Published Sep 29, 2026 | 1:45 PM ⚊ Updated Sep 29, 2026 | 1:45 PM
Abdominal fat is not accounted for in BMI calculations. (Commons)
Synopsis: New research suggests BMI may miss an important heart-risk signal: abdominal fat. With nearly half of Indian men and more than half of women affected by abdominal obesity, five experts explain why normal weight does not always mean low cardiovascular risk, how belly fat affects the heart, and why waist measurement matters.
For decades, the weighing scale and BMI have been among the simplest ways of deciding whether someone is overweight. But for many Indians, the number on the scale may not tell the whole story.
A person can have a BMI within the normal range and still carry considerable fat around the abdomen, a pattern doctors say can accompany insulin resistance, high blood pressure, abnormal cholesterol and fatty liver, all of which can contribute to cardiovascular risk.
The scale of the problem is significant. A 2026 study using nationally representative NFHS-5 data from 707 districts found abdominal obesity in 56.6 percent of Indian women and 48.9 percent of men. Separately, the ICMR-INDIAB study estimated abdominal obesity in 36 percent of Indian adults using Indian waist thresholds of 90 cm for men and 80 cm for women.
Now, new research presented at the American Heart Association’s EPI|Lifestyle Scientific Sessions 2026 has added another piece to the puzzle. The study found that measures of waist size were more strongly associated with heart failure risk than BMI, while inflammation appeared to explain part of the association.
For doctors, the findings reinforce an idea that has increasingly shaped the understanding of obesity and cardiovascular risk: it is not only how much fat a person carries, but where it is stored.
“BMI only tells us about total weight, it says nothing about where that weight sits on the body,” said Dr Vikram Patil, consultant interventional and structural cardiologist at Narayana Health speaking to South First.
Someone can have a normal BMI and still carry excess fat around the belly, he said. When that happens, he pays closer attention to blood pressure, blood sugar and cholesterol rather than assuming that a normal BMI means everything is fine.
“This is especially true for Indians, who can develop heart risk at a lower body weight than people in many other countries,” Patil said.
Dr PRLN Prasad, consultant interventional cardiologist at Gleneagles BGS Hospital, Bengaluru, similarly said a normal BMI combined with a large waist can indicate excess fat around the abdomen and internal organs.
“That patient is usually treated as higher risk regardless of what the scale or BMI chart says,” Prasad said to South First, adding that doctors would typically look more closely at blood sugar and lipid levels.
This does not mean that BMI has become useless.
Rather, endocrinologists say it is a starting point. BMI is calculated from height and weight, but does not distinguish between muscle and fat or show where fat is stored.
“Two people can have the same BMI but have very different metabolic health,” said Dr Somashekar Reddy, consultant endocrinologist at Fortis Hospital, Bengaluru to South First.
“I would see BMI as a starting point rather than the only measure we should use when assessing obesity and metabolic risk.”
Abdominal fat is not simply stored energy sitting around the waist.
“Abdominal fat, particularly visceral fat, is metabolically active,” said Dr Sanjay K Shah, senior consultant in general medicine at Narayana Hospital to South First.
Unlike fat stored under the skin, visceral fat can release inflammatory substances and fatty acids that affect organs including the liver and pancreas. Over time, Shah said, this can contribute to insulin resistance, abnormal cholesterol, high blood pressure and diabetes.
Patil described belly fat as “biologically active tissue” that releases substances into the bloodstream that promote inflammation, affect blood sugar regulation and disturb cholesterol levels.
Over years, this low-grade metabolic and inflammatory stress can affect blood vessels and put additional strain on the heart, increasing the risk of heart attacks and heart failure, he said.
The important point, doctors say, is that these problems often cluster.
A larger waist may be accompanied by insulin resistance or diabetes, high blood pressure, elevated triglycerides, low HDL cholesterol and fatty liver.
“When we see several such findings together, it tells us that the patient may need earlier lifestyle intervention and closer monitoring rather than waiting for a major health problem to develop,” said Dr Rajpal Singh RL, director of cardiology at Fortis Hospital, Bengaluru, told South First.
This is where the issue becomes particularly relevant to India.
South Asians tend to carry a greater proportion of abdominal and visceral fat relative to overall body weight, doctors said. That means metabolic problems can emerge at BMI levels that might not conventionally be classified as obesity.
“South Asians, including Indians, tend to store more fat around the abdomen and internally compared with some other populations,” Reddy said.
Genetic and lifestyle factors can also contribute to insulin resistance, he said, meaning an Indian person does not necessarily have to be visibly overweight to develop diabetes, high cholesterol or fatty liver.
Shah similarly said South Asians tend to develop more abdominal and visceral fat relative to their overall body weight, with differences in body composition, genetics, diet and physical inactivity contributing to the pattern.
