Scientists found a surprising way to make exercise work better

However, people with high blood sugar frequently miss out on some of these benefits from exercise, particularly improvements in how efficiently their bodies use oxygen. Elevated blood sugar raises the risk of heart and kidney disease. It can also interfere with the ability of muscles to increase oxygen uptake during physical activity.

For people facing this challenge, new research suggests an unexpected possibility. Instead of reducing fat intake, increasing it might help.

Keto Diet Study Shows Improved Exercise Response

A study led by exercise medicine researcher Sarah Lessard and published Feb. 25 in Nature Communications examined how diet affects exercise response. The team found that mice fed a high fat ketogenic diet experienced a drop in high blood sugar, also known as hyperglycemia. Their bodies also became more responsive to exercise.

"After one week on the ketogenic diet, their blood sugar was completely normal, as though they didn't have diabetes at all," said Lessard, associate professor at the Fralin Biomedical Research Institute at VTC Center for Exercise Medicine Research. "Over time, the diet caused remodeling of the mice's muscles, making them more oxidative and making them react better to aerobic exercise."

The ketogenic diet gets its name from ketosis, a metabolic state in which the body switches from using sugar as its main fuel to burning fat. Because the diet relies on high fat foods and severely limits carbohydrates, it contrasts with the low fat diets traditionally recommended by many health experts.

Potential Health Benefits of the Ketogenic Diet

Despite the debate surrounding it, the keto diet has been associated with health benefits for certain conditions, including epilepsy and Parkinson's disease. Historically, it was also used to manage diabetes. Before insulin was discovered in the 1920s, doctors sometimes relied on this approach to help lower blood sugar.

Lessard's earlier studies showed that people with elevated blood sugar often have reduced exercise capacity. This led her to explore whether a ketogenic diet could help restore the body's ability to adapt to exercise.

In the study, mice ate a high fat, low carbohydrate diet and ran regularly on exercise wheels. Over time, their muscles developed more slow twitch fibers, which are linked to greater endurance.

"Their bodies were more efficiently using oxygen, which is a sign of higher aerobic capacity," Lessard said.

Why Diet and Exercise Work Best Together

According to Lessard, exercise benefits nearly every tissue in the body, including fat tissue. But growing evidence suggests that the greatest improvements in health occur when diet and exercise are combined rather than treated as separate strategies.

"What we're really finding from this study and from our other studies is that diet and exercise aren't simply working in isolation," said Lessard, who also holds an appointment in the Department of Human Foods, Nutrition, and Exercise in Virginia Tech's College of Agriculture and Life Sciences. "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."

Future Research and Practical Diet Options

Lessard plans to expand the research to human participants to determine whether people experience the same improvements seen in mice.

She also points out that following a ketogenic diet can be difficult. For many people, a less restrictive eating plan such as the Mediterranean diet may be easier to maintain while still supporting healthy blood sugar levels. This approach includes carbohydrates from whole foods like fruits, vegetables, and whole grains instead of eliminating carbohydrates entirely.

"Our previous studies have shown that any strategy you and your doctor have arrived at to reduce your blood sugar could work," she said.