Millets Have a Lower Glycemic Index, But Portions and Cooking Methods Still Determine How Healthy They Are

A bowl of jowar roti and a bowl of white rice can produce nearly identical blood sugar spikes if the jowar portion is large enough and the roti is made without adequate fibre from vegetables alongside it. A 2021 meta-analysis published in Frontiers in Nutrition by Anitha et al., which reviewed 19 studies on millet consumption across South Asian populations, found that millets do lower postprandial blood glucose compared to refined grains, but only when consumed in controlled portions and as part of a mixed meal. Eaten in isolation, or in the quantities many Indian households use when they switch from rice, the glycemic advantage narrows significantly.

The glycemic index of pearl millet (bajra) sits between 54 and 68 depending on preparation. Finger millet (ragi) ranges from 68 to 79 in some preparations, higher than many people expect, and close to the range for parboiled rice. The number changes based on particle size, water absorption during cooking, and what the millet is eaten with. A ragi mudde eaten with a thin sambar delivers a different glycemic outcome than ragi flour stirred into sweetened milk.

Millets contain phytates, compounds that bind to minerals like iron, zinc, and calcium and reduce how much of them your body actually absorbs. ICRISAT research on pearl millet has documented phytate levels high enough to meaningfully reduce iron bioavailability, which matters in a country where iron-deficiency anaemia affects roughly 53% of women of reproductive age according to the National Family Health Survey-5 data. Eating millets as a health food while relying on them as a primary iron source can work against the goal if preparation steps that reduce phytates are skipped.

Soaking millets for 8 to 12 hours before cooking reduces phytate content by 20 to 30%. Fermentation, the process behind idli-style ragi preparations and traditional koozh in Tamil Nadu, reduces phytates further and also improves protein digestibility. Malting, used in commercial ragi powder products, is another effective method. These are not optional refinements. They are the difference between millets functioning as a nutritional grain and functioning as a fibre-heavy carbohydrate with blocked mineral uptake.

The shift from rice or wheat to millets in Indian households often happens as a straight substitution: the same quantity, the same plate, the same meal structure. That substitution does not automatically reduce carbohydrate load. Bajra flour and jowar flour carry roughly 67 to 70 grams of carbohydrates per 100 grams, comparable to whole wheat atta. The fibre content is higher in most millets, which slows digestion and produces a more gradual glucose curve, but fibre does not cancel carbohydrates.

Three bajra rotis eaten with ghee and no significant vegetable component deliver more calories than two wheat rotis with dal and a sabzi. The millet roti is not automatically the lighter option. Portions are the controlling variable, and the research supports this: the Frontiers in Nutrition meta-analysis noted that glycemic benefits in the studies it reviewed were most consistent when millet portions replaced, rather than added to, existing grain intake.

Whole grain millets behave differently from millet flour, and millet flour behaves differently depending on how finely it is milled. Coarsely ground bajra retains more of its bran and germ, which slows digestion. Commercially packaged ragi flour is often finely milled to improve texture, which increases the surface area available for rapid enzymatic breakdown, meaning faster glucose release.

Cooking method compounds this. Pressure cooking millets until very soft breaks down resistant starch, reducing the fibre advantage. Cooking them to a slightly firm texture, the way traditional ambali or thick porridge preparations work, preserves more resistant starch and produces a slower digestive response. Popping or roasting millets, as in puffed jowar snacks, raises the glycemic index substantially. A puffed jowar snack marketed as a healthy grain alternative can have a glycemic response close to that of a puffed rice product.

Adding fat, ghee, coconut oil, or cold-pressed groundnut oil, to millet preparations does slow gastric emptying and moderates the glycemic response, but it also adds caloric density. The trade-off is worth understanding rather than assuming the fat is neutral.

The practical implication: soak whole millets before cooking, cook to a firm rather than mushy texture, pair with legumes or vegetables that add protein and fibre, and keep portions to the same size you would use for any other grain. The grain is genuinely useful. The assumption that switching to it is sufficient is what causes the problem.