Everyone Says Sugar is Bad for You. What is Sugar Anyway?

Dr. Linda Dahl
7 min readOct 6, 2022

A simple explanation of monosaccharides and complex carbohydrates

Everyone knows eating too much sugar is bad for you. It makes you fat. It causes diabetes, fatty liver, depression, acne, and hastens the aging process. It’s even addictive. The FDA now decided it is also concerned about your sugar intake. It recently proposed a new rule requiring foods that call themselves healthy have less than 2.5 grams of added sugar. That advice may seem straightforward enough to follow. If you want to know how much sugar is in something, you can just look at the label, right? It’s actually not that easy. Sugar, just like a spy, comes in many forms and goes by many different names. And not every food comes with a label. Come to think of it, what is sugar anyway? And how is “added sugar” different than regular sugar?

Before getting into the sweet science of sugars let’s back it up a bit and talk about why food is considered food. The short explanation is that food is something our bodies can break down and use for things like fuel and making new cells, etc., and it also won’t kill us (although the killing us part is debatable when it comes to sugar).

That’s a pretty broad definition, so to narrow it down even further, the breakdown products of said food should fall into one of the three categories of macronutrients (For simplicity, I’m ignoring micronutrients, like vitamins and minerals).

  1. First, we have proteins. These are chains of amino acids that fold into three-dimensional shapes and act as building blocks. They are found in things like meat, fish, beans, and soy.
  2. Then there are fats–the oily stuff found in nuts, olives, avocados, dairy, and so forth that store energy and help make things like hormones.
  3. Finally, there are carbohydrates. This is where sugar comes from.
Photo by D koi on Unsplash

To appreciate the science behind carbohydrates, let’s go back to your high school biology class. Close your eyes and imagine you’re a teenager. (If you’re as old as I am, it’s the 1980s, and your hair is backcombed within an inch of its life into a lofty…



Dr. Linda Dahl

Physician. Author of Tooth and Nail:The Making of a Female Fight Doctor & Better Breastfeeding, http://www.drlindadahl.com @doctorlindadahl