The diet also changed the structure of the animals’ muscles over time. Researchers observed that the muscles developed more oxidative properties and responded better to aerobic exercise
A new study suggests that eating more fat, rather than less, may help the body gain greater benefits from exercise when blood sugar levels are high, offering a fresh perspective on the interaction between diet and physical activity.
The research, led by exercise medicine scientist Sarah Lessard at Virginia Tech, found that a ketogenic diet helped normalise blood sugar levels in mice and significantly improved how their muscles responded to exercise. The findings were published in the journal Nature Communications.
Exercise is known to improve the body’s ability to absorb and use oxygen—a key marker of long-term health and longevity—while also helping control weight, strengthen the heart, and build muscle. However, elevated blood sugar, or hyperglycemia, can blunt these benefits, particularly improvements in oxygen uptake during workouts. Hyperglycemia is also linked to higher risks of heart and kidney disease.
In the study, mice with high blood sugar were placed on a ketogenic diet, which is high in fat and extremely low in carbohydrates. Within a week, their blood sugar levels returned to normal. “After one week on the ketogenic diet, their blood sugar was completely normal, as though they didn’t have diabetes at all,” Lessard said.
The diet also changed the structure of the animals’ muscles over time. Researchers observed that the muscles developed more oxidative properties and responded better to aerobic exercise. Mice that exercised regularly on running wheels developed more slow-twitch muscle fibers, associated with greater endurance and more efficient oxygen use, indicating higher aerobic capacity.
Ketogenic diets push the body into ketosis, a metabolic state in which fat rather than sugar becomes the main source of energy. While low-fat diets have traditionally been recommended, ketogenic approaches have long been used to manage conditions such as epilepsy and Parkinson’s disease and historically were employed to help control diabetes before insulin therapy became available in the 1920s.
Lessard emphasised that diet and exercise are not independent strategies. “There are a lot of combined effects, and we can get the most benefits from exercise if we eat a healthy diet at the same time,” she said.
The team plans to expand the study to human participants to see whether the same metabolic improvements occur outside laboratory conditions.
