The glycemic index (GI) is a way to measure the impact specific types of food have on blood sugar. GI values range from zero to one hundred. Food with a high GI value will make blood sugar levels rise (and fall) quickly, food with a low GI value will have a more slow and steady effect.
A GI value under 55 is low; foods that have a low GI value include beans, cruciferous vegetables, grapefruit, and tomatoes. A GI value between 56-69 is moderate; examples include pasta, green peas, sweet potatoes, orange juice, and blueberries. A GI value over 70 is high; examples include refined sugar, potatoes, white bread, dried fruit, carrots, and watermelon.
Why Are Glycemic Values Important?
Paying attention to the GI values of the food you eat allows you to exert a level of control over your blood sugar; there are many reasons why this is desirable.
Persons with diabetes struggle with maintaining balanced blood sugar. It’s a disease that’s reached epidemic proportions. Over 29 million Americans have diabetes, almost 90 million more are prediabetic. A diet centered around foods with a low GI value can help keep blood sugar under control.
You don’t have to suffer from diabetes to experience the benefits of regular, balanced blood sugar. Studies suggest consuming low GI food may help prevent cardiovascular disease and cancer; and that barely scratches the surface when considering the revelations uncovered by research into the effects of a low GI diet:
- A low GI diet may reduce the risk of type 2 diabetes.
- A high GI diet is associated with an increased risk of cardiovascular diseases.[6, 7]
- A study published in the American Journal of Clinical Nutrition in January 2016 suggests that following a high GI diet increases the risk of depression.
The Relationship Between Blood Sugar and Carbohydrates
Simple carbohydrates, also known as monosaccharides or disaccharides, are digested quickly and have an immediate effect on blood sugar. Common examples include refined sugar or high fructose corn syrup, as found in soft drinks. In general, foods high in simple carbohydrates have a high GI value.
Complex carbohydrates, also known as oligosaccharides and polysaccharides, are metabolized more slowly and do not have a dramatic effect on blood sugar. Foods high in complex carbohydrates include whole grain bread, vegetables, and legumes. Complex carbohydrates usually have a low GI value and, additionally, accompany other nutrients (such as fiber, vitamins, and minerals) that further reduce digestion time.
The Best Low Glycemic Index Foods
Below is a list of various foods and their GI value, as well as their glycemic load value–something we’ll cover shortly.
|Food||Glycemic Index (glucose = 100)||Total Serving Size (grams)||Glycemic Load Per Serving|
What Is Glycemic Load?
It’s easy to think that all high GI value foods are best avoided since high blood sugar is associated with so many problems, but portion size needs to be considered as well.
For example, carrots have a high GI value but a typical serving of carrots only contains about 6 grams of carbohydrates; probably not anywhere near enough to upset the blood sugar of the average person.
This is where glycemic load enters the picture. The glycemic load provides a more thorough consideration of the impact food has on blood sugar because it takes into account the GI value as well as the grams of carbohydrates (fat and protein are not considered as they do not affect blood sugar) in a serving.
Calculating Glycemic Load
Glycemic load is calculated by multiplying the GI value by the grams of carbohydrates in a serving and dividing by 100. A glycemic load value of 10 or less is low; 20 or above is high.
Watermelon, for example, has a GI value of 72 although a typical serving of watermelon only provides 6 grams of carbohydrates; a quick calculation reveals a glycemic load of less than 5.
A can of soda, on the other hand, may have a GI value of 65 but if a single can provides 40 grams of carbohydrates that means the glycemic load is 26, which is very high.
Is it any wonder that steady, daily consumption of soda and other sugary beverages contributes to so many health problems?
Factors That Affect Glycemic Index Values
Keep in mind that the GI value is just a starting point and can be affected by a number of factors. Processing and refining, for example, will result in a higher GI value. A whole baked potato has a lower GI value than instant mashed potatoes; processed orange juice has a higher GI value than fresh squeezed.
Eating different foods together can affect GI values. Research has shown that the negative effects of a high-carbohydrate diet are lessened when consumed with fiber. (Just to ensure there’s no confusion — no, eating a pound of lettuce won’t cancel out eating a pound of sugar.) The more ripe a fruit or vegetable, the higher its GI value. And, individual physiology–age, metabolism, health conditions–affect the way blood sugar is influenced.
Incorporating a Glycemic Diet Into Your Life
When constructing your diet, glycemic index and glycemic load values are great tools for guidance but need to be balanced with fundamentally sound principles of nutrition:
- Eat a variety of real, whole, organic food.
- Avoid junk food, refined sugar, and empty calories.
- If you splurge, do so in moderation.
- Quench your thirst with purified water.
Have you made a concerted effort to consume more low GI value foods and fewer high GI value foods? What tips can you share for designing a meal plan? What benefits have you noticed? Leave a comment below and share your thoughts with us.
by Dr. Edward Group DC, NP, DACBN, DCBCN, DABFM
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