Body weight targets that stigmatise and potentially harm patients continue to be commonly used in everyday clinical practice, but are outdated and long overdue for change, obesity experts have argued.
Presenting at this year's International Congress on Obesity in Melbourne (October 18-22), experts, patient advocates and clinical ethicists have called for the outdated methods of determining body weight targets to be urgently amended, arguing that judgements based on weight metrics - such as BMIs (body mass index) or unrealistic weight goals - are detrimental to patients' health.
Instead, the experts are urging health professionals to focus on treating obesity by setting goals and recommendations that are centred on the individual, as often broad targets for an 'ideal' or 'normal' weight aren't in fact ideal or normal.
Dr Alex Craven, an obesity surgeon from Austin Health in Melbourne, and his colleagues have drawn on existing research to describe how concepts such as an 'ideal body weight' or a 'normal' BMI are overly simplistic, putting a patient into a specific category that hinges on a specific decimal place, but doesn't take into account their actual health.
"These constructs suggest there are distinct categories of underweight, ideal, overweight and obese, with sharp boundaries that hinge on a decimal place," Dr Craven said.
In reality, the link between body weight and health is more complex, he said, adding: "As a disease, obesity has many outcomes. Increased body weight is only one outcome, and it's not the most important."
Body weight is not the best predictor of ill health
Having a higher body weight increases the risk of developing diseases such as type 2 diabetes and high blood pressure, but it's not a simple relationship, the experts argued.
"You could be categorised as 'normal weight' by BMI but have health problems associated with excess fat, or you could be categorised as having 'obesity' and have no health problems," explained Dr Priya Sumithran, the Head of Obesity Medicine at Austin Health.
"The problem with using weight metrics alone to set treatment goals is that they put too much emphasis on a target weight and that can be misleading."
Evidence suggests the risk of developing metabolic diseases like type 2 diabetes, heart disease and stroke is much more complicated than simply having excess weight. For instance, where the fat is distributed and the way it interacts with the body are critically important.
At the same time, the pressure to achieve and maintain an unrealistic body weight can have substantial psychological and social impact on individuals, and prioritises weight-based outcomes over health. Declaring "a normal weight range" can fuel bias and stigma, demotivate patients and promote eating disorders such as binge eating, the experts added.
Patient-centred goal setting in obesity treatment
The goals and perceived success of obesity treatments such as surgery, medications and lifestyle interventions are often linked to targets that have been based on notions of an 'ideal' or 'normal' body weight.
It is important health professionals go beyond this outdated and inaccurate approach to ensure they are making patient-centred recommendations, the authors argued.
When it comes to treating obesity, the seminar highlighted that the amount of weight lost - and its impact on the patient's health outcomes - is significantly more important than their final weight.
"Outcomes like controlling obesity-related diseases, improving physical function and better mental health are not only important to patients," said Andrew Wilson, an advocate for people with a lived experience of obesity from the Weight Issues Network in Australia.
"They are also linked to medically important outcomes like life expectancy and quality of life. Focusing on these is good for everyone."
"Body mass index is a practical screening tool that can be used in assessing people with obesity," added Professor Louise Baur, President of the World Obesity Federation and Chair of Child and Adolescent Health at the University of Sydney.
"While it's simple and cheap for doctors and other health professionals to use, it must be used in conjunction with a good clinical assessment that looks at whether physical and psychological health complications are present."