“As a result, metabolic problems can appear even when someone’s BMI does not fall into the conventional obesity range,” he said.
That is why a person who looks relatively slim can still have an unfavourable metabolic profile.
“We often see such cases,” Prasad said. “These patients look lean but carry significant visceral fat around the abdomen.”
He said the pattern, sometimes referred to as “normal-weight obesity”, can be easy to miss if assessment is based mainly on weight or BMI.
The latest research adds a cardiovascular dimension to the debate around abdominal fat.
Presented at the American Heart Association’s EPI|Lifestyle Scientific Sessions 2026, the study found that waist circumference and waist-to-height ratio were associated with heart failure risk, while BMI did not show the same relationship. The research also found that inflammation accounted for part of the association between measures of fat around the waist and heart failure risk.
The finding is significant because BMI has traditionally been one of the easiest ways to classify excess weight, but it cannot distinguish between different patterns of fat distribution.
The researchers’ findings therefore raise the possibility that measures of abdominal fat could provide additional information when assessing cardiovascular risk.
But there is an important caveat.
The study was conducted among African American adults, so its findings cannot simply be transferred to the Indian population.
“We should be careful about directly applying these findings to Indians because different populations can have different body composition and metabolic risk patterns,” Reddy said.
At the same time, he said the broader message is relevant because abdominal fat and insulin resistance are already recognised concerns in Indians.
“We need more Indian-specific research to understand the right cut-offs and how strongly these measurements predict future disease in our population.”
Patil also cautioned that the AHA research was presented as early conference research and had not yet been fully reviewed and published.
He said it should therefore be seen as reinforcing an existing line of research rather than as a final answer.
“In practice, I use waist size as one useful piece of the puzzle, never on its own, and always alongside blood pressure, blood sugar, and cholesterol,” he said.
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Doctors interviewed for this story broadly agreed that waist circumference deserves more attention during routine health assessments.
“It costs nothing and takes a few seconds with a measuring tape, yet it’s often skipped,” Patil said.
He stressed that measuring the waist should not replace blood pressure, blood sugar or cholesterol testing, but could add another early signal of metabolic risk.
Prasad also supported incorporating waist measurement alongside conventional cardiovascular risk checks.
He described it as a simple, inexpensive measurement that can provide information BMI may miss, particularly in a country where abdominal obesity is common.
Singh said waist circumference could be particularly useful during preventive health assessments because it takes little time and can identify people who may need lifestyle changes or closer monitoring before established cardiovascular disease develops.
Reddy said BMI remains more commonly used because it is quick and easy, but waist measurement can add information, particularly when doctors are assessing diabetes, insulin resistance or metabolic syndrome.
“If I had to choose one simple measurement, I would say waist circumference because it is easy to measure and easy to follow over time,” he said.
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The growing emphasis on waist size does not mean that everyone with a larger waist is destined to develop heart disease.
Nor does it mean that waist circumference can replace a comprehensive cardiovascular assessment.
Singh said two people with the same BMI should not automatically be assumed to have identical risk simply because their weight is similar. Doctors also need to consider blood pressure, glucose and lipid levels, family history, physical activity, diet, smoking, age and existing medical conditions.
Shah made a similar point, saying waist circumference should not be considered in isolation. Blood pressure, blood sugar, cholesterol, physical activity and family history all contribute to a person’s overall metabolic risk.
Reddy said an increasing waist becomes particularly concerning when accompanied by rising blood sugar, high triglycerides, elevated blood pressure or fatty liver.
“We should not wait until the person becomes clearly overweight before taking action,” he said.
For Indians, the commonly used waist thresholds are also lower than those used in many Western populations. The studies cite 90 cm for men and 80 cm for women, reflecting the higher metabolic risk associated with abdominal fat at lower levels in South Asian populations.
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Perhaps the biggest problem is not the measuring tape or the BMI calculation. It is the assumption that appearance tells us everything about health.
“Many people think cardiovascular screening is mainly necessary for someone who is visibly overweight or already has symptoms,” Singh said.
But cardiovascular risk develops over years and may not produce warning signs early, he said. Someone who feels healthy and has a normal weight still needs to pay attention to blood pressure, blood sugar, cholesterol, physical activity, diet and family history.
Patil put it more simply: looking slim or having a normal BMI does not automatically mean low heart risk, particularly among Indians.
“Heart health depends on many things together,” he said, including blood pressure, blood sugar, cholesterol, activity, diet, smoking, sleep and family history. “Body weight is just one piece of that picture.”
The weighing scale, then, is still useful. But it may not be telling the whole story.
For someone whose weight has barely changed but whose waistline has steadily increased, that difference may be worth paying attention to.
On World Heart Day, the message from doctors is not to abandon BMI, but to stop treating it as the entire picture. Sometimes, the number around your waist can tell you something the number on the scale cannot.
