Sucrose

Also known as table sugar to you and me, it’s the granular stuff in Grandma’s apple pie, the lump or two you add to your coffee, the fine white powder that’s dusted over a deep-fried funnel cake. It’s a slightly complicated molecule, so our bodies don’t really want to have to deal with it. In fact, within seconds of sucrose hitting our intestines, our enzymes split it into two separate molecules: glucose and fructose.

Glucose

This is simple sugar found in all carbs that is used immediately by our bodies for energy or stored in the muscles and the liver as glycogen. That’s the stuff that shoots directly into the bloodstream and causes our pancreas to pump out insulin; insulin pulls it out of the bloodstream so the body can use it, and if there’s too much of it, stores the excess as fat.

Fructose 

The most problematic type of sugar healthwise. The body can’t really use fructose for energy—at least not right away. Fructose is instead shuttled to the liver, where it’s metabolized and stored as fat. This process causes spikes in the hormone ghrelin, the “I’m still hungry” hormone that sends us out seeking additional calories. Fructose may increase blood pressure, increases heart rate, and boosts myocardial oxygen demand (basically, how much oxygen your heart needs to function). It may also contribute to inflammation, insulin resistance, and overall metabolic dysfunction. And we get more fructose in our diets today than was ever possible before thanks to high-fructose corn syrup, the sweetener used in soda and most other convenience foods.