The glycemic index (GI) of foods

The glycemic index (GI) shows how much and how quickly a particular food raises blood glucose levels because of the carbohydrates it contains.

GI does not reflect calories; it reflects the effect of carbohydrates on blood sugar.

➤ How does the body absorb carbohydrates?

During digestion, carbohydrates are broken down into glucose, which is absorbed into the bloodstream.
This process involves:

• salivary enzymes
• gastrointestinal enzymes
• the intestinal wall

For glucose to enter cells, the body needs insulin — a hormone that moves glucose into the muscles, liver and other tissues.

Types of carbohydrates

Simple carbohydrates

• Monosaccharides: glucose, fructose, galactose
• Disaccharides: sucrose, maltose, lactose

Complex carbohydrates

• Polysaccharides: starch, fiber

Fiber (dietary fiber)

• is not broken down into glucose
• slows digestion and lowers GI

⚠️ A “complex” carbohydrate does not always mean a low GI.

➤ What is the role of insulin?

Insulin

• lowers blood glucose
• helps the body use energy
• when there is excess energy, helps store it

👉 Fat is stored not because of insulin, but because of a calorie surplus.
Insulin takes part in the process; it is not the culprit.

➤ How is the glycemic index measured?

GI is measured like this

• a person is given 50 g of carbohydrate in the form of pure glucose
• the change in blood sugar is measured over 2 hours
• this curve is taken as 100%
• other foods are rated against this standard

GI reflects

• how quickly
• and how high
  blood sugar rises

High vs low GI – what is the difference?

High GI

• blood sugar rises quickly and sharply
• large amounts of insulin are released
• hunger returns soon

Low GI

• blood sugar rises slowly and moderately
• energy stays stable
• you stay full for longer

What does GI depend on?

1. The amount of fiber
   the more fiber, the lower the GI
2. Heat and mechanical processing
   1. whole apple ≈ 25
   1. apple juice ≈ 45–50
   1. apple compote ≈ 70+
3. Adding protein and fat
   they slow digestion and lower the overall GI
4. The structure of the food
   the easier it is to chew and digest, the higher the GI

Example

100 g white bread (GI ≈ 95)
100 g rye bread (GI ≈ 50)

The calories and carbohydrates may be similar, but:

• white bread raises blood sugar more sharply
• triggers a larger insulin release
• does less to control appetite

GI, bulking and cutting

• When bulking
  simple carbohydrates are fine after training
• When burning fat
  low- and medium-GI foods are preferred

❗ Nothing is forbidden — what matters is quantity, timing and context

Insulin index (II)

Some foods

• do not raise blood sugar much
• but do raise insulin (e.g. some dairy products)

The insulin index shows exactly this and complements GI data.

✅ Conclusion

✔️ GI is an important indicator, but not the only one
✔️ The form of the food, combinations and quantity all matter
✔️ Low GI helps with appetite control
✔️ Fat gain depends on your overall energy balance

Author: Irakli Kenchoshvili / Tidanigym.ge

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