{"id":19752,"date":"2025-12-16T11:32:41","date_gmt":"2025-12-16T11:32:41","guid":{"rendered":"https:\/\/www.scienceinsport.com\/sports-nutrition\/?p=19752"},"modified":"2026-03-18T16:52:18","modified_gmt":"2026-03-18T16:52:18","slug":"inside-the-science-of-gut-training","status":"publish","type":"post","link":"https:\/\/www.scienceinsport.com\/sports-nutrition\/inside-the-science-of-gut-training\/","title":{"rendered":"Inside the Science of Gut Training"},"content":{"rendered":"\n
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\n Written By<\/span>\n

Jonah Rosner<\/h3>\n

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6 Min<\/div>
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Inside the Science of Gut Training: How to Turn Your Stomach into a Performance Tool<\/h1>\n\n\n\n

For many marathon runners, it’s not the legs that give up first, it’s the stomach. <\/p>\n\n\n\n

Cramping, nausea, or that heavy, sloshing feeling can end a great race before the finish line.<\/p>\n\n\n\n

The idea that you can train your gut to handle more fuel might sound strange, but early research suggests it’s possible. You can train your gut, just like your legs.<\/p>\n\n\n\n

With practice, many runners learn to take in more carbs with fewer issues. The science is still growing, but the pattern is clear in studies and in real-world running: practice fueling in training, and race day goes better.<\/p>\n\n\n\n

If you’re training for a spring marathon, now’s the perfect window to start. Building your fueling tolerance over the next few months means your stomach will be as ready as your legs by race season.<\/p>\n\n\n\n

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WHY GUT TRAINING MATTERS<\/h2>\n\n\n\n

Your gut is part of your performance system. It doesn\u2019t only digest food. It moves fuel into your blood so your muscles can use it.<\/p>\n\n\n\n

During runs, carbohydrates are your body\u2019s fastest fuel. But your gut can only move so much energy into your bloodstream at once before it starts to complain.<\/p>\n\n\n\n

Training the gut may increase how effectively your body absorbs carbohydrates.<\/strong><\/p>\n\n\n\n

In animal studies, repeated carbohydrate feeding appears to improve how gut transporters move fuel into the bloodstream within days to weeks.<\/p>\n\n\n\n

A few human studies show similar trends after consistent practice.<\/p>\n\n\n\n

That means gut training probably helps in two ways:<\/p>\n\n\n\n

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  1. Physiological adaptation:<\/strong> your gut may become more efficient at moving carbs into your bloodstream.<\/li>\n\n\n\n
  2. Improved tolerance:<\/strong> your digestive system becomes more comfortable processing fuel while running.<\/li>\n<\/ol>\n\n\n\n

    Together, these may explain why runners who practice fueling often report fewer stomach issues and more steady energy, even though every runner responds differently.<\/p>\n\n\n\n

    In a small but landmark 2017 Monash University study, runners who practiced consuming 90 grams of carbohydrate per hour for two weeks reported fewer stomach problems and signs of better carbohydrate tolerance compared with those who didn\u2019t.<\/p>\n\n\n\n

    Other studies and countless athletes report the same pattern: practice reduces discomfort.<\/p>\n\n\n\n

    As researcher Jamie Pugh<\/strong> puts it, \u201cThe gut can adapt\u2014but we\u2019re still learning how trainable it really is.\u201d<\/em><\/p>\n\n\n\n

    HOW TO TRAIN YOUR GUT<\/h3>\n\n\n\n

    Gut training isn\u2019t a shortcut. It\u2019s a skill you build over time.<\/p>\n\n\n\n

    The goal isn\u2019t to reach a specific number, but to find the fueling rate your body can handle comfortably and consistently.<\/p>\n\n\n\n

    Here\u2019s a simple three-level framework to help you progress safely.<\/p>\n\n\n\n

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    Level 1: Novice (Building Phase)<\/strong><\/p>\n\n\n\n