Sugary drinks can change your muscles in just one month

That cold soft drink sure tastes good on a hot day, right? Maybe that energy drink hits the spot after a long workout too. But we know that too much sugar isn’t so great for us. You probably know it rots your teeth if you’re not careful. You also probably know that sugary drinks can influence your metabolism so that you could run into trouble with how insulin works in your body, possibly increasing risk of developing type 2 diabetes.

But did you know sugary drink consumption that it can also influence how your muscles function? In this study published in the European Journal of Nutrition, it appears that people given an average of 760mls of sugar sweetened drink (Lucozade Energy) every day for 4 weeks showed significant changes in how their muscles used fuel sources. Specifically, their muscles seemed to be able to sense the high sugar nature of their new environment (the participants were selected because they would not usually drink more than 500ml of sugary drinks per week), and changed their functioning to prefer burning sugar instead of fat. This also seemed to influence future functioning of muscles too.

Although it is quite a technical paper, the authors make a good argument that these changes can lead to a reduced ability of our muscles to burn fat, and instead we gain it. They also argue that the body becomes less able to cope with increases in blood sugar levels. Our body adapts to the new sugary environment it finds itself in which leads to changes in gene expression in our muscles. These are the kinds of unhealthy metabolic alterations seen in people with weight problems and type 2 diabetes.

From a performance point of view, especially for endurance athletes, there’s a warning here about how what we drink can influence how your muscles adapt and perform when you run, bike, kayak or swim. Just 760mls of Lucozade Energy a day over 4 weeks. That’s two bottles. Maybe not everyone is drinking in that much sugar, but perhaps more than we would ideally like – especially if you are exercising regularly (though a previous post gives good reasons as to why you don’t need to drink anything other than water if you’re exercising for less than an hour at a time).

If your muscles change so that they start to prefer sugar over fat, this is going to have an impact on your fueling strategy during events, and on how you feel when your body starts to run out of readily accessible sugars. If your muscles are ‘trained’ out of using fat as a fuel source, I think we could expect to see some serious bonking and inefficiency as those sugars get depleted.

Let me know what you think, especially any nutritionists who happen to read this post.

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