Everything you need to know about the glycemic index

The glycemic index is the best way to determine which foods can help lower your blood sugar. Here's how it works.

To figure out which carbs are best and worst for blood sugar, scientists had to do some serious detective work. First, they needed to come up with a way to measure a food's effect on blood sugar. glycemic index (GI) was developed back in 1981 (the prefix glyc- means "sugar").

• For this study, volunteers eat different foods, all containing 50 grams of carbohydrate. Then researchers measured the volunteers' blood sugar over the following two hours to see how high it went.
• As a control, the researchers used pure glucose, the form of sugar that's identical to blood sugar — your body converts glucose very quickly to blood sugar — and assigned it the number 100 on a new index.
• The glycemic index opened a lot of eyes. Almost everyone had assumed that table sugar would be the worst offender, much worse than the "complex carbohydrates" found in starchy staples such as rice and bread. But this didn't always prove true.
• Some starchy foods, like potatoes and cornflakes, ranked very high on the index, raising blood sugar nearly as much as pure glucose. That's why you won't find them listed in recipes that aim to improve blood sugar stability.
• The higher the glycemic load (GL) in the diet, the greater the incidence of obesity, diabetes, heart disease and cancer.

Carbohydrates consist of starches and sugars.

• Starch — think of starchy foods like beans and potatoes — is made up of sugar molecules bound together in long chains. When you eat a carbohydrate-rich food, your body converts those starches and sugars into glucose, or blood sugar.
• Some starches, like those in white rice, are extremely easy for the body to convert, and therefore blood sugar levels rise like a hot temper after you eat them.
• Others, like those in beans, take a lot more work to break down, so blood sugar levels simmer rather than explode.

Overall, the glycemic index is a handy guide that can help you manage diabetes and control your blood sugar through healthy dieting. Just remember to consult your doctor before making any major dietary changes.