Approximately one in three Australian adults, or 32%, currently has a body mass index (BMI) of 30 or above, with an additional 34% falling within the BMI range of 25 to 29.9. In light of this, Australia’s health regulator has approved the use of Wegovy, a weight-loss variant of Ozempic (semaglutide), and Mounjaro (tirzepatide) for weight management as part of a comprehensive strategy that includes a reduced-calorie diet and physical activity. However, to qualify for these medications, adults must have a BMI of 30 or above, or a BMI of 27 accompanied by weight-related health conditions such as high blood pressure or sleep apnoea. Notably, these medications are not subsidized under the Pharmaceutical Benefits Scheme (PBS) for weight loss, which means users face significant out-of-pocket expenses.
These medications function by activating the GLP-1 receptor, leading to increased insulin secretion and enhanced glucose utilization by the liver. Consequently, users experience reduced appetite and a feeling of fullness after consuming less food. Clinical trials indicate that these treatments can lead to weight reductions of up to 20%, positively affecting health outcomes and overall quality of life. Despite this, reliance on BMI for determining eligibility remains prevalent, even as healthcare professionals advocate for more nuanced assessments of health.
BMI: A Limited Measure of Health
The concept of BMI was introduced by a Belgian mathematician in the 1830s to create a quantifiable measure of the “average man.” It was later adopted in the 1970s by an American physiologist and dietitian as a screening tool for obesity. Although BMI serves as a useful population-level measure, it does not capture the entirety of an individual’s health status. For example, individuals with considerable muscle mass may show a high BMI while maintaining low health risks. Conversely, older adults with lower muscle mass may face significant weight-related health challenges that BMI fails to highlight.
Weight alone does not provide a complete picture of an individual’s risk for health issues. Increasing physical activity and adopting a more nutritious diet can lead to health improvements, even if weight remains unchanged. This is particularly relevant for individuals with sedentary lifestyles, as enhanced physical activity can significantly benefit cardiovascular, respiratory, and mental health.
Redefining Obesity and Treatment Eligibility
Traditionally, obesity has been diagnosed when a person’s BMI exceeds 30. However, earlier in 2023, an international committee proposed a shift in the criteria for diagnosing obesity. This recommendation suggests that individuals with excessive body fat impacting their health should be classified as obese, including those with a BMI over 40. The new approach advocates for the consideration of waist circumference and direct body fat measurements obtained through specialized scales, with different thresholds for obesity based on age, gender, and ethnicity.
Moreover, the committee introduced the concept of “clinical obesity,” defined by organ dysfunction or significant functional impairment due to obesity. This comprehensive diagnostic framework emphasizes overall health rather than relying solely on BMI, aiming to provide a more accurate assