BMI has been the benchmark in evaluating health and fitness for many years. The formula is quite simple: weight in kilograms divided by the square of height in meters. This would easily tell if one is underweight, within the healthy weight range, overweight, or obese. But with new research findings, scientists are now questioning its accuracy and usefulness as a total measure of body composition.

The report, published in The Lancet Diabetes & Endocrinology, has sparked a global conversation on rethinking BMI. Supported by more than 50 international medical experts, the report suggests classifying obesity into "clinical" and "pre-clinical" types for better diagnosis and treatment. The shift underscores a growing consensus: BMI alone may not tell the full story of your health.

While BMI is simple to calculate and universally accessible, it is far from perfect. It does not consider muscle mass, bone density, or fat distribution, leading to misleading conclusions in some cases. For example, athletes with a high muscle mass may be considered overweight, whereas individuals with normal BMI might carry unhealthy amounts of visceral fat.

A landmark study in JAMA Network Open studied more than 155,000 postmenopausal women and found that women with a normal BMI but a waist size over 35 inches were more likely to die from heart disease or cancer compared with their counterparts whose waists are smaller. That makes a great case for how BMI can be insufficient and fat distribution must be factored into account.

Not all body fat is equal. Subcutaneous fat, which lies just beneath the skin, is relatively harmless. The real health danger lies in visceral fat—fat that surrounds internal organs. Unlike subcutaneous fat, visceral fat is metabolically active, releasing stress hormones like cortisol and inflammatory substances that raise blood pressure, blood sugar, and cholesterol levels. These effects significantly increase the risk of conditions such as heart disease, type 2 diabetes, and certain cancers.

BMI Isn't Always the Best Measure of Body Composition — Here's What to Use Instead

Since BMI is not the most reliable measure, scientists and doctors have sought other means to measure body composition more accurately.

1. Waist Circumference

A simple tape measure can provide valuable insight into your health. Measure your waist at the level of your belly button, ensuring the tape is parallel to the ground. For women, a waist measurement under 35 inches is considered healthy, while for men, the goal is under 40 inches.

2. Waist-to-Hip Ratio

This is the ratio of your waist circumference to that of your hips. To calculate it, divide your waist measurement by your hip measurement. According to the National Center for Biotechnology Information, a ratio under 0.8 for women and 0.9 for men is considered healthy.

3. Body Roundness Index (BRI)

A newer method that seems to be receiving more attention involves the Body Roundness Index or BRI: height, weight, and girth are placed together to represent a more advanced view of what body composition says. Research presented in JAMA Network Open offers evidence that this BRI predicts mortality risk greater than BMI in some cases- a promising weapon for public health.

Also Read: Using BMI To Classify People As Obese Is Flawed Say Experts

Ways To Cut Off Unhealthy Fat

The good news is that visceral fat responds well to lifestyle changes. Here are three evidence-based strategies:

Time-Restricted Eating

Adopting an eating window of 12 hours—such as from 7 a.m. to 7 p.m.—can significantly reduce visceral fat, according to a study published in Nutrition Research Reviews. This approach not only helps control caloric intake but also reduces late-night snacking, a known risk factor for abdominal obesity.

Limit Alcohol Intake

Excessive alcohol consumption is associated with increased belly fat. A 2017 study published in Public Health Nutrition revealed that alcohol increases the levels of insulin and encourages the storage of fat in the abdominal area. Limiting alcohol to occasional indulgence helps avoid weight gain in this region.

High-Intensity Interval Training (HIIT)

HIIT involves repeated episodes of high-intensity exercise separated by periods of rest. A review in *Sports Medicine* concluded that HIIT is very effective in reducing visceral and total body fat. It can be noted that adding just 20 minutes of HIIT two times a week can make all the difference.

The reliance on BMI as a sole indicator of health is increasingly being challenged. While it remains a convenient screening tool, its limitations necessitate a broader approach that considers factors like fat distribution, waist circumference, and new metrics such as BRI.

