Body Mass Index (BMI) has long been the standard tool for determining whether a person falls into the underweight, healthy weight, overweight, or obese category. But while BMI remains useful for screening, doctors say it does not always provide the complete picture of a person's health. Increasingly, experts are paying closer attention to waist circumference and the waist-to-hip ratio (WHR), which can offer valuable insights into where body fat is stored. Research shows that abdominal fat, especially the fat surrounding internal organs, may be a stronger predictor of diabetes, heart disease, and other metabolic disorders than body weight alone.

What Is BMI?

BMI is calculated by dividing a person's weight by the square of their height. It is simple, inexpensive, and widely used to assess obesity at a population level. However, BMI has its limitations. According to Dr. Aparna Govil Bhaskar, Consultant Bariatric, Hernia and Laparoscopic Surgeon, Metaheal Clinic, Saifee, Apollo and Namaha Hospitals, Mumbai, BMI cannot differentiate between muscle and fat or indicate where fat is stored in the body. "For decades, Body Mass Index (BMI) has been the most widely used tool for classifying overweight and obesity. It is simple, inexpensive, and valuable for screening populations. However, BMI has important limitations when assessing an individual's health risk. Because it is based solely on weight in relation to height, it cannot distinguish between fat mass and muscle mass, nor does it provide information about the distribution of body fat," says Dr Bhaskar.

Why Waist-to-Hip Ratio Matters

The waist-to-hip ratio compares the circumference of your waist with that of your hips. It provides an indirect measure of abdominal or visceral fat the fat that surrounds vital organs such as the liver, pancreas, and intestines. "Increasingly, research has shown that where fat is stored may be as important as how much fat is present. This has led to greater emphasis on measures such as waist circumference and the waist-to-hip ratio (WHR), which provide an indirect assessment of abdominal fat accumulation," says Dr Bhaskar. Unlike the fat just beneath the skin, visceral fat is metabolically active and has been linked to chronic inflammation, insulin resistance, and hormonal disturbances.

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Health Risks Linked To Excess Belly Fat

Doctors warn that excess visceral fat significantly increases the risk of several chronic diseases. According to Dr Bhaskar, higher WHR is associated with increased visceral adiposity the metabolically active fat that surrounds organs such as the liver, pancreas, and intestines. Unlike subcutaneous fat, visceral fat contributes to chronic inflammation, insulin resistance, and hormonal disturbances, making it a major driver of cardiometabolic disease. High abdominal fat has been associated with:

  • Type 2 diabetes
  • High blood pressure
  • High cholesterol
  • Heart disease
  • Metabolic-associated fatty liver disease (MAFLD)
  • Polycystic ovary syndrome (PCOS)
  • Obstructive sleep apnoea
  • Several obesity-related cancers

Can You Have A Normal BMI But Still Be At Risk?

Doctors say some people may appear slim based on their BMI but still carry excessive fat around their internal organs. "Individuals with a normal BMI but an elevated waist circumference or WHR may still be at substantial metabolic risk a phenomenon often referred to as normal-weight obesity or TOFI (Thin Outside, Fat Inside)," adds Dr Bhaskar. On the other hand, athletes or individuals with higher muscle mass may have an elevated BMI but relatively low body fat and a healthier metabolic profile.

Why Doctors Don't Rely On BMI Alone

Experts now recommend assessing obesity using multiple measurements instead of relying solely on BMI. "Contemporary obesity assessment incorporates multiple parameters, including BMI, waist circumference, waist-to-hip ratio, body composition, and the presence of obesity-related complications," says Dr Bhaskar. This approach helps doctors better understand a person's overall health risk and personalise treatment accordingly.

Also read: What's India's Average BMI? How National Guidelines Differ From Global Norms

The Goal Is Better Health, Not Just Weight Loss

According to Dr. Bhaskar, obesity management is no longer focused only on reducing body weight. The goal of obesity management extends far beyond achieving weight loss. The primary objectives are to reduce excess visceral fat, improve metabolic health, prevent obesity-related complications, and enhance long-term quality of life. Early identification of people at high cardiometabolic risk allows timely intervention through lifestyle changes, medications, and, where appropriate, bariatric or metabolic surgery. BMI remains a useful screening tool, but it does not tell the whole story. Waist-to-hip ratio and waist circumference provide important information about abdominal fat, which is closely linked to diabetes, heart disease, and other metabolic disorders. Doctors say combining BMI with measures of body fat distribution offers a more accurate assessment of overall health and helps guide more personalised treatment strategies.



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