Why Indians get sick at a lower weight

The observation that started it

In 2004 two physicians compared themselves. Both had a BMI of 22.3, which is squarely, boringly normal. The Indian had 21.2 per cent body fat. The Caucasian had 9.1 per cent. Same height-to-weight ratio, more than double the fat.

It became known as the YY paradox, and it has been reproduced many times since. Indians carry more fat, and carry it in worse places, at any given BMI. The phenotype has a name in the literature: thin-fat, or in the clinic, TOFI, thin on the outside, fat on the inside.

How it works, in four steps

1. The safe storage tank is small. Subcutaneous fat, the fat under the skin, is where the body prefers to put surplus energy. It is metabolically fairly harmless there. South Asians have a markedly reduced capacity to expand it. Adipose tissue studies show an overlap with partial lipodystrophy, the group of conditions where people cannot make normal fat tissue at all.
2. So it spills. When the subcutaneous tank is full, the surplus goes where it should not: around the intestines as visceral fat, and into the liver, pancreas, heart, kidney and skeletal muscle. This is why an Indian and a European with identical total body fat can have very different amounts of visceral fat.
3. Liver fat is the hinge. Fat inside the liver drives insulin resistance, pushes out the particular pattern of blood lipids Indians are known for, high triglycerides with low HDL and small dense LDL, and makes the liver release glucose it should be holding. Most of what looks like a sugar problem starts as a liver problem.
4. It is set before birth. The Pune Maternal Nutrition Study found Indian newborns are thin in skeletal muscle but relatively fat, compared with British newborns. A generation of maternal undernutrition followed by a rapid nutritional transition has produced adults primed for exactly this.

What follows from it

• Treatment thresholds are lower. That is why the Indian guideline starts calling weight a problem at BMI 23 rather than 25, and considers bariatric surgery from BMI 27.5 in the right circumstances, against 35 or 40 in Western guidance.
• Normal-weight obesity is real. Indians with a completely normal BMI but a high body fat percentage have been shown to carry roughly 2.7 times the odds of type 2 diabetes. You can be thin and still have this problem.
• You start with less muscle. This is the corollary that gets forgotten, and it matters enormously during weight loss. An Indian at a given BMI has less lean mass to begin with, so losing muscle during rapid weight loss costs more here than it does elsewhere. It is the reason a whole page of this section is about protein.

Sources: Thin Fat Obesity, the Tropical Phenotype of Obesity, Endotext. Yajnik CS, Pune Maternal Nutrition Study. Revised definition of obesity in Asian Indians, 2025.