Understanding Glycemic Index in Foods
What is Glycemic Index?
The Glycemic Index (GI) is a ranking system that measures how quickly carbohydrates in foods affect blood glucose levels. Foods are ranked on a scale from 0 to 100, with pure glucose having a value of 100.
The higher the GI number, the more rapidly that food raises blood sugar levels.
Low Glycemic Index Foods (GI ≤ 55)
Foods with a low GI are digested and absorbed more slowly, causing a gradual rise in blood sugar levels.
Common low GI foods include:
- Most fruits (except watermelon and dates)
- Apples (GI: 36)
- Oranges (GI: 43)
- Berries (GI: 25-40)
- Most vegetables
- Carrots (GI: 35)
- Broccoli (GI: 15)
- Sweet potatoes (GI: 44)
- Legumes
- Lentils (GI: 32)
- Chickpeas (GI: 28)
- Kidney beans (GI: 24)
- Whole grains
- Steel-cut oats (GI: 42)
- Quinoa (GI: 53)
- Barley (GI: 28)
High Glycemic Index Foods (GI ≥ 70)
Foods with a high GI are quickly digested and absorbed, causing rapid spikes in blood sugar levels.
Common high GI foods include:
- Refined grains
- White bread (GI: 75)
- White rice (GI: 73)
- Rice cakes (GI: 82)
- Processed foods
- Breakfast cereals (GI: 70-85)
- Potato chips (GI: 76)
- Pretzels (GI: 83)
- Starchy vegetables
- Baked potato (GI: 85)
- Watermelon (GI: 72)
- Parsnips (GI: 97)
Athletes often combine high and low GI foods strategically. High GI foods can be beneficial immediately after exercise for quick energy replenishment, while low GI foods are better for sustained energy before exercise.
Don't assume all natural foods have a low GI. Some fruits like watermelon and dates have high GI values, while some processed foods like pasta can have moderate GI values.
Medium Glycemic Index Foods (GI 56-69)
For completeness, it's worth noting that many foods fall into the medium GI category:
- Whole wheat bread (GI: 69)
- Basmati rice (GI: 58)
- Sweet corn (GI: 60)
- Bananas (GI: 58)
- Raisins (GI: 64)
The glycemic index of foods can be affected by various factors including ripeness (in fruits), cooking method, and food combinations.
A practical meal combination might look like:
- Pre-workout: Steel-cut oats (low GI) with berries (low GI) for sustained energy
- Post-workout: White bread (high GI) with honey (high GI) for rapid glycogen replenishment
