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world obesity day 2025: redefining obesity to shift the conversation beyond bmi and provide better care

while bmi-based measures are part of the obesity staging system in canada and obesity guidelines around the globe, there’s a move away from thinking just about weight and height to focus on health.

while bmi-based measures are part of the obesity staging system in canada and obesity guidelines around the globe, there’s a move away from thinking just about weight and height to focus on health.
obesity does not only put people at higher risk for high blood pressure, diabetes, osteoarthritis, and heart disease and stroke—many people also live with the psychological impact.  getty images
as science has revealed a more comprehensive understanding of obesity and influenced the diagnosis over the years, the international commission on clinical obesity has proposed new definitions of the disease in a recent report in the journal lancet diabetes & endocrinology.
the report, released in january, includes 18 diagnostic criteria for clinical obesity in adults and 13 criteria for children and adolescents for clinicians to better diagnose and develop personalized treatment plans.
as well, the report’s authors define two categories for diagnosis—clinical obesity and preclinical obesity. the first is a chronic disease linked to signs or symptoms of reduced organ function, like heart failure or sleep apnea, because of obesity alone. this also includes people who have challenges with daily activities like bathing, dressing and continence directly due to excess body fat. the latter category is for patients who present risk factors for obesity but have no evidence of reduced organ or tissue function and have no trouble with basic tasks.

reducing stigma for people with obesity to access proper care

the aim is for medical practitioners to understand and treat obesity as a disease, rather than a lack of willpower. big picture, the criteria will help to reduce the stigma for people with larger bodies and help them access proper care.
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“this is more of like a reframing of obesity and giving it a new definition, new terminology, on preclinical and clinical obesity, to treat obesity beyond just bmi (body mass index),” says dr. sandy van, an obesity physician in toronto and medical advisor to patient advocacy group obesity matters.
“one of the advantages is that they actually recognize obesity as a disease with varying levels of severity, so preclinical obesity identifies individuals at risk before and before organ damage occurs, while clinical obesity focuses on those already experiencing health complications. and this approach helps healthcare providers personalize treatment priorities.”
traditionally, diagnosing obesity is based on size using bmi which is a ratio of weight to height. the problem is, bmi doesn’t detect the difference between fat and lean mass, so people who may be fit and healthy can be misclassified as overweight. (think about athletes like heavyweight boxers who have large muscle mass and incredible stamina.)

body mass index oversimplifies obesity

bmi, as van says, is not a reliable measure and it oversimplifies the complexities of obesity. “when you want to get into the nitty gritty details, it’s something that we can use, but it’s one tool of many other things.” the basis of the assessment should determine whether excess fat is causing health problems, so blood tests identify high cholesterol, blood pressure readings indicate high blood pressure, images can show osteoarthritis, or  sleep studies detect obstructive sleep apnea.
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obesity canada
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another emerging fact is fat cells are complex. adipose tissue, otherwise known as body fat, operates differently when it’s around the internal organs, under the skin or inside the abdominal cavity, as research reveals. these fat cells contribute in different ways to the metabolic complications of obesity like insulin resistance, high blood pressure and appetite dysregulation.
and while bmi-based measures are part of the obesity staging system in canada and obesity guidelines around the globe, there’s a move away from thinking just about weight and height to focus on health.
obesity, like many diseases, is complicated and unique to each person.
“people are starting to understand that doctors are capable of treating obesity rather than going to a commercialized weight loss program or some sort of diet program,” says van, who is also a gp psychotherapist. her approach to patients is a blend of pharmacological and psychological techniques like cognitive behavioural therapy. “a lot of patients of mine already have a better understanding that there is something that is causing their weight that has nothing to do with willpower.”

world obesity day pushes for health system change

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obesity matters
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advocates say the important shift that needs to happen is changing systems to promote healthier lives, which is the message of world obesity day on march 4, 2025, so people living in larger bodies can feel accepted and understood by healthcare providers and policymakers. underlying the shift is breaking down the stigma that people in larger bodies have caused their health problems themselves.
and while lifestyle interventions are great for everyone’s overall health, weight loss for people with obesity may require medications, surgery and therapy to work through body image dissatisfaction and shame, van explains. the extra weight is not only putting people at higher risk for high blood pressure, diabetes, osteoarthritis, and heart disease and stroke—many people also live with the psychological impact.
“a key symptom of psychological impairment, which is internalized weight bias, is that people feel like there’s something wrong with them because they have higher weight. they feel like they’ve done this to themselves.” the self-blame and sense of shame of living in a larger body are reasons why many people haven’t gone to see a healthcare provider. they’re up against the stigma of obesity in society that often plays out in healthcare settings where they’re simply told to lose weight.
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“body image dissatisfaction, anxiety disorder, mood disorder, those are all things that might not be causative of obesity, but they definitely are associated. when somebody with pre-existing depression has obesity, their obesity and their depression can get worse. so there’s this bidirectional relationship that you cannot ignore.”

obesity commission report has holes, experts say

van points out that the lancet report has prompted controversy, with canadian physicians like herself concerned about the limitations of the framework that doesn’t address the psychological symptoms of obesity and overweight, and would require “research-grade” scanning to identify excess body fat that obesity clinics wouldn’t necessarily have access to. there is also the concern shared by the european association for the study of obesity, and the obesity medicine association, that people in the “preclinical obesity” category could be denied needed care. a diagnosis of pre-clinical obesity could mean a wait-and see strategy that could delay early interventions and worsen long-term health outcomes. this is in stark contrast to osteoporosis and diabetes where early diagnosis and prevention are standard care.
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further, canada is a leader in obesity medicine with a staging system that includes psychological impairment and treatment pathways for intervention, van adds.
another concern she has with the lancet model is how it might be interpreted by insurance providers where preclinical obesity recognizes people at risk, but coverage is denied until a patient progresses to clinical obesity.
“if we really want to improve obesity care, we need policy changes and insurance coverage that actually align with evidence-based treatment guidelines and not just new definitions. we risk reinforcing barriers rather than breaking them.”
obesity matters and its french division parlons obésité conducted a nationwide online survey of the organization’s registrants to better understand public sentiment surrounding the lancet report and challenges with access to care. while about 30 per cent were familiar with the report, most participants were familiar with bmi. nearly 90 per cent noted that bmi alone is not an adequate indicator of overall health, as one person shared, “bmi has never reflected my health. my fitness levels and blood markers tell a different story.”
respondents were also divided on the commission’s new framework, with some saying it might improve access to care and better-targeted treatments, and others uncertain whether healthcare and insurance systems would adapt accordingly. as one participant questioned, “will insurers recognize these new criteria, or will new barriers emerge?”
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the issue of weight stigma in healthcare was also highlighted by respondents who reported experiencing weight bias when seeking medical care. one question asked whether moving beyond bmi could reduce stigma. more than half of respondents agreed, and 63 per cent say that bmi contributes to negative biases in healthcare, including this revealing comment: “perhaps a new system will help individuals be seen as whole people rather than just numbers on a scale.”
karen hawthorne
karen hawthorne

karen hawthorne worked for six years as a digital editor for the national post, contributing articles on health, business, culture and travel for affiliated newspapers across canada. she now writes from her home office in toronto and takes breaks to bounce with her son on the backyard trampoline and walk bingo, her bull terrier.

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