The Flaws of BMI and its Impact on Health
Queensland-based Sarah Cox recalls that in 2018, her doctor advised her to lose weight because her body mass index (BMI) was too high, despite her feeling healthy and experiencing no physical health issues. Now 35, Cox said the advice triggered an eating disorder that lasted two and a half years.
She said at the time, the doctor did not carry out blood tests or other health screenings but instead prescribed weight loss medication and referred her to an exercise physiologist and dietitian.
“Their plan, which was done purely to reduce my BMI, is what made me unhealthy, is what made me sick, and is what started two and a half years of hospitalizations and almost losing my life.”
The Limitations of BMI in Obesity Diagnosis
BMI is a diagnostic tool that has been used for the past 50 years to estimate a person’s body fat. The simple formula takes a person’s weight in kilograms and divides it by the square of their height in meters.
But experts say it’s far more complex. Professor Wendy Brown, chair of the Department of Surgery at Monash University, told SBS News it’s a good measure, but it’s very limited “because it doesn’t account for what the weight is made up of, and also where the weight is carried”.
A person with a BMI over 30 is considered to be ‘obese’, which is typically deemed unhealthy. “So if you are an athlete and you weigh a hundred kgs and you are solid muscle, your BMI might flick up to 30, but you’re obviously a really healthy person because you’re lean and you’re fit and you’re active,” she said.
“But if your BMI is 30 and that’s largely made up of fat, particularly if that fat’s carried around the central area or around your heart, then that becomes an unhealthy situation.”
“So the old measure where we just looked at your height and your weight and didn’t consider what was making up that weight and where it was carried. It’s not nuanced enough to help us know who we need to be helping to lose weight.”
Brown is a member of the global commission on clinical obesity, which is proposing a major overhaul of obesity diagnosis. The commission published a report in The Lancet Diabetes & Endocrinology journal on Wednesday, endorsed by 75 medical organizations globally, which says current approaches are too reliant on BMI.
“What [the commission] is proposing is that we continue to measure the BMI, but we supplement that with measurements that will help us understand where weight is being carried,” she said.
“There are also some other tests we can do — x-rays and also body composition measures — that will tell us exactly how much fat a person has, but those tests are a little more expensive and not necessarily accessible to everyone in the community.”
The Criticism of BMI as a Health Metric
Dr Fiona Willer, a lecturer in nutrition and dietetics at Queensland University of Technology, believes it’s time to ditch the BMI altogether. “It’s a terrible tool. [It’s] not fit for purpose,” she told SBS News.
“It was developed by a mathematician hundreds of years ago [as a way] to standardize human bodies. And of course, we know that people come in lots of different shapes and sizes, and it’s really hard to get a handle on how to compare one person with another using those measurements alone.”
Willer explains the so-called “cut-offs” — used to classify a person as underweight, normal weight, overweight, or obese — hold a number of different biases, including when it comes to ethnicity. The BMI was initially based on a study set of European men.
“Of course, not everyone is a thin white male, wasn’t then and isn’t now,” she said. “There has been an attempt to try to adjust for people’s different genetic and ethnic backgrounds. [For example] smaller framed populations have lower cutoff points.”
“The cutoff points themselves, I should add, though, are essentially pretty arbitrary. They tend to be round numbers for ease, but bodies aren’t made with round numbers in mind in terms of health risks. So there’re flaws in using the BMI overall.”
Willer said the BMI is problematic for people across the weight spectrum. “We’ve got this kind of cultural assumption that you look like what you eat and that if you eat a certain way, your body will end up looking a certain way.” Varsha Yajman said it took her three years to receive a diagnosis for an eating disorder, which started when she was 14, due to what she describes as a fixation on her BMI.
“My weight kept dropping, but the whole idea was, ‘Oh, just eat more and exercise less, and you’ll be fine’. There was no acknowledgement of the mental side of things,” the 22-year-old said. “And then when it came to my BMI, it was ‘Oh, well, it’s not severely low. That’s okay’. Or ‘You’re still within the range’.”
Conclusion
The limitations of BMI as a health metric have been brought to light by experts in the field of obesity diagnosis. The reliance on BMI alone to determine health status can lead to misdiagnosis and potentially harmful interventions. It is crucial to consider additional factors such as body composition and where weight is carried to provide a more accurate assessment of an individual’s health.
FAQs
What is BMI?
BMI, or body mass index, is a tool used to estimate a person’s body fat based on their weight and height. It has been criticized for its limitations in accurately assessing health status.
Why is BMI considered problematic?
BMI is considered problematic because it does not account for factors such as body composition and where weight is carried. This can lead to misclassification of individuals and potentially harmful interventions.
The Challenges of Diagnosing Eating Disorders
Many individuals struggle to receive a timely and accurate diagnosis of an eating disorder, leading to delays in receiving proper treatment and support. Varsha Yajman, for example, spent three years navigating the healthcare system before finally being diagnosed with an eating disorder. Her experience highlights the challenges that individuals face when trying to determine the severity of their condition and the level of help they require.
Delays in Diagnosis
Yajman’s fixation on her Body Mass Index (BMI) played a significant role in delaying her diagnosis. She questioned how bad her condition needed to be before she could receive the necessary help. This dilemma is all too common among individuals struggling with eating disorders, as they grapple with the severity of their symptoms and the reluctance to seek help.
New Categories for Obesity
The Australian government is proposing new categories for obesity to provide tailored health advice and evidence-based care to individuals struggling with weight-related issues. These proposed categories aim to address the varying degrees of obesity and ensure that individuals receive appropriate support based on their specific needs.
Pre-Clinical Obesity
One of the proposed categories is pre-clinical obesity, which describes a condition where a person has normal organ function and no ongoing illnesses despite being classified as obese based on their BMI. This category aims to acknowledge individuals who may have a larger body size but do not experience any negative health consequences as a result.
Clinical Obesity
On the other hand, clinical obesity is defined as a condition where obesity is linked to noticeable signs or symptoms of reduced organ function or a decline in the ability to perform daily activities. This category targets individuals who experience significant health implications due to their obesity.
Differing Perspectives
While some experts, like Willer, express concerns that these new categories may lead to further stigmatization and medicalization of weight-related issues, others, such as 56-year-old Lexii Marquardt, view the proposal as a positive step forward. Marquardt, who falls into the pre-clinical obesity category, emphasizes that her larger body size has not impacted her overall health and well-being, highlighting the complexity of how obesity is perceived and managed.
Professor Tim Gill, from The Obesity Collective, supports the new diagnostic criteria as a significant advancement in addressing obesity. He believes that these new categories will help allocate healthcare resources more effectively and target individuals who require immediate care.
Conclusion
The challenges of diagnosing eating disorders and managing obesity are multifaceted and require a nuanced approach that considers individual health needs and experiences. By implementing new categories for obesity and reevaluating diagnostic criteria, healthcare professionals can better support individuals struggling with weight-related issues and ensure that they receive the appropriate care and resources.
FAQs
How can individuals struggling with eating disorders seek help?
Individuals seeking support for eating disorders or body image concerns can contact the Butterfly National Helpline at 1800 ED HOPE (1800 33 4673) or visit www.butterfly.org.au for assistance.