What the number actually measures
Glycaemic index ranks carbohydrate foods by how quickly and how far they raise blood glucose, compared against a reference food, when a fixed amount of available carbohydrate is eaten alone.
Read that definition again, because three assumptions are buried in it, and all three are usually false at an Indian dining table. It assumes a fixed carbohydrate quantity rather than a real portion. It assumes the food is eaten alone rather than in a meal. And it comes from testing in groups of people, where individual responses varied considerably.
That does not make it useless. It makes it a starting point rather than a verdict.
Broadly, values under about 55 are called low, 56 to 69 medium, and 70 and above high.
Where common Indian foods sit, approximately
These are indicative bands rather than precise values. Published figures for the same food vary with variety, growing conditions, processing and cooking method, and Indian data specifically is patchier than people assume.
Generally low
- Most pulses and legumes — rajma, chana, all the dals, lobia
- Whole and sprouted grams
- Barley
- Most non-starchy vegetables
- Milk and curd
- Apple, pear, guava, orange, berries
- Peanuts and most nuts
Generally low to medium
- Whole-wheat chapati made from coarse atta
- Several millets — ragi, bajra, jowar — though results vary with how finely they are milled
- Steel-cut and rolled oats
- Basmati rice, which is typically lower than most other white rice
- Sweet potato
- Banana, depending on ripeness
Generally medium to high
- White rice, particularly short-grain and well-polished varieties
- Idli and dosa made from a highly fermented refined batter
- Poha and upma made from refined preparations
- White bread, maida-based breads and biscuits
- Potato, especially boiled and mashed
- Most Indian sweets
- Sugary drinks and fruit juices
Why glycaemic load is the more useful number
Glycaemic index describes a food's quality. It says nothing about how much you ate — and quantity usually dominates.
Glycaemic load combines the two: it accounts for both the index and the actual carbohydrate in the portion. Watermelon is the standard example. Its index is high, but a normal serving contains little carbohydrate because most of it is water, so the load is modest.
The practical implication is unglamorous and important. A smaller portion of a higher-index food often produces a smaller glucose response than a large portion of a lower-index one. Two katoris of brown rice can affect you more than one katori of white rice. Anyone managing glucose who has replaced the grain but not reduced the quantity has usually achieved less than they expected.
Four things that change the response more than the number
What you eat it with
The single largest practical lever. Protein, fat and fibre eaten alongside carbohydrate slow gastric emptying and blunt the glucose rise.
This is why the traditional Indian thali is better constructed than the modern plate that replaced it. Rice with dal, sabzi and curd behaves quite differently from the same rice with a thin curry. Chapati with paneer or an egg behaves differently from chapati with pickle. If you change one thing after reading this article, change the composition of the plate rather than the grain on it.
How it was cooked
Cooking time, water content and processing all matter. Overcooked rice and mashed potato raise glucose faster than the same food cooked less and left intact. Finely milled flour raises it faster than coarse. A whole grain raises it more slowly than that grain ground to powder — which is why ragi as a whole grain and ragi as a fine flour behave differently despite being the same food.
Whether it was cooled after cooking
Cooking and then cooling starchy foods increases resistant starch, which is not digested in the same way. Rice cooked and refrigerated overnight, or the traditional practice of fermented leftover rice, behaves differently from rice served straight from the pot. Reheating retains some of the effect.
Ripeness, and the individual
A firm banana and a spotted one are not the same food. And individual glucose responses to identical meals vary substantially between people — enough that two people can follow the same evidence-based advice and get quite different results, which is worth knowing before you conclude you have failed.
Who should actually use this
Genuinely useful for: people with diabetes or prediabetes; women with PCOS, where insulin sensitivity is central, as discussed in PCOD vs PCOS; anyone with reactive energy crashes after meals; and endurance athletes timing fuel.
Less useful for: people without glucose issues who are simply trying to eat well. For them, the ordinary advice — more whole grains, more pulses, more vegetables, fewer refined and sweetened foods, sensible portions — delivers essentially the same outcome without arithmetic.
A caution: if you have diabetes, this is supporting information alongside medical care, not a substitute for it. Diet changes can affect medication requirements, and adjusting medication is a doctor's decision. Practical Indian guidance is in diabetes-friendly Indian foods.
What to actually do
Five changes that capture most of the value without turning meals into a spreadsheet:
- Build every meal around protein and fibre, and let the grain be the accompaniment rather than the centre.
- Fix the portion before the food. Halving the rice usually achieves more than swapping it.
- Choose coarser over finer — thicker atta, whole millets over fine flour, intact grains over powdered.
- Do not drink your carbohydrate. Juices and sweetened drinks are the fastest route to a glucose spike and the easiest thing to remove.
- Walk after eating. Ten to fifteen minutes after a main meal measurably reduces the post-meal rise, and requires no dietary change at all.
The glycaemic index is a useful lens. It is not a scoring system for food, and treating it as one produces people who eat badly with excellent numbers.
Two Indian examples worth working through
The brown rice disappointment. Somebody with prediabetes switches from white rice to brown, changes nothing else, and finds their readings barely move. This is the commonest frustration in Indian glucose management and it is entirely predictable. The switch improves fibre and micronutrients, both worth having, but the index difference between white and brown rice is smaller than people expect — and if the portion stayed the same, or grew because brown rice felt permitted, the load may not have fallen at all. What moves the reading is halving the rice and adding dal, vegetables and curd alongside it.
The millet assumption. Millets have deservedly good standing, and ragi, bajra and jowar are genuinely valuable grains. But a ragi flour so finely milled that it behaves like refined flour, made into a thin porridge with sugar and eaten alone, is not the food the reputation was earned by. The grain matters; so does the form, the accompaniment and the quantity. Whole or coarsely ground, in a mixed meal, is where the benefit lives. There is more on this in millets and their nutritional value.
Both examples make the same point from different directions. The number attaches to a food; the response belongs to a meal. Anyone advising on glucose who works from lists rather than from plates will keep producing this disappointment, and will keep blaming the client for it.