What is the Glycemic Index and why should you care?

Good carbs, bad carbs. Slow carbs, fast carbs. What’s the difference and does it even matter when you are trying to follow a low-carb lifestyle?

There has been much written about carbohydrates and how to limit them over the last several years. Starting way back in the early 2000s with the Adkins diet, low-carbohydrate eating has recently become the hottest topic in human nutrition. With advocates of “Keto,” “Paleo,” and “Mediterranean” style diets all clamoring for your attention, it has become increasingly difficult to figure out which diet may be best for you.

Most scientists now agree that limiting refined and processed sugars in your diet is advisable for pretty much everyone. The difficult part is knowing how much or how severely we should limit our carbohydrates in general.

Certainly, the answer to this question should be unique to each individual. However, there are some pretty significant hard and fast guidelines we should follow regardless of whether we are looking to lose weight, normalize our glucose and insulin metabolism, or simply feel better in our daily lives.

How, then, to judge between different types and sources of carbohydrates in our diet. Probably the most useful tool for (relatively) objectively measuring the difference between carbohydrates is the Glycemic Index.

The Glycemic Index is a ranking system that, well, ranks carbohydrates using a numeric system. Foods are given a value, generally between 50 and 100. Carbohydrates with a lower Glycemic Index value are generally absorbed and metabolized more slowly than foods with a higher value. As such low Glycemic Index (GI) foods cause a lower and slower rise in blood glucose, and therefore in blood insulin levels.

High GI foods are absorbed and metabolized quickly, thereby causing a steep and high rise in blood glucose (and subsequently blood insulin) levels. It is believed that these foods contribute more vigorously to the development of insulin resistance than low GI foods.

To make matters just a bit more convoluted, a single type of food can have more than one GI value. Various factors such as freshness and ripeness of fruits and vegetables (green bananas have a lower GI than ripe bananas), cooked vs. raw (cooking foods usually raises the GI), and preparation (the longer you cook pasta, the higher the GI) can all affect a particular food’s likelihood of raising your blood glucose.

In addition, the combination of foods eaten together may have an effect. Combining high Glycemic Index food with low GI foods will lower the overall glycemic index of the meal.

In general, and as you might expect, sugary food and sweets have the highest GI, while “white” starches (bread, potatoes, rice) are also quite high. Green vegetables and meats have the lowest GI values, and fruits fall somewhere in the middle.

If you are serious about lowering your blood glucose and insulin levels, become aware of the glycemic index of the foods that you eat. With all the variables mentioned above, it might be a good idea to look into one of the various free apps out there for determining GI (Glycemic Index, Load Net Carbs is a good one that is also free.)

With a little bit of investigation and being intentional about your diet, you can lower the Glycemic Index of your diet and watch your blood glucose levels follow suit.