We’re finally abandoning BMI for better ways to assess body fat

Yet BMI remains so pervasive that it has embedded itself in healthcare policy, impacting who gets treated and who doesn’t. “The BMI system has been so ingrained in our culture that people start to believe that it’s the only way to determine health,” says Sarah Gilman at the University of California, San Francisco. “But it’s a very limited tool.”

A new approach

Many experts say it’s time to move on. Some have begun to frame the conversation around “metabolically healthy obesity” – a term for people who are overweight or obese yet have normal blood pressure, cholesterol and blood sugar levels. These individuals have a lower risk of heart disease than those who are metabolically unhealthy but have a “normal” BMI. They are evidence that BMI is not the be-all and end-all of health.

Meanwhile, more nuanced measures are being developed. Researchers are exploring ways to incorporate waist circumference, muscle mass, body fat percentage and more into a holistic view of health. Rubino, for instance, is working on a new metric that takes into account fat distribution and muscle mass, creating a more accurate picture of a person’s health. “This is a big opportunity in the field of predictive medicine,” he says.

As we step away from BMI, it’s clear that the relationship between weight and health is far more complex than we once believed. “The idea of a healthy weight is a fraught one,” says Gilman. “It’s not about a number but about how you feel in your body, what your body can do and how you engage with the world.”

I left that doctor’s office feeling ashamed and confused, but also determined. I would no longer let a single number dictate how I felt about myself. I would listen to my body, honour its strength and resilience, and reject the idea that health is a one-size-fits-all concept. BMI may have tried to tell me I was unhealthy, but I knew better. And I was ready to rewrite the rules.

Having hips and curves on your body is a beautiful and natural part of being a woman. However, society’s obsession with body size and shape has led to the development of metrics like Body Mass Index (BMI) that can be misleading and harmful. BMI is a one-size-fits-all measurement that fails to take into account individual differences in body composition and health.

For example, some individuals may have higher muscle mass, which can skew their BMI readings and categorize them as overweight or obese when they are actually healthy and fit. On the other hand, individuals with low body fat levels, such as female athletes, may appear “normal” according to their BMI but still face health risks like irregular menstruation and bone weakness.

Diana Thomas, a mathematician at the United States Military Academy, emphasizes the limitations of BMI, stating, “I have hips, I have curves on my body. And so to just put a cylinder on me and say, ‘We’re going to use this body measurement from your outside to tell us what’s on the inside,’ seems pretty limited.”

In response to these shortcomings, researchers and medical professionals are advocating for a more nuanced approach to assessing weight and health. The Lancet global commission on obesity has recommended a shift away from using BMI as the sole determinant of obesity. Instead, they propose distinguishing between pre-clinical obesity, where fat levels are a risk factor, and clinical obesity, where it is considered a standalone illness.

Furthermore, the commission highlights the importance of considering factors beyond BMI, such as the distribution of fat in the body. Visceral fat, which accumulates around internal organs, is a better predictor of health risks like heart disease, diabetes, and dementia. Tools like bioimpedance scales, which directly measure body composition, can provide more accurate assessments of excess body fat.

Alternative criteria, such as waist circumference, waist-to-hip ratio, and waist-to-height ratio, are also recommended for evaluating visceral fat and overall health. These measures take into account individual differences in body shape, age, gender, and ethnicity, providing a more personalized assessment of weight-related health risks.

Ultimately, the goal is to move away from a one-size-fits-all approach to weight and health. By considering the unique characteristics of each individual, healthcare providers can offer more tailored and effective interventions to promote overall well-being. Embracing diversity in body size and shape, including hips and curves, is essential for promoting body positivity and empowering individuals to prioritize their health and happiness.

Anand’s passion led her to delve into the disparities in health assessments based on BMI across different ethnic groups. She found that BMI was not an accurate measure of health for South Asian, Chinese, and Black populations, who showed higher rates of diabetes at lower BMIs compared to white people. The reasons for this discrepancy varied, with genetic factors playing a significant role in South Asian populations.

South Asian individuals, in particular, have lower muscle mass and higher fat mass compared to white individuals at the same BMI. This difference in body composition leads to a faster accumulation of fat around the abdomen, especially in the liver, which increases the risk of metabolic diseases. These findings prompted South Asian countries to challenge the conventional use of BMI in assessing health risks.

By 2022, several Asia-Pacific nations, including India, Singapore, Sri Lanka, and the Philippines, adopted their own BMI thresholds with lower cut-off points for obesity. These countries also began incorporating additional measures like waist circumference to provide a more comprehensive assessment of health risks. This shift away from solely relying on BMI highlights the importance of considering individual body composition and genetic factors in health assessments.

Anand’s research, along with other studies conducted over the past two decades, has shed light on the limitations of BMI as a universal health indicator. The push to move beyond BMI and explore more nuanced metrics like waist-to-hip ratio, waist-to-weight index, and body roundness index reflects a growing awareness of the need for personalized health assessments. As our understanding of how body shape and fat distribution impact health evolves, so too must our methods for evaluating and managing health risks. After facing rejection for her early grant applications to study BMI variations across different ethnic groups, one researcher refused to give up. Despite initial setbacks, her perseverance paid off as her groundbreaking work revealed significant differences in cardiometabolic risk thresholds based on ethnicity.

The researcher’s findings, as published in a study, showed that South Asian and Chinese individuals experience higher cardiometabolic risk at lower BMI thresholds compared to white Europeans. Surprisingly, the traditional BMI measure was found to be ineffective in predicting risk among Black and Inuit populations.

Nearly two decades later, the impact of this research is evident in the 2020 update of clinical practice guidelines in Canada. This update now includes lower BMI cut-offs for South Asian individuals and recommends the consideration of non-BMI measures in assessing obesity across all ethnic groups.

Following suit, other countries have begun to adapt their guidelines as well. In 2022, the National Institute for Health and Care Excellence in England and Wales issued new guidance promoting the use of waist-to-height ratio in routine care. This shift away from relying solely on BMI has been supported by various organizations, including the World Obesity Federation and the World Health Organization.

Critics of the traditional BMI measure, such as Rubino, emphasize the importance of using multiple health indicators in conjunction with BMI. This sentiment was echoed by the American Medical Association in 2023, which declared BMI as “imperfect” and recommended its use alongside other health measures.

The significance of moving away from BMI as the sole indicator of obesity is underscored by the current distribution of weight-loss medications such as Mounjaro and Wegovy. In countries like England, Japan, and the US, access to these medications is restricted based on BMI thresholds, which may not accurately reflect individual health needs.

With approximately 1 billion people worldwide classified as obese based on BMI, there is a growing recognition of the limitations of this measure. Embracing the complexity of individual biology, ethnicity, and lived experiences is crucial in redefining how we approach health and obesity-related diseases.

Ultimately, the shift towards using shape and distribution-based measures is not about disregarding the risks associated with obesity. Instead, it is about acknowledging the diverse nature of human bodies and moving towards a more personalized approach to healthcare. Health is not a one-size-fits-all concept, and it is essential to recognize and celebrate the uniqueness of each individual. Over the past few years, there has been a growing interest in sustainable living and eco-friendly practices. From reducing plastic waste to using renewable energy sources, people all around the world are making conscious efforts to protect the environment. One aspect of sustainable living that is often overlooked is sustainable fashion.

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