Cardiologists push back against BMI obsession, warning that being ‘thin on the outside’ may hide true health and longevity.

Focusing solely on body weight can create a limited view of what it truly means to age well and maintain long-term health. Integrative cardiologist Dr Sanjay Bhojraj, who has more than two decades of clinical experience, recently addressed this issue while discussing longevity in an Instagram post.

“Weight is easy to measure. It’s also incomplete,” he wrote.

According to Dr Bhojraj, the real goal for long-term health should be metabolic health, not just weight management. “If longevity is the goal, metabolic health is the real target. The scale tells you mass, but it does not reveal how your body is functioning, adapting, or ageing,” he explained.

This means that even people who fall within a so-called healthy weight range may still carry hidden health risks if other important health indicators are not balanced.

To gain a more accurate picture of long-term health, he recommends monitoring key markers such as resting heart rate, blood pressure, fasting glucose, and muscle mass. Tracking these indicators regularly can provide deeper insight into how efficiently the body functions and how well it may perform in the future. As he notes, these metrics reveal how effectively the body operates and how resilient it will be over time.

The aim, he adds, is not to dismiss weight entirely but to place it within a broader framework of health indicators that together influence longevity and overall quality of life.

Why BMI and body weight can be misleading

Dr CM Nagesh, medical director and senior consultant cardiologist at Cardea Super Speciality Hospital, explains that relying solely on weight or Body Mass Index (BMI) can be clinically misleading.

“BMI cannot differentiate between muscle mass, bone density, and body fat,” he says.

For example, someone with significant muscle mass may be labelled “overweight” according to BMI standards despite having excellent cardiovascular health. On the other hand, an individual with a normal BMI may still have normal-weight obesity, often referred to as “thin outside, fat inside” (TOFI).

In this condition, excess visceral fat accumulates around internal organs. This deep abdominal fat releases inflammatory substances that increase the risk of insulin resistance, heart disease, and premature death.

“The scale only measures gravitational pull, not metabolic health,” Dr Nagesh explains. “Longevity is determined by tissue quality and metabolic efficiency—factors that cannot be captured simply by body weight.”

How key health markers work together

Together, markers such as resting heart rate, blood pressure, fasting glucose, and muscle mass provide a clearer picture of how well the body’s cardiovascular and metabolic systems are functioning.

Dr Nagesh notes that resting heart rate and blood pressure offer insight into endothelial function—the health of blood vessel linings—and the autonomic nervous system. Lower values typically indicate a stronger heart and more flexible arteries.

Meanwhile, fasting glucose levels reflect how sensitive the body’s cells are to insulin. When muscle mass is also considered, the overall metabolic picture becomes clearer.

“Skeletal muscle is not just responsible for movement,” he explains. “It acts as an endocrine organ and serves as the body’s largest metabolic storage site.”

Greater muscle mass improves insulin sensitivity by storing blood sugar as glycogen, helping regulate blood glucose levels. Taken together, these markers reveal not only whether someone is free from disease but also whether their body has a strong metabolic reserve—the ability to process nutrients efficiently and handle physical stress.

Steps to monitor and improve these health markers

To keep track of these deeper health indicators, Dr Nagesh recommends starting with an annual metabolic panel through a healthcare provider to establish baseline measurements for fasting glucose, cholesterol levels, and blood pressure.

At home, resting heart rate can be monitored using a smartwatch or fitness tracker. Over time, a gradual decrease often reflects improving cardiovascular fitness.

To improve these markers, he advises incorporating resistance training at least twice a week, as building muscle increases the body’s capacity to store glucose and helps lower fasting blood sugar levels.

This should be combined with moderate-intensity cardiovascular exercise, which can improve vascular health and help reduce blood pressure.

Finally, maintaining good sleep habits is essential. Chronic sleep deprivation raises cortisol levels, which can contribute to increased blood pressure and insulin resistance regardless of diet.