iFIT Trainer Ashley Paulson runs with a handheld water bottle, reflecting the hydration and fueling strategy covered in this guide.

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How ultrarunners fuel for races over 100 miles: Ashley Paulson’s nutrition strategy

When iFIT Trainer Ashley Paulson lines up for a 200 mile race, her nutrition plan starts working long before the starting gun. Fueling a body through two or three days of continuous movement takes a different kind of preparation than fueling a single hard workout, and most of that preparation happens months earlier, not on race morning.

Paulson built her nutrition approach over more than two decades of racing, including her Triple Crown season chasing the Tahoe 200, Bigfoot 200, and Moab 240 in a single year. Here is how she fuels before, during, and after races that push the body for days at a time.

Fueling in the week before a race

“You don’t gain fitness in race week,” Paulson says. “It’s all about showing up fueled, hydrated, and ready to roll.” Her race week focuses on extra carbohydrates and fluids, along with extra sleep, since an ultramarathon often means little to no sleep during the event itself.

At the Tahoe 200, that preparation showed up in her crew’s planning long before the start line. Her husband and crew chief, Matt, studied the entire 200 mile course to map out where drop bags and aid stations would fall, so Paulson’s nutrition and calories were already accounted for before she took a single step.

Training your gut before you train your legs

Paulson treats her digestive system the same way she treats her muscles, as something that needs gradual, deliberate training. “You wouldn’t go out and run 100 miles without building up to it, so why would you expect your gut to handle hours and hours of fueling without practice?” she says.

That approach lines up with what sports science has found. Gastrointestinal distress is common in endurance athletes, and “training the gut” through gradual, consistent fueling practice during training can improve stomach comfort and reduce symptoms of GI distress during exercise. [1]

Paulson practices with different products, textures, and flavors during training runs specifically because what tastes good at mile 10 can feel unbearable at mile 80. She recommends starting this process well before race day, since the gut, like the legs, needs time to adapt to new demands.

Hydration and electrolytes: why one size doesn’t fit all

“Hydration is not a one size fits all situation,” Paulson says. Sweat rate and sodium loss vary significantly between individuals, and her biggest piece of advice is to get a sweat test rather than guess.

That guidance tracks with current research on athletic hydration. Sweat testing can help estimate an individual athlete’s sweat rate and sodium loss to help guide a personalized hydration plan, though testing conditions and methods can affect how consistent those results are. [2] Because sweat composition varies so much between people, a hydration strategy built around someone else’s needs may not translate to another athlete’s body.

Paulson also cautions against overcorrecting with fluids. Her approach is to practice a hydration plan in training, under real conditions, long before race day.

When nothing sounds good: fueling through the low points

Every ultrarunner eventually hits a stretch where nothing appeals, and Paulson’s race day crew plans for exactly that moment. At the Tahoe 200’s mile 50 aid station, her husband Matt described the stop as a pit crew operation: “We’ve got her caffeine, her [protein shake], ketones. She has everything that she needs. We can repack her bag, swap her shoes really quick if we need to, and then just get her right back out.”

That kind of preparation matters because, as Paulson puts it, “what sounds amazing at mile 20 might sound absolutely disgusting at mile 150.” Her go-to options for the low points include a cold protein source when gels and sugar no longer sound appealing, along with simple, easy to tolerate carbohydrate sources she has already tested extensively in training. Her backup options are decided long before the race starts.

Nutrition mistakes first time ultra runners make

Paulson sees the same mistake trip up new ultrarunners again and again: going out without a real fueling and aid station plan. “People get caught up in the excitement, go out too fast, forget to eat, or assume they’ll just figure it out as they go,” she says. “At mile 70, when your brain is fried and nothing sounds good, that’s probably not the time you want to start making decisions.”

Her advice is to have a nutrition plan ready before race day, practice it extensively in training, and understand the course and weather conditions well enough to anticipate what each stretch will demand.

Recovery nutrition after the race

Recovery starts with eating. “First of all, I eat,” Paulson says. “After asking my body to do something a little crazy, it deserves some serious love.” Her first few days after a race focus on carbohydrates, fluids, and extra sleep, paired with easy movement like swimming or cycling rather than running.

She’s careful to separate feeling better from being fully recovered. “You don’t get stronger by just stacking miles forever,” she says. “You have to give your body time to absorb all that work.” For Paulson, recovery itself counts as part of training, not time away from it.

Frequently asked questions

How do ultrarunners train their gut for long distance fueling?

By gradually and consistently practicing fueling during training runs, using the same products, timing, and intake they plan to use on race day. This process can improve stomach comfort and reduce the risk of gastrointestinal distress during exercise. [1]

How do I know how much sodium I lose when I sweat?

A sweat test can help estimate your individual sweat rate and sodium loss, which can then be used to build a personalized hydration and electrolyte plan, though results can vary depending on testing conditions and methods. [2]

What should I eat during a long race when nothing sounds good?

Options that are easy to tolerate even when appetite is low, such as a cold protein source or simple carbohydrates already tested in training.

What’s the biggest nutrition mistake new ultrarunners make?

Not having a real fueling and aid station plan going into the race, which often leads to decision making mid-race at the exact point when it’s hardest to think clearly.

How should I eat in the days after finishing an ultramarathon?

Prioritize carbohydrates, fluids, and extra sleep, paired with easy, low-impact movement.

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References

National Library of Medicine. Training the Gut for Athletes
National Library of Medicine. Sweating Rate and Sweat Sodium Concentration in Athletes: A Review of Methodology and Intra/Interindividual Variability

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