A blogger calling himself The Renegade Pharmacist published an infographic appearing to show how a single can of soda effects you over the course of an hour, and naturally the Internet went wild with the thing.
We’re not endorsing the science, but we did think it was worth a closer look. And while we’re for the most part okay with caffeine—it can do some good for your workouts, actually—it’s worth asking exactly why sugar hits your system so hard.
The answer is simple: insulin.
Foods containing a lot of sugar but little protein or fat are said to have a high glycemic index, meaning the sugar rapidly releases into your bloodstream. Pure processed sugar (i.e. the stuff in most name-brand soda) is about as high as you can get on the ranking. A 12-ounce can of Coke contains 39 grams of sugar, according to Coca-Cola, while a can of Pepsi contains 41 grams.
When you eat or drink something with a high glycemic index, your pancreas starts cranking out insulin to help process the sugar and control your blood sugar levels. But a sugar surge like that from a soda causes a big spike in insulin, which causes your blood sugar levels to hit rock bottom, potentially leaving you shaky, weak, and, yes, hungry.
It also has debilitating long-term effects on your health: If your intake of excess sugar—in the form of sodas, candy, junk food, etc.—makes up 25% of your daily calories, you have twice the risk of dying from heart diseaseas someone whose intake is just 7%, a study of more than 30,000 Americans found.
It’s not just soda, of course: Plenty of foods are sneaky sugar bombs, from barbeque sauce to some sports drinks.
On the other hand, natural, unprocessed sugar in fruit is accompanied with nutrients and fiber, which control the release of sugar into the bloodstream and prevent the insulin dump. But without those stabilizing factors, sugar hits the system hard.