Thin Outside,
Sugar Inside

Picture two slim, middle-aged doctors standing side by side. One British, one Indian. Same BMI: 22.3, right in the middle of the “healthy” range.

These were real people: Dr John Yudkin of London and Dr Chittaranjan Yajnik of Pune, two diabetes researchers. When their bodies were scanned, the British doctor’s weight was about 9% fat. The Indian doctor, who actually looked the thinner of the two, was about 21% fat, more than double. [1]

They wrote it up in The Lancet in 2004 as the “Y-Y paradox”, after their initials. [1] It became the classic picture of what researchers call the thin-fat Indian: less muscle, more fat, and much of it hidden inside the belly, where you can’t see it in a mirror. [3]

A study followed 1.5 million adults in England for a median of six and a half years. White adults with a BMI of 30 (officially obese) had a certain risk of developing type 2 diabetes. South Asians reached that same risk at a BMI of just 23.9. [2]

What does that mean in kilos? Take someone 5 feet 5 inches tall (1.65 m):

About 17 kg less body weight, the same risk. That is why Indian doctors set their own lines back in 2009: overweight from a BMI of 23, not 25. [4] In 2025 they went further, saying BMI alone misses too much and that waist size and belly fat must be checked too. [4]

In villages near Pune, Dr Yajnik’s team measured hundreds of newborns. The mothers were small: on average about 1.52 m tall with a BMI near 18. Their babies weighed about 2.7 kg, far lighter than British babies. [5]

But the Indian babies were not simply “small all over.” They had less muscle and smaller organs, yet had held on to their fat. [5] A baby short of food in the womb seems to protect its fuel store first. Later scientists add a caution: it’s fat kept, not extra fat. [3]

The pattern lasts. Pre-teen Indian children in another study had lower BMIs than white British children but a higher body-fat percentage, higher fasting sugar and more insulin resistance. [6] Then comes the modern Indian life of more rice, more scooters and less walking. A body built for scarcity meets a life of plenty.

The result is visible in the numbers. India has an estimated 101 million people with diabetes and 136 million more with prediabetes. [7] Karnataka is among the southern states where more than 1 in 10 adults has diabetes. [8]

Fat under the skin of the hips and thighs mostly sits quietly. Fat stored inside the abdomen, wrapped around the liver and gut, behaves differently. It is linked much more strongly to insulin resistance, where the body’s insulin stops working properly and sugar stays in the blood.

South Asians tend to store more of their fat in exactly this place, and their belly fat appears to be more inflammatory too. One sign: in Indian children, a marker of insulin resistance climbs more steeply as they gain fat than it does in European children. [3]

Here is the Indian picture in one comparison. Among adults in the national ICMR-INDIAB survey, about 28.6% had general obesity by BMI, but 39.5% had abdominal obesity. [7] In other words, millions of Indians whose BMI looks fine are carrying a risky belly.

That is why India’s 2025 obesity definition, written by Indian diabetes experts, puts the waist at the centre and no longer relies on BMI alone. [4]

In 2025 the ICMR-INDIAB team published the most detailed look yet at what Indians actually eat, based on the diets of more than 18,000 adults. Their headline: about 62% of the average Indian’s daily calories come from carbohydrates, among the highest anywhere. Protein is only about 12%. [9]

People with the highest carbohydrate intake had about a 30% higher risk of newly diagnosed type 2 diabetes than those with the lowest. [10] White rice dominates in the south and east; wheat in the north. Interestingly, Karnataka is one of only three states where millets are a main staple, alongside Gujarat and Maharashtra. [11]

Now the twist. Swapping white rice for milled whole wheat or millet flour did not lower the risk if the total amount of carbohydrate stayed high. [10] Grinding a grain into flour makes it digest faster, so atta and millet flour can raise blood sugar almost as quickly as white rice. [12]

What did help, in the researchers’ modelling: moving just 5% of daily calories from carbohydrates to protein from pulses, dairy, eggs or fish. [9] On a plate, that looks like a little less rice or ragi and a little more dal, curd or egg.

After a meal, glucose floods into the blood. Working muscles pull sugar out of the blood to use as fuel, so movement helps clear it. [13] The muscle is your biggest sugar sponge, and Indians tend to start with a smaller sponge: less muscle for the same body weight. [3]

A 2022 review in Sports Medicine pooled seven studies comparing sitting, standing and light walking. Short walks of just 2 to 5 minutes, repeated through the day, lowered blood sugar by about 17% compared with sitting still. Standing helped too, but less. [13] The best window is soon after eating, within 60 to 90 minutes, when the sugar peak arrives. [14]

So the old habit of a short stroll after lunch, or a shatapavali after dinner, turns out to have real chemistry behind it. Regular exercise that builds muscle makes the sponge bigger still.

Chennai’s Madras Diabetes Research Foundation built the Indian Diabetes Risk Score (IDRS) for exactly this. It needs no lab, just your age, your waist, how active you are and your parents’ history. Health workers across India use it in community screening. [15] Measure your waist at the navel, standing relaxed, after breathing out. Add up your points:

Notice what’s missing: your weight. A slim 52-year-old office worker with a 92 cm waist and one diabetic parent scores 30 + 10 + 30 + 10 = 80. That is high risk, without a single kilo of “overweight” on the scale. (Illustrative arithmetic.)

The last myth is the quietest one: “I’ll get checked when I feel something.”

Type 2 diabetes usually gives no warning for years. That is why the Union Health Ministry’s national NCD programme aims to screen every adult aged 30 and above for diabetes and blood pressure, free, at government health facilities including the Ayushman Arogya Mandirs. [16] [17] The cut-off is age, not waistline.

And the reason to check early is hopeful, not scary. Prediabetes is the stage before diabetes, and India has an estimated 136 million people in it. [7] ICMR’s chief has said prediabetes is reversible with diet and activity. [18] Finding it early is how you get to use that window.

Go back to the two doctors from Episode 1. Same height-and-weight number, completely different insides. India’s diabetes story is the same: a country that looks thinner than the West on paper, carrying its risk where the scale can’t see it. The tools to see it are cheap: a tape measure, a short walk, a little more dal, and one blood test after 30.