Fueling for the Long Haul: Half Marathon to 100 Miler
I have been getting a lot of questions about fueling lately and before I start let me state “I am not a registered dietician and you should connect with a nutrition professional for any specific guidance”. My goal here is to get you thinking, asking questions and learning.
When it comes to endurance events, fueling is often the difference between finishing strong and falling apart. Whether you're lining up for a half marathon or a 100-miler, how you fuel can determine the outcome of your day. But here's the truth: there’s no universal formula. Fueling is personal, and what works for one athlete might wreck another.
At On The Run Endurance, we don’t chase fads. We train real people with real lives—and fueling should match that mindset.
Common Fueling Approaches (and What to Consider)
There are several popular fueling strategies athletes gravitate toward. Each has its place, but none is perfect for everyone. Here's a breakdown:
The “Gel Every 30 Minutes” Method
Simple, structured, and easy to remember. This works well for athletes who can stomach highly concentrated carbohydrate products. But for others, it leads to gut distress, especially during longer events.
Pros: Easy to follow, efficient carb delivery
Cons: May cause GI issues, flavor fatigue, lacks electrolytes
Sports Drink Only
Some athletes prefer to drink their calories using high-carb hydration products. This can work in cooler conditions or shorter events, but balancing fluid intake with calorie and sodium needs becomes tricky.
Pros: Convenient, combines hydration and fuel
Cons: Risk of overhydration or under-fueling depending on sweat rate
Whole Food Strategy
Using things like bananas, dates, bars, or boiled potatoes can be easier on the stomach for some and better mimic daily eating habits. But they take more time to chew and digest, and aren’t always practical at race pace.
Pros: More natural, easier for some guts to handle
Cons: Bulky, slower digestion, hard to manage during fast segments
Mix-and-Match (Blended) Approach
Many experienced runners use a combination—maybe sports drink early, solid food mid-race, then gels or chews to finish. This allows for variety and flexibility, but takes thoughtful planning and testing.
Pros: Customizable, reduces monotony, balances energy and electrolytes
Cons: Requires gut training and organization, risk of overcomplicating
Fat-Adapted / Low-Carb Strategy
A niche but growing group uses low-carb training to become “fat-adapted” and rely less on sugar. More common in ultra-distance racing, it can reduce fueling needs but still requires carbs under higher intensity.
Pros: Less dependent on frequent fueling
Cons: High variability, harder to sustain at race effort
Tips from My Days Running Ultras
1. Eat on Race Day Like You Eat Every Day
If your day-to-day nutrition is clean, whole, and balanced, your race fuel should reflect that. Don’t suddenly start downing sugary gels every 20 minutes if that’s not what your stomach is used to. The long run is your testing ground—not just for pace, but for fueling strategy.
2. Fuel by Time, Not Distance
A lot of runners think, “I’ll take something every 4 miles.” But terrain, weather, and effort can turn 4 miles into 60 minutes—or 30. Time-based fueling ensures you stay ahead of the crash.
🔥 General Calorie Guidelines:
Half Marathon: 100–200 calories/hour (depends on duration and pace)
Marathon & Ultras: 200–300 calories/hour is a common target
For events over 4 hours, your body may tolerate more as intensity decreases
Use your long runs to practice this. Set a timer and treat fueling like your pacing—it’s part of the plan.
Takeaway: Stay ahead of your body’s needs—don’t wait until you’re depleted.
3. Don’t Sleep on Salt
Here’s where many endurance athletes come up short: electrolytes—especially sodium. When you’re sweating for hours, water alone won’t cut it. While many sports drinks contain sodium, they often don’t provide enough—or worse, they force you to drink more fluid than you actually need.
That’s why I’m a big believer in salt tablets or capsules. They let you separate hydration from electrolyte intake, giving you more control and customization based on your sweat rate, climate, and effort.
🧂 General Sodium Guidelines:
300–600 mg of sodium per hour for most endurance events
Some heavy sweaters or hot-weather athletes may need up to 800–1,000 mg/hour
Capsules typically contain 200–250 mg, making them easy to customize
You won’t replace everything you lose—but supplementing with a consistent sodium plan can help prevent cramping, nausea, and the dreaded energy fade late in a race.
Takeaway: Use salt capsules to fine-tune your sodium intake without flooding your stomach with fluid.
Final Word: Test Everything
Your fueling plan is part of your training. The best approach? Start with a simple structure, adjust based on your experience, and pay attention to how your body responds. Log what you eat, when you eat it, and how you feel. Over time, you’ll dial in a strategy that gives you confidence from the starting line to the finish.
Live What You Love,
~ Coach Dusty
