High-Carb Sports Nutrition May Be Quietly Accelerating Aging
For decades, athletes have been told to load up on carbs to avoid fatigue. But new research suggests that strategy may come with a cost: faster metabolic aging.
According to Andrew Koutnik, Ph.D., a researcher at Florida State University’s Institute of Sports Sciences and Medicine, fatigue isn’t caused by muscles running out of fuel. It’s driven by unstable blood sugar and reduced brain energy—factors closely tied to long-term metabolic health.
Why “More Carbs” May Be Aging Athletes Faster
Koutnik’s 2026 review found that many athletes consume far more carbohydrate than needed to sustain performance. For workouts lasting an hour or less, he says, carbs are often unnecessary. Even during longer sessions, as little as 10 grams of carbohydrate per hour may be enough—far below the standard 60–90 grams commonly recommended.
When carbs are overused, insulin rises, fat burning is suppressed, and the body becomes increasingly dependent on sugar for energy. Over time, that pattern mirrors what researchers see in early metabolic disease.
The Prediabetes Problem in Fit Athletes
From a longevity standpoint, the most concerning finding may be how quickly high-carb fueling erodes metabolic health. Koutnik and colleagues found that nearly 30 percent of lean, physically fit athletes following conventional high-carb sports nutrition guidelines developed markers of prediabetes.
Those athletes had higher fasting blood sugar, elevated insulin, and less metabolic flexibility, the ability to switch between fat and carbs for fuel. These are early warning signs linked to faster aging and higher chronic disease risk, and they’ve been reported even in elite endurance athletes.
The encouraging news: these markers often improve rapidly once carb intake is reduced.
Metabolic Flexibility Is a Longevity Marker
Koutnik’s data suggest athletes can perform just as well on lower-carb approaches when blood sugar remains stable. Lower insulin allows the body to access fat more efficiently, preserving metabolic flexibility.
That flexibility naturally declines with age, making fueling strategy less about maximizing output and more about preserving the metabolic systems that support healthy aging.
Longevity-Smart Fueling You Can Start Today
For athletes who want to stay strong, lean, and competitive for decades, Koutnik recommends three priorities:
- Protein is non-negotiable. Aim for up to one gram per pound of ideal body weight to protect muscle as anabolic resistance increases with age.
- Build meals around fiber. Leafy greens and non-starchy vegetables support gut health, inflammation control, and stable glucose.
- Use carbs strategically. Time them around demanding sessions and use the minimum amount needed to support performance.
To keep nutrition simple, CookUnity delivers chef-prepared meals straight to your door, making it easier to eat protein-forward, well-balanced meals at home—without defaulting to carb-heavy takeout or convenience foods.
Bottom line: fueling for longevity means protecting muscle, stabilizing blood sugar, and using carbs intentionally—so performance doesn’t come at the cost of long-term health.
Related: Here's What to Know About New U.S. Dietary Guidelines That Take Aim at Processed Foods