Should You Worry About High Glycemic Index Foods?

Evaluating foods solely based on their Glycemic Index (GI) can be misleading and does not provide a complete picture of their health impact.

Here’s a more nuanced look at why this is the case and how to better evaluate foods for a healthy diet and we will help you understand this concept using coke and watermelon as examples.

Understanding Glycemic Index (GI)

The Glycemic Index measures how quickly a carbohydrate-containing food raises blood glucose levels. Foods are rated on a scale from 0 to 100, with higher values indicating a faster increase in blood glucose.

While the GI can be useful for understanding how different foods affect blood sugar levels, it is only one part of the picture.

It is grouped as high, medium and low glycemic index foods –
1. Low GI Foods – 1 to 55
2. Medium/moderate GI Foods – 55 to 69
3. High GI Foods – 70 and higher

Factors to Consider Beyond GI

1. Glycemic Load (GL):
   • Glycemic Load takes into account the quantity of carbohydrates in a serving of food, providing a more accurate representation of its impact on blood sugar. GL is calculated by multiplying the GI by the carbohydrate content per serving and then dividing by 100.

Coke vs. Watermelon: A Comparison

• GI Values:
  • Coke: GI of 63
  • Watermelon: GI of 72
• Carbohydrate Content:
  • 250 ml of Coke contains about 27g of carbs.
  • 250g of watermelon contains about 20g of carbs.
• Glycemic Load:
  • coke – (63 x 27)/100 = 17
  • watermelon – (72 x 20)/100 = 14

• low GL – 10 or less
• medium GL – 11-19
• high GL – 20 or more

Given this information:

• Despite watermelon having a higher GI, the actual impact on blood glucose (glycemic load) might be lower due to its lower carbohydrate content compared to Coke when similar serving is compared.

1. Nutrient Density:
   • Nutrient density refers to the amount of vitamins, minerals, and other beneficial nutrients per calorie of food. Watermelon, despite its higher GI, has some b vitamins, some minerals, antioxidants, and hydration due to its high water content. Coke, on the other hand, only has sugar.
2. Overall Macronutrient Balance:
   • Evaluating the balance of carbohydrates, proteins, and fats in a meal is crucial. A high-GI food can have a different impact on blood sugar when consumed with protein, fat, or fiber, which can slow down the absorption of glucose and moderate blood sugar spikes. Meaning, say if you combine 2 whole eggs with both, which is a source of protein and fat, the release of glucose in the blood might be slower. In other words, the impact of high-GI foods can be mitigated by consuming them as part of a balanced meal that includes fiber, protein, and healthy fats, which can lower the overall glycemic response.
3. Portion Size:
   • The quantity of food consumed significantly affects its impact on blood sugar. Even high-GI foods can be consumed in moderation as part of a balanced diet.
4. Individual Variation:
   • People’s responses to carbohydrates can vary widely based on factors such as age, activity level, health status, and individual insulin sensitivity.

Practical Considerations for a Healthy Diet

So, instead of worrying about high glycemic index foods, focus on eating sufficient calories (around maintenance), eat sufficient protein (1.2-2 g/kg of bodyweight), staying active and hydrated, exercising regularly, eating mostly whole foods (this will have some fiber along).

Conclusion

While the Glycemic Index can provide useful information about how foods affect blood sugar, it should not be the sole factor in determining the healthiness of a food. Evaluating foods based on their nutrient density, Glycemic Load, macronutrient composition, and portion size offers a more comprehensive approach to healthy eating.

High-GI foods can be included in a balanced diet when consumed in appropriate portions and as part of a meal that includes other macronutrients to balance their effects on blood sugar.

Research References

1. Jenkins, D. J., Wolever, T. M., Taylor, R. H., et al. (1981). Glycemic index of foods: a physiological basis for carbohydrate exchange. American Journal of Clinical Nutrition, 34(3), 362-366.
   • This foundational study introduced the concept of the glycemic index.
2. Augustin, L. S., Franceschi, S., Jenkins, D. J., et al. (2002). Glycemic index in chronic disease: a review. European Journal of Clinical Nutrition, 56(11), 1049-1071.
   • This review discusses the role of GI in the context of chronic diseases.
3. Barclay, A. W., Petocz, P., McMillan-Price, J., et al. (2008). Glycemic index, glycemic load, and chronic disease risk—a meta-analysis of observational studies. American Journal of Clinical Nutrition, 87(3), 627-637.
   • A meta-analysis examining the relationship between GI, GL, and chronic disease risk.
4. Venn, B. J., & Green, T. J. (2007). Glycemic index and glycemic load: measurement issues and their effect on diet–disease relationships. European Journal of Clinical Nutrition, 61(S1), S122-S131.
   • This paper highlights the challenges and considerations in using GI and GL to assess diet-disease relationships.