When you have high blood sugar, your muscles struggle to get the most from exercise. They still work, but your body doesn't adapt as efficiently — your aerobic capacity doesn't improve the way it should. A new study suggests an unexpected fix: eating more fat, not less.
Researchers led by exercise medicine scientist Sarah Lessard at Virginia Tech fed mice with high blood sugar a ketogenic diet — high fat, very low carbohydrates. Within a week, their blood sugar normalized completely. Over time, their muscles physically remodeled, developing more slow-twitch fibers built for endurance and becoming far more efficient at using oxygen during exercise.
"After one week on the ketogenic diet, their blood sugar was completely normal, as though they didn't have diabetes at all," Lessard said. "Over time, the diet caused remodeling of the mice's muscles, making them more oxidative and making them react better to aerobic exercise."
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Start Your News DetoxThe ketogenic diet works by shifting your body into ketosis — a metabolic state where fat becomes your primary fuel instead of glucose. It's a radical departure from decades of "eat less fat" messaging, which is partly why keto remains so polarizing. But it's not entirely new territory. Before insulin was discovered in the 1920s, doctors used ketogenic diets to treat diabetes for exactly this reason: it lowers blood sugar.
Diet and exercise aren't separate strategies
Lessard's team observed something important: people with high blood sugar typically have reduced exercise capacity. The question became: could shifting how your body burns fuel actually enhance how it responds to physical activity?
To test this, they gave mice a high-fat, low-carb diet and access to running wheels. The animals developed greater endurance capacity and more efficiently used oxygen — a marker of genuine aerobic improvement. The key finding wasn't just that blood sugar dropped. It was that diet and exercise appeared to work together, amplifying each other's effects.
"What we're really finding is that diet and exercise aren't simply working in isolation," Lessard noted. "There are a lot of combined effects, and so we can get the most benefits from exercise if we eat a healthy diet at the same time."
The catch: ketogenic diets are hard to maintain long-term. Lessard acknowledged this limitation and suggested that less restrictive approaches might work just as well in practice. The Mediterranean diet, for example, includes carbohydrates from whole grains, fruits, and vegetables while still helping control blood sugar. "Our previous studies have shown that any strategy you and your doctor have arrived at to reduce your blood sugar could work," she said.
The research is currently in mice, but Lessard is planning human trials to see if the same muscle remodeling happens in people. If it does, it could shift how doctors approach exercise recommendations for people with high blood sugar — not as a standalone strategy, but as part of a coordinated dietary and physical approach.
