Thin outside, fat inside: belly fat and insulin resistance in Indians

Key takeaways

• At a similar BMI of about 22, one well-known comparison found 21.2% body fat in an Indian doctor and 9.1% in a Caucasian doctor.
• South Asians store more fat in the liver than white Europeans, even at lower average BMI.
• Indian guidelines treat a waist of 90 cm (men) or 80 cm (women), or a waist more than half your height, as a risk sign.
• Simple tests (HbA1c, lipids, liver function) reveal hidden risk.
• Strength training, protein, less refined carbohydrate and better sleep target the problem directly.

What does "thin-fat" actually mean?

"Doctor, I'm not even fat. How do I have fatty liver?" I hear some version of this every week. It is a fair question, and there is a clear answer.

The term "thin-fat Indian" was popularised by Prof. Chittaranjan Yajnik of KEM Hospital, Pune. It describes a body that may look normal or slim, with thin arms and legs, but carries a relatively high proportion of body fat, much of it around the abdomen and in organs, and relatively little muscle.

The best-known illustration, the "Y-Y paradox", appeared in The Lancet in 2004. Prof. Yajnik and Prof. John Yudkin compared their own bodies: similar BMIs of about 22.3, but body fat of 21.2% in the Indian and 9.1% in the Caucasian. An Endotext chapter on thin-fat obesity describes how the Pune Maternal Nutrition Study found that Indian newborns were already thinner in muscle but relatively fatter than European newborns. So this starts before we have even had our first vada pav.

Why does this happen in Indians?

Researchers point to several overlapping causes:

1. Early-life factors. Low birth weight and maternal nutrition, including vitamin B12 and folate status, are linked with unhealthy fat distribution and lower lean mass later in life.
2. Limited "safe" fat storage. The fat overflow idea suggests that when the fat under the skin is limited, extra fat spills into the liver, muscles and around the organs, where it causes more harm.
3. Low muscle mass. The thin-fat pattern comes with relatively low lean mass. Muscle is a major site where blood sugar is used, so less muscle means less capacity to clear sugar after meals.
4. Diet and lifestyle shifts. Cereal-heavy meals, refined flour, sugar in tea, fried snacks, long commutes and desk jobs. The Endotext chapter notes body fat rose quickly within a decade of rural-to-urban migration in India.

Where is the fat, and why does it matter?

A 2022 meta-analysis in Diabetologia, using UK Biobank and other data, found that South Asian men and women stored more liver fat than white Europeans despite slightly lower average BMI. The authors suggest this may help explain the higher diabetes risk in South Asians.

See, what happens is, fat inside the liver and abdomen is not just sitting there. It is metabolically active. It makes the liver and muscles resist insulin, raises triglycerides, lowers "good" HDL cholesterol and raises blood pressure. A 2013 review by Misra and Shrivastava links South Asians' greater truncal and intra-abdominal fat, and fat in the liver and muscles, to higher insulin resistance and abnormal lipids at lower BMI values.

How do you check whether this applies to you?

Measure your waist. Stand relaxed, breathe out, and measure around the middle at about navel level. Compare it with the Indian cut-offs, and divide by your height. NICE in the UK advises keeping your waist under half your height. For a person 170 cm tall, that is under 85 cm.

Ask for a few simple tests, particularly if you have a family history of diabetes or heart disease:

• HbA1c or fasting blood sugar;
• lipid profile (triglycerides and HDL in particular);
• liver function tests, and an ultrasound if your doctor suggests it;
• blood pressure.

A 35-year-old with a BMI of 23 and a 92 cm waist is often told his weight is "fine". The reports tell a different story. That is why Indian guidelines now combine BMI with waist and health effects, rather than relying on BMI alone. My article on why BMI cut-offs are lower for Indians explains the numbers.

The scale of the issue is national. The ICMR-INDIAB study estimated abdominal obesity in 39.5% of Indian adults, compared with generalised obesity in 28.6%. Many people have a risky waist without a high BMI. That is very important to understand.

So what actually helps?

The good news: the same habits that protect muscle and lower overall fat also shrink the waist, and the waist is often the first measure to change.

• Strength training two to three times a week. More muscle gives blood sugar somewhere to go. See why strength training matters.
• Protein at each meal, which helps fullness and muscle. Swap part of the rice or roti for dal, paneer, curd, chana, soya or eggs. My Indian vegetarian protein guide has portions.
• Fewer refined carbohydrates and sugars: sweet chai, biscuits, white bread, packaged snacks, juices.
• Daily walking, especially after meals.
• Sleep and stress management. Short sleep and shift work worsen insulin resistance.
• Limit alcohol, which adds to liver fat.
• Medical treatment where appropriate. The India Obesity Commission's 2025 definition places people with BMI above 23, excess abdominal fat and a related condition in Stage 2 obesity, where it recommends starting medicine early alongside lifestyle measures. Whether that suits you depends on your assessment. See who is eligible for medical weight loss.

How I approach this at Dr Tvacha

In The Endgame Weight Programme, I look at your waist, your reports and your family history together, not just your weight. Many people who "do not look overweight" have a good reason to address belly fat, and many others need only habit changes and periodic checks. The Rs 499 video eligibility consult, available across India, is where we make that distinction, and then the choice is yours.

Written by

Dr Amit KarkhanisAesthetic Physician · MBBS, Dip. Dermatology (UK) · Reg. No. 2001/02/1124

Founder of Dr Tvacha, practising in Thane since 2005. Leads the weight loss and hair programmes.