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Eating These Two Things May Be Ruining Your Workout Progress, Study Says

A new study discovered that eating a lot of sugary, processed foods can hinder your body's ability to become fit.
tired girl sitting on grass

For some, it seems obvious that eating foods riddled with sugar and other nonnutritive sweeteners, additives, and preservatives would have a negative impact on our overall health over time. Others, however, may have a different opinion.

Have you ever heard someone say they'll just exercise a little more after eating something that was loaded in sugar and unhealthy fats, such as a pint of ice cream? This mentality of working out more to burn off the extra calories you ate may work from time to time, but if eating pints of ice cream is habitual, it could prevent you from improving your physical fitness.

While past epidemiological studies have identified links between these blood sugar levels and fitness, they've never answered one key question: Which one paves the way for the other, high blood sugar or low fitness? A new study published in the journal Nature Metabolism unveiled an interesting relationship between these two conditions by exploring the effects diet had on the rodent's endurance.

There were three groups of adult mice in the study. The first group went from eating normal chow to one that comprised a lot of saturated fat and sugar. The second group was fed normal chow but was injected with a substance that reduced their ability to produce insulin, which helps to stabilize blood sugar levels. After four months, both the first and second groups developed high blood sugar, whereas the third group was only given normal chow to eat and remained as the control group.

Researchers then monitored each group's physical fitness progression by measuring how long they could run on a treadmill before becoming completely exhausted. In addition, they placed a running wheel in each mouse's cage and let them exercise as they pleased for a month and a half. Each mouse ran about 300 miles on average, however, the fitness levels among all three groups looked starkly different.

The groups of mice with high blood sugar showed little no improvement on their physical fitness test, whereas the control group could run for much longer on the treadmill than they were able to prior to running on the wheel for six weeks. Scientists discovered that the control group had developed new muscle fibers as well as new blood vessels, which aid in transporting oxygen to the muscles. The mice with high blood sugar levels, on the other hand, developed deposits of collagen in their muscle tissue, which effectively obstructed new blood vessels from forming.

The researchers then checked a group of 24 human adults' endurance and blood sugar levels and found similar outcomes as the mice. Those who had the worst blood sugar control also had the weakest endurance because, after exercise, their muscle tissues had a high activation of proteins that prevented the formation of healthy blood vessels.

In short, a diet high in sugar and heavily processed foods may be inhibiting you from reaching your fitness goals—no matter how many hours you spend exercising each day.

Cheyenne Buckingham
Cheyenne Buckingham is the news editor of Eat This, Not That!, specializing in food and drink coverage, and breaking down the science behind the latest health studies and information. Read more
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