Doc Talk: Why a Normal BMI Doesn't Always Mean Good Metabolic Health

A normal BMI does not always indicate good metabolic health. Understanding visceral fat, waist measurements and lifestyle habits can help identify hidden health risks and improve long-term metabolic health.

Doc Talk: The hidden link between belly fat and lifestyle diseases.

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Key points generated by AI, verified by newsroom

• Normal BMI is misleading; visceral fat impacts metabolic health.
• Indian study shows metabolic obesity despite normal BMI.
• Waist-to-height ratio provides a better measure of risk.
• Lifestyle changes: strength, diet, activity, sleep improve health.

A normal reading on the weighing scale does not necessarily mean a healthy metabolism. For Indians, the distribution of body fat may be as important as total body weight. For years, weight management has been reduced to a deceptively simple equation: maintain a healthy body weight and the risk of lifestyle diseases will remain low. This assumption is increasingly difficult to defend. A person can fit comfortably into old clothes, have a body mass index (BMI) within the normal range, and still carry excess fat around the abdomen that warrants medical attention.

The problem is not with bulging or collecting fat in your belly, but abdominal fat is highly important only if it is visceral fat that is deep fat. Velcro means fat that is deep inside the stomach around the internal organs. Unlike the fat lying just under the skin, visceral fat is active in metabolism and leads to insulin resistance, elevated cholesterol, and inflammation that raises the chances of developing type 2 diabetes and cardiovascular disease.

For India, this deserves particular attention. The nationally representative ICMR-INDIAB-23 study, published in 2025, reported that 43.3% of the population had metabolic obesity despite a BMI below 25 kg/m². This finding challenges the assumption that a normal BMI is sufficient evidence of metabolic health. It also strengthens the case for looking beyond body weight when assessing an individual's risk.

Why A Normal BMI Can Be Misleading

BMI measures weight in relation to height. It does not distinguish between muscle and fat, identify where fat is stored or directly measure insulin sensitivity. Two people with identical BMIs can therefore have substantially different body compositions and metabolic risk profiles.

This distinction is particularly relevant to Indians, who may develop metabolic abnormalities at lower levels of BMI than some other populations. A sedentary lifestyle, limited muscle mass, prolonged sitting, and a diet high in refined carbohydrates and energy-dense foods can contribute to a pattern in which a person appears relatively lean but carries excess abdominal fat. 

Contemporary professional routines may worsen the situation. Working at a desk for too long, eating in-between meetings, having meals delivered frequently, spending late hours in front of screens, and poor sleeping behavior make it difficult to stay active and keep the weight. It is not that any of these habits lead to abdominal obesity. They can collectively contribute to body changes and changes in metabolic processes without changing weight significantly. Genetic traits, age, hormone-related issues, some medications, and existing health problems can also play a role in body fat distribution.

Not Every Belly Indicates A Metabolic Problem

It is necessary to differentiate visceral fat from subcutaneous fat found under the skin and can be held with the fingers. The body shape of an individual can sometimes give clues to posture, abdominal bloating, gastrointestinal problems, or more serious ailments. However, one's appearance cannot be enough to assess the amount of visceral fat present in the body or the presence of metabolic disease. A better way to start is the waist measurement. The waist-to-height ratio is a straightforward method of evaluating central obesity along with BMI, and it takes the waist measurement and height using the same measurement units for both.

For instance, the waist-to-height ratio of an individual standing at a height of 160 centimeters with a waist measurement of 84 centimeters is equal to 0.525. The resulting value is within the range of values implying excessive abdominal fat according to conventional medical sources.

In general, the ratio should ideally be less than 0.50. The ranges between the ratios of 0.50 and 0.59 indicate the presence of excessive abdominal fat, and a ratio greater than 0.60 requires more serious concern. Such limits do not serve as a conclusive diagnosis but as indicators that help to assess the level of risk associated with a person’s ratio.

The next step is to analyze what the ratio might mean clinically. In accordance with the person’s age, medical background, and other risk factors, the doctor could request certain tests to assess their blood pressure, blood glucose level, and fat content level. In some situations, a doctor could suggest conducting assessments that are suitable for the specific case of a patient. 

The Solution Is Not Simply To Eat Less

One of the least helpful responses to abdominal fat in a person with a normal BMI is to recommend indiscriminate weight loss. Restrictive dieting can reduce muscle mass, leave nutritional needs unmet, and make the person lighter without necessarily improving body composition.

The more appropriate objective is to reduce excess abdominal fat, preserve or build muscle and improve metabolic markers. That requires a shift from weight-centred thinking to health-centred behaviour.

Start with strength training two times in a week. Walking and other aerobic physical activities will help to improve the cardiovascular system; however, resistance exercises are also vital for the sustainment of muscle mass and insulin sensitivity. People who are 18 and older must do muscle strengthening exercises involving the largest muscle groups not less than twice a week and along with aerobic exercises. According to the World Health Organization, individuals need to engage in moderate aerobic activity between 150 and 300 minutes a week or a similar amount of vigorous activity. However, if you are not used to exercising, it would be wise to embark on your exercise plan little by little, as it is advisable to refrain from training too hard. 

Secondly, instead of cutting food groups out of your diet, consider changing your dishes. Indian cuisine can prove to be quite effective for maintaining an efficient metabolism if it includes a sufficient amount of protein, vegetables, lentils, whole grains, and balanced fats. Protein can be sourced from dals, beans, yogurts, eggs, fish, and even soy for vegetarians. Substituting refined grains, sweetened drinks, regular desserts, and junk food for more nutrient-dense counterparts will work much better than going on a low-carb diet. 

Third, breaks from longer periods of sitting should be taken. The effects of a single exercise session are not enough to make up for a non-physical day otherwise. Take breaks from sitting in between plans in the day, after a meeting, or make it a habit to walk after every meal, and take stairs instead of lifts. Doing this will keep your body in a state of motion. If you work in a sitting job, it might be practical to set a timer every half an hour or so to remind yourself to get up and move a bit.

Fourth, it is necessary to include sleep and stress in the program. If sleep is restricted for a long time or stress is present for a long period, then it can influence one’s appetite and therefore food choices and the way the body utilizes glucose. The right sleep pattern should be established and maintained for successful implementation of the health program.

When Should Medical Advice Be Sought?

An increasing waistline at a time of stable body weight, along with a family history of diabetes and hypertension, aberrant cholesterol levels, or a previous case of gestational diabetes, calls for an appointment with a physician. The more risk factors are present at the same time, the stronger the justification for such a visit.

People must not depend on the use of home scales or online calculators and cannot make an assumption about their metabolic condition based on the Internet claims about such concepts as cortisol abdomen or insulin resistance. These methods are of no help when it comes to measuring metabolic rates of any individual. The same applies to such concepts as supplements, detox drinks, fat-burning products, or abdominal exercises for the purpose of losing visceral fat. 

A Better Definition Of Healthy Weight

With the way metabolic obesity is gaining acceptance, we have to step away from the common form of preventive medicine. Simple screening won’t suffice anymore just by measuring your body weight, height, and calculating the BMI if there are warning signs, such as central obesity. Waist circumference, some lab tests, activity levels, and family medical history can be equally significant. For people, the current message is just as clear;  the task isn’t losing as much weight as possible, but rather building muscle and improving fitness levels. Even though a normal BMI can assist in the screening process, it cannot be considered an indicator of good health anymore.

[Disclaimer: The information provided in the article is intended for general informational purposes only. It is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified healthcare provider with any questions you may have regarding a medical condition.]