The glycemic index is gaining a lot of speed as a new health trend. We are seeing more and more articles about it, and many new diet and weight loss programs are using the concept.
So, what is the glycemic index?
The Glycemic Index, or GI, measures how high your blood sugar rises after eating 50 grams of a carbohydrate. The more quickly you absorb the carbs from a particular food, the more quickly your blood sugar rises and your body responds with insulin, and the higher that food's GI value; a lower GI number means that a food has a slower absorption rate, resulting in lower blood sugar and insulin response.
For the most part, higher-GI foods tend to be high-sugar and refined products like white bread. The lower-GI foods include more whole grain products, fruits, and vegetables.
But it isn't as straight forward as it sounds. The GI number is based on eating just that one food. But we typically don't sit down and eat several slices of bread or a cup of rice. Most often we are eating them in combination with other foods. Once you add in other foods -- other carbs, fats, and proteins -- the GI of that entire meal will change.
Protein and fat can alter the absorption time of carbs, and the way the foods are prepared can affect absorption rate and GI numbers as well (for example, pasta cooked al dente have a lower GI than well- cooked noodles, and a fully ripe banana will have a higher GI than a green, unripe one).
The GI index is great as a general guideline, but nothing about it is black or white. For example, carrots are a high GI food, but you won't have a large blood-sugar spike and gain weight because you had some on your salad (despite what many fad diets may tell you). The fact that they're high GI isn't a reason to avoid carrots. Think about it this way: In order to eat 50 grams of carrots, you would need to eat 10 cups in one sitting. You'd have to really love carrots to accomplish that.
For a more accurate picture, figure out a food's Glycemic Load. This is based on the amount of carbohydrates in a typical serving size of any given food. The Glycemic Load allows us to get a clear picture of what eating a serving of carrots or watermelon is or is not going to do. To find a food's Glycemic Load, use the following equation:
GI value of a food x number of carbohydrates per serving = Glycemic Load
You can look up the Glycemic Load of many foods at Harvard Health's site by clicking here.