Let’s talk about something that so many people misunderstand: The Glycemic Index (and it’s partner Glycemic Load).
Has someone told you not to eat carrots because they are full of sugar? Many people quit eating them when the book “SugarBusters” came out. It had to do with the glycemic index (GI). As the low carbohydrate diet fad changed over time we began to hear more about Glycemic Index. Let me tell you what it is, along with the concept of glycemic load. I’ll show you why these concepts are not important to you achieving your goals and what to focus on instead.
First, what is the glycemic index?
Glycemic index, GI for short, rates carbohydrate containing foods for their effects on blood sugar level after consumption.
In short, how high does your glucose level rise and for how long. Depending on the food’s characteristics some foods enter the bloodstream fast and others slowly.
A food’s GI is ranked against a glucose solution on a scale of 0 to 100.
0-55 = Low
56-69 = Medium
70-100 = High
Foods with a higher GI produce a higher glucose response than low GI foods.
The Glycemic Index of a food depends on many factors:
- Differences in cooking process (e.g. boiling pasta for long time vs. al dente)
- Ripeness or variety of food (e.g. a ripe v. green banana or variety of potato)
- How long it takes the gut to digest (whole grain vs enriched)
- The size of the portion
In general, non-starchy vegetables, most fruits, milk, peas and beans tend to have a low GI. Carrots, on the other hand, have a high GI of 92. White bread, medium baked potatoes, and cornflakes also have high GI indexes.
Once you determine a food’s GI, then you can calculate the glycemic load of that food. Glycemic load (GL) considers both the GI plus the amount of carbohydrate you are eating. Both factors affect the glucose rise.
The GL= the food’s GI times the amount of carbohydrate in grams divided by 100.
For example: 1/2 cup of carrots GI 92 X 6g = 552 ÷ 100 = 5
Small baked potato GI 60 x 30g= 1800 ÷ 100 = 18
For GL
<10 is Low
11- 20 is medium
21 and over is high
In the examples, the carrots have a low GL and the small baked potato is in the medium range.
Remember that person who was told he couldn’t eat carrots? I remember feeling fortunate he came to me and I could send him back to his beloved carrots; those low calorie vegetables rich in beta carotene and vitamin A.
Clearing up confusing messages is one of my favorite things about being a RDN.
Anyway, you can see calculating GI and GL is rather cumbersome. Plus the GI and GL have nothing to do with the healthfulness of a food. A low GI food doesn’t mean it is high in nutrients.
Here are other limitations using GI:
GI is based on an individual food, but we usually eat several foods at once. Every combination affects the GI and GL.
For example, eating protein and fats at the same time affects the GI.
Putting butter on toast lowers the GI.
People have individual responses to GI.
There is no evidence that GI affects A1C or weight.
So what should you do?
Instead of trying to live your life according to the Glycemic Index you will get more “bang for your buck” following these tips:
Focus on healthy food and balanced meals. Include fiber-rich whole grains, fruits and vegetables, lean protein, and low-fat or fat-free dairy. Balanced meals will be satisfying and provide the variety of nutrients your body needs.
Eat regular meals and have a healthy snack in-between if you get hungry. Skipping meals can lead to overeating later.
All fruits and vegetables are healthy and most Americans don’t get enough. Eating different colored fruits and vegetables is a simple way to ensure you are getting variety of essential nutrients.
If you have diabetes eat carbohydrate in the right size portions spaced throughout the day. The amount of carbohydrate has the most impact on your glucose response. Some people count carbohydrates, or use the “plate method” to get a consistent amount.
Note: According to the folks at Diatribe there are 42 factors that can affect your glucose when you have diabetes? It’s is difficult to figure out the exact cause of a spike. If you notice that a specific food seems to raise your glucose above your target every time, it is possible that it is related to your body’s response to the food’s glycemic index.
If you want to modify the rise in your glucose level, try eating a smaller serving and make it part of a mixed meal with protein and fat and see what happens. Make sure you enjoy every bite! Remember sometimes your glucose will be above the target despite your best efforts. If you are concerned about yours please talk to your health care provider for guidance.
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