Run Smart: Dr. Hazel Wallace’s Secrets to Fueling for a Half Marathon

Dr. Hazel Wallace, a.k.a The Food Medic, shares her secrets to fueling up for a half marathon, proving that even shorter races need a smart nutrition game plan to help you crush those 13.1 miles feeling strong and energized.

When it comes to running, advice on fueling for marathons or ultra-races is everywhere. Blogs, forums, and experts all have something to say about how to prepare for those grueling distances. But what about half marathons? It’s easy to think that 13.1 miles (or 21 kilometers) isn’t as demanding, so nutrition might not seem like such a big deal. After all, it’s not a full marathon, so does it require the same level of attention to diet and fueling?

It does. Proper nutrition is just as crucial for a half marathon as it is for longer races. If you want to perform your best and feel good during the race, you need to think carefully about what you eat before, during, and after the run and find the fueling strategy that works for you. Dr. Hazel Wallace, a seasoned runner and expert in both medicine and nutrition, is here to explain why.

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Hybrid doctor and nutritionist

Hazel knows a thing or two about nutrition and movement. She’s a medical doctor, a registered associate nutritionist, and a personal trainer. Her journey into the world of nutrition started while she was studying medicine at the University of Cardiff. Like many medical students, she was curious about how lifestyle choices – especially diet and exercise – could impact health. But rather than just sticking to what she learned in lectures, she decided to dive deeper. She started a blog called The Food Medic to share her insights with others. “I wanted to translate the science to easy, actionable steps that I could share on my blog and on social media,” she says.

Her blog quickly grew in popularity, and alongside her medical career in the NHS, Hazel continued to expand her knowledge. She went back to university to study nutrition more formally and became a hybrid expert in both medicine and nutrition. Fast forward 12 years, and Hazel has published three books on sports, health, and nutrition. The Food Medic has transformed into a thriving website full of easy-to-follow tips on evidence-based nutrition and health information.

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 “If you look at my content, it’s not about extremes or restrictions, it’s very much about balance and finding ways of moving your body that’s enjoyable,” Hazel explains. “It’s about finding ways of reducing salt intake, and adding more vegetables and fiber to your diet in ways that are enjoyable.”

Hazel’s philosophy is simple: “It’s about making nutrition easy and sustainable.” It’s not about following a strict diet or cutting out entire food groups. Instead, it’s about making small, manageable changes that you can stick to long-term. “Ultimately, I don’t think there is a single best diet. People are often looking for a quick fix or a magic pill but I’m always preaching that balance and everything in moderation is best. For instance, it’s fine to have chocolate and a glass of red wine now and then.”

Why nutrition matters for a half marathon

“I’m running ‘The Great North Run’ in Newcastle this year, the world’s biggest half marathon and I’m really looking forward to it,” Hazel shares, brimming with excitement.

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Ahead of her race, Hazel knows that even shorter running distances require careful planning. “Sports nutrition is different from general nutrition advice. It can make or break your performance even if it’s ‘just’ a half marathon.”

One of the key differences between sports nutrition and everyday nutrition is the focus on carbohydrates. Carbs are your body’s primary source of energy, especially during endurance activities like running. “In the lead up to The Great North Run, like two or three days out, I will start gradually increasing my carb intake. Carbs are your friend when it comes to fueling pre-run.”

Carb loading isn’t just for marathon runners. Even for a half marathon, increasing your carbohydrate intake in the days leading up to the race can help ensure that your muscles are fully stocked with glycogen – the stored form of glucose that your body uses for energy. This can help you avoid hitting the dreaded “wall” during the race, where your energy levels suddenly plummet, and every step becomes a struggle.

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On top of carb loading a few days out from the run she also recommends runners “don’t try any new foods two or three days out from your race because you never know what’s going to happen on race day.” This is crucial because the last thing you want is to have an upset stomach or digestive issues while you’re running. 

The morning of the race and race day

“I eat the same breakfast before every run,” she shares, “because it works for me. I eat a bagel with peanut butter and jam. I know it sits well with me and it doesn’t affect my gut. It’s not high in fiber, it doesn’t weigh me down, it offers quick-acting carbs. I have that with a coffee and some electrolytes every single time.”

Why this combination? It’s all about finding something that provides the right balance of energy without causing any digestive distress. The bagel offers easily digestible carbs, while the peanut butter adds a bit of fat and protein to help keep her feeling full. The coffee gives her a caffeine boost, which has been shown to improve endurance performance, and the electrolytes help ensure that she’s properly hydrated.

As for what she takes during her race: “I’ll start taking some gel 45 minutes into my run and then roughly every 30 minutes after that,” Hazel shares. Even though a half marathon is shorter than a full marathon, it’s still important to refuel during the race.

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“What you want to do is get around 30 grams of carbs every 30 minutes, or 60 grams every 60 minutes. More trained runners might take more on, but I find that amount and timing works for me.”

Hydration is another critical aspect of race day nutrition. While it’s essential to stay hydrated, Hazel warns against drinking too much water: “My advice is to drink to thirst. You don’t want to be guzzling down loads of water but you also don’t want to do the entire race without drinking any water either.”

Hazel’s top piece of advice for half marathon runners is simple: Don’t underestimate the distance. “Ultimately, I would say don't do your run unfueled, especially if you're not a super experienced runner. I think a lot of people see the half marathon distance as a distance that is not as significant as a marathon, but it's still a very long way.”

Her final tip? “Definitely bring fuel with you and find what works best for you.”

Hazel will be running The Great North Run on Sunday 8 September, alongside 60,000 other runners, where the atmosphere is sure to be electric, with the northern spirit of Newcastle shining through. If you spot her on the course, she might just share a tip or two on her fueling wisdom as you run alongside her. And who knows? With the right preparation and nutrition, you might just surprise yourself with how well you perform.