) can boost endurance, focus, and perceived effort⁵.
   

Unived Half Marathon Fueling Plan

Here’s a proven plan to cover carbs + electrolytes during your race, using Unived endurance products.

Pre-Race (30–45 Minutes Before Start)

• Unived Gel 100 – 25 g carbs, 100 kcal

• Drink 200–300 ml water

Why? This primes your glycogen stores and stabilizes blood sugar before the gun goes off.

During the Race

Aim for 50–60 g carbs/hour + sodium replacement.

• At 30-35 min:

  • Unived Gel 180 - 45 g carbs, sustained release
  • Provides multi-transportable carbs for efficient absorption and long-lasting energy.
    
    

• At 60–70 min:

  • Unived Salt Cap + ~200 ml water

  • Replaces sodium to support hydration and prevent cramps.
    
    

• At 80-85 min:

  • Unived Gel 100

  • Quick glucose boost to hold pace in the second half.
    
    

• At 100–110 min (if finishing >2 hrs):

  • Optional Salt Cap for extra electrolyte support.

Post-Race Recovery

• Unived Elite Recovery Mix or Unived Endurance Protein

• Carb + protein in a 3:1 ratio for rapid glycogen resynthesis and muscle repair.

• Rehydrate with fluids and electrolytes.

Fueling Timeline at a Glance

Key Takeaways

• Target 50–60 g carbs/hour during the race.

• Alternate Gel 100 and Gel 180 to balance fast and sustained energy.

• Add Salt Caps around the 1-hour mark to maintain electrolyte balance.

• Prioritize recovery nutrition within 30 minutes post-race.

By following this strategy, you give your body the energy and hydration it needs to perform at its best.

References

1. Jeukendrup, A. E. (2010). Carbohydrate and exercise performance: the role of multiple transportable carbohydrates. Current Opinion in Clinical Nutrition and Metabolic Care, 13(4), 452–457.
2. Cermak, N. M., & van Loon, L. J. (2013). The use of carbohydrates during exercise as an ergogenic aid. Sports Medicine, 43(11), 1139–1155.
3. Hew-Butler, T., Loi, V., Pani, A., & Rosner, M. H. (2017). Exercise-associated hyponatremia: 2017 update. Frontiers in Medicine, 4, 21.
4. American College of Sports Medicine, Sawka, M. N., Burke, L. M., et al. (2007). ACSM position stand: Exercise and fluid replacement. Medicine & Science in Sports & Exercise, 39(2), 377–390.
5. Spriet, L. L. (2014). Exercise and sport performance with low doses of caffeine. Sports Medicine, 44(Suppl 2), S175–S184.
6. Jentjens, R. L. P. G., & Jeukendrup, A. E. (2005). High rates of exogenous carbohydrate oxidation from a mixture of glucose and fructose ingested during prolonged cycling. British Journal of Nutrition, 93(4), 485–492.