In the simplest of words, health is multi-dimensional, and shifting perspectives from considering weight solely to broader measures of body composition will get people a much clearer understanding of where their health risks are so that they can take the action required for a better quality of life. Through adjustment to diet, exercise, or perhaps through innovative metrics like BRI, health is well within reach of the individual.

This dynamic conversation raises the point about personalized health screenings, which helps everyone get more relevant tools fitting their unique lives and circumstances. As body composition research is enhanced, so do the futures look brighter and brighter for the times of measurement when it comes to health.

Definition and diagnostic criteria of clinical obesity. The Lancet Diabetes & Endocrinology.

Association of Normal-Weight Central Obesity With All-Cause and Cause-Specific Mortality Among Postmenopausal Women. JAMA Netw Open. 2019

Waist-Hip Ratio. NIH.

Physiological responses to food intake throughout the day. Nutr Res Rev. 2014

Association between abdominal obesity and alcohol drinking pattern in normal-weight, middle-aged adults. Public Health Nutr. 2017

"Losing weight isn't about obsessing over diets or rushing to shed pounds."

It is about understanding the reasons behind why a person weighs as much as they do and adopting healthy habits to create long-term success. From an endocrinologist's viewpoint, managing weight involves a thorough approach. Factors such as hormonal imbalances, insulin resistance, thyroid conditions, polycystic ovary syndrome (PCOS), some medications, genetics, and lifestyle choices can all affect body weight. As a result, a single diet or exercise routine may not be equally effective for everyone.

Why Weight Management Needs A Personalised Approach

Also read: Delhi Air Pollution: Should You Move Your Morning Walk And Jog Indoors As AQI Nears 400?

Eating a balanced diet high in nutrients is a key principle to weight control. It's advised not to cut out all food groups or eat extreme low amounts of calories, but ensure that your diet includes moderate portions, lots of protein, fibre-dense, foods, veggies, fruits, and good fats. Participating in a regular exercise programme with cardio exercises and resistance training can boost your metabolic health.

Sleep and behaviour are equally vital. Poor sleep can impact hunger hormones and it can cause cravings, then add stress and emotional eating maintenance can be tricky. Keeping to a sleep routine, managing stress and setting realistic targets will aid in developing a lasting habit.

When Are Weight-Loss Medicines Or Surgery Considered?

Assessment of diet there are certain circumstances, when medical assessment would be the next step, such as significant unexplained weight gain, the failure to lose weight despite an effort, and if there is a presence of other manifestations/diseases like diabetes, high blood pressure, hormonal problems etc. A personalised evaluation is a review of medical history, medication, and relevant investigations and metabolic risk factors.

Your healthcare professional may recommend prescription weight-management medication to use beyond nutrition and lifestyle management, where your weight management plan is based on your BMI, related health conditions and clinical management. Your healthcare professional will need to monitor treatment with medication. You may also be considered for bariatric surgery where clinically indicated.

It's not about hitting the scales at a lesser weight; the aim should be to achieve good metabolic health, physical fitness and quality of life. The fact is that weight loss is a slow journey, and even small, sustainable weight loss can bring significant health gains. A custom program, ongoing assessment and adequate support will beat fad diets every time."

By Dr Hetashvi Gondaliya, Diabetes & Endocrinology, CK BIRLA HOSPITALS Jaipur

A 24-year-old marathon runner, Rachel Apa, collapsed and died two miles from the finish line at the New York City Marathon. In Hyderabad, 36-year-old IBM software engineer Kommineni Gopi died after suffering a heart attack shortly after completing a marathon.

Apa's death was attributed to rhabdomyolysis, a condition involving severe muscle breakdown, while Gopi died following a heart attack.

Also Read: Delhi AQI Crosses 2,000 Mark After Diwali: What Happens To Your Body Within Hours Of Exposure?

According to The New York Times, Apa was a former Division I field hockey player at Bucknell University who had trained for months. Gopi was an experienced amateur runner who had undertaken intensive training and multiple endurance runs.

Although such deaths are rare, the incidents highlight the physical demands of endurance running.

How Common Are Deaths During Marathons?

A study published in JAMA, involving 29.3 million US marathon and half-marathon finishers between 2010 and 2023, found:

• Cardiac arrest: 0.54 per 100,000 participants (1 in 185,000).
• Cardiac death: 0.20 per 100,000 (1 in 500,000).

Dr Sudhir Kumar, neurologist at Apollo Hospitals, Hyderabad, said survival has improved with better on-site CPR and defibrillation.

Also read: Water Or Electrolytes? Biggest Hydration Mistakes First-Time HYROX Athletes Make

Who Is At Greater Risk?

According to Dr Sudhir, risk factors include:

• Male sex: Cardiac arrest rates are approximately six times higher in men.
• Older age: Risk rises after 40–50 years.
• Underlying heart conditions: Including coronary artery disease, cardiomyopathy and myocarditis.
• Race distance: Full marathons carry higher cardiac arrest risk than half-marathons.
• Environmental stress: Heat, humidity, dehydration and illness.

Can Extreme Running Affect Heart Health?

Regular running is associated with lower cardiovascular and all-cause mortality and better blood pressure and glucose control.

However, prolonged extreme endurance training may increase the risk of atrial fibrillation, coronary artery calcification in some athletes and myocardial fibrosis in a small subset. These risks remain low for most runners.

What Causes Cardiac Arrest During A Marathon?

Read More: Lancet Study: 1 In 4 Adolescents Worldwide Report No Active Days Every Week: What Are The Health Risks?

Causes vary by age. Younger runners (below 35–40 years):

• Hypertrophic cardiomyopathy
• Arrhythmogenic cardiomyopathy
• Congenital coronary anomalies
• Myocarditis
• Inherited arrhythmias

Middle-aged and older runners:

Coronary artery disease is a major cause and can trigger heart attacks or dangerous heart rhythms.

Other causes include heat stroke, severe hyponatremia, aortic dissection, pulmonary embolism and complicated rhabdomyolysis.

What Is Rhabdomyolysis And Why Is It Dangerous?

Rhabdomyolysis occurs when damaged muscles release myoglobin and potassium into the bloodstream. Excess potassium can trigger dangerous heart rhythms, while myoglobin can damage the kidneys.

Warning signs include severe muscle pain, weakness and dark urine.

“A marathon is not ‘normal’ exercise. It is EXTREME exercise. While most people don’t develop a problem, deaths occur rarely too,” said Dr Rajeev Jayadevan, former president of IMA Cochin.

“Rhabdomyolysis (muscle breakdown) releases potassium into the bloodstream that causes cardiac arrest. Later events include BP crash and kidney shutdown,” he added on X.

Cardiac arrests often occur in the final quarter of a race, near the finish line or shortly after completion.

Why Is Marathon Training Important?

Attempting a marathon without adequate preparation can be dangerous.

“If you are not a trained runner, don't run. Running without understanding the science of it, running without being fit, running without having a baseline health check, running without proper stamina and endurance are all recipes to disaster,” warned Dr Deepak Krishnamurthy, director and lead cardiologist at KIMS Hospital, on X.

People over 40, those with diabetes or hypertension, smokers and individuals with a family history of premature heart disease should consider cardiovascular evaluation before intensive training.

How Can Runners Reduce The Risks?

During training:

• Increase mileage gradually.
• Avoid running during illness.
• Stay hydrated and include recovery days.
• Avoid excessive NSAID use.

• Acclimatise to the weather.
• Start at a manageable pace.
• Hydrate according to thirst.
• Stop for chest pain, fainting, unusual breathlessness or palpitations.

What To Do If A Runner Collapses

• Call emergency services.
• Start CPR if the runner is unresponsive and not breathing normally.
• Use an automated external defibrillator (AED) as soon as possible.

Early CPR and defibrillation can improve survival.

Marathons offer health benefits, but runners need adequate preparation and should recognise warning signs rather than push through them.

With Delhi's air quality nearing 400, doctors have advised people to reconsider their morning workout routines. Outdoor activities such as walking, jogging and cycling can increase exposure to harmful pollutants, particularly when air quality levels are poor.

While regular exercise is important for good health, exercising outdoors when pollution levels are high can affect respiratory and cardiovascular health.

Experts told HealthandMe that adjusting workout timings and choosing indoor alternatives can help reduce exposure.

Delhi's air quality deteriorated to the very poor category on Friday morning, with an Air Quality Index (AQI) reading of 391, just days before Diwali.

Forecasts indicate that the AQI could exceed 400 and enter the severe category between Friday and Sunday, with no immediate relief expected. Around 30 of the 59 monitoring stations across the national capital recorded severe pollution levels on Friday morning, with Rohini reporting an AQI of 475.

Should You Change Your Morning Workout Routine?

Dr Arunesh Kumar, Director and HOD, Pulmonology, Paras Health, Gurugram, told HealthandMe that when AQI levels are high, outdoor activities such as morning walks, jogging and cycling increase exposure to pollutants, particularly because breathing becomes faster during exercise.

Experts recommend moving workouts indoors when pollution levels are high. Yoga, stretching, weight training and low-intensity exercises can help you maintain your fitness routine.

"It's important to check the daily AQI before you go out and to consider moving your exercise indoors when the air quality is poor. You can maintain your exercise regime indoors with yoga, stretching, light strength training and the like. A well-ventilated indoor space is preferable and of course you should avoid doing your exercise near major traffic routes," Dr Arunesh said.

Also read: With Delhi AQI Nearing 400, Pollution & Flu Loom Ahead Of Diwali: What Happens When Both Hit Your Lungs?

What Indoor Exercises Can You Do When AQI Is High?

If air pollution levels are high, you can maintain your fitness routine by moving your workouts indoors. Some alternatives include:

• Yoga: Practise yoga indoors to stay active.
• Stretching: Include gentle stretching exercises in your daily routine.
• Weight training: Opt for indoor strength-training exercises.
• Low-intensity exercises: Choose light workouts that can be done indoors.

How Does PM2.5 Affect Your Health?

"Your breathing rate increases whilst working out, meaning that the pollutants you're breathing can get further into your lungs. This can lead to issues with your breathing and heart over time. Checking your AQI before going on a run/walk/cycle can help create a healthy lifestyle," Dr Rajesh Kumar Gupta, Director, Respiratory Medicine and Interventional Pulmonology, Yashoda Medicity, told HealthandMe.

People with asthma or heart conditions, children and older adults should be particularly careful about exposure on days with high pollution.

Read More: Air Pollution In Delhi: Experts Warn Of Red Eyes, Itching, Watering In Children

How Can You Maintain A Healthy Fitness Routine?

Poor air quality does not mean you need to stop exercising altogether. Experts recommend adapting your routine according to pollution levels.

• Check the AQI: Monitor daily air quality levels before planning outdoor activities.
• Move workouts indoors: Choose yoga, stretching, weight training or other indoor exercises when pollution levels are high.
• Avoid traffic-heavy areas: If you exercise outdoors, avoid major roads and congested areas.
• Stay hydrated: Drink enough water throughout the day.
• Eat a balanced diet: Include fruits, vegetables and whole grains in your meals.
• Prioritise sleep: Get sufficient rest.
• Avoid smoking: Smoking can further affect your health.

Lifestyle choices such as eating a balanced diet, staying hydrated, sleeping well and avoiding smoking support overall well-being, although they cannot prevent the harmful effects of air pollution.

The aim is not to stop exercising but to modify physical activity according to air quality conditions, said the experts. People with respiratory conditions, heart disease, older adults and children should be particularly mindful of their exposure on high-pollution days.