One Major Side Effect Soda Has on Your Metabolism, Says Dietitian

 We're all familiar with the fact that soda isn't so great for our health. This fast-food favorite drink has been linked to a higher risk of obesity and numerous other health issues. (We've got a whole list of them right here.) But weight gain from knocking back too many sweet, fizzy drinks doesn't necessarily come down only to excess calories from sugar. In part, it may also have to do with how soda's sugars affect your metabolism.

You might (quite reasonably!) expect that caffeinated sodas would speed up your metabolism. It's true that caffeine is a stimulant that increases metabolic rate, so theoretically, sodas that pack a punch could boost your resting energy expenditure. Unfortunately, though, that's not the primary effect most sodas have on metabolism. Instead, their added sugars can actually slow your metabolism. 

How added sugars affect your metabolism

Here's where it gets interesting, though: Studies suggest that not all sugars are created equal when it comes to disrupting metabolism. Fructose, the sugar often used in soda recipes, appears to be a particular culprit. (The high fructose corn syrup in most sodas is about 55% fructose.) A 2012 study showed that people who drank fructose-sweetened beverages significantly decreased the number of baseline calories they burned daily. Translation: Their metabolism slowed, compared to people who didn't consume fructose-sweetened drinks.

When fructose goes through your digestive system, it ends up in your liver, where it gets converted to fat. This raises your triglyceride levels. Both weight gain from too many calories in soda and high triglycerides from too much fructose are hallmarks of metabolic syndrome. This cluster of metabolic symptoms puts you at greater risk of heart disease, diabetes, and stroke.

Sugary beverages are linked to a higher risk of disease.

In fact, some health experts have tied the rise of the obesity epidemic to a dramatic increase in soda consumption (and possibly the increase in fructose consumption). Whereas in the 1800s and early 1900s, the average American took in about 15 grams of fructose (mostly from fruits and vegetables), a 2008 study pegged the current number at 55 grams per day, with the largest source being sugar-sweetened beverages.

Diets high in fructose from soda and other foods like candy, juice, and maybe problematic beyond weight gain and slowed metabolism. As triglycerides from fructose build up in the liver, they can damage liver function or trigger fatty liver disease. And some studies have shown that high intake of fructose could lead to hypertension.

All this doesn't mean, of course, that a soda here or there will put your metabolism on the slow train to weight gain or land you with other health issues. But when you do choose to drink a can, enjoy it to the fullest—and let one be enough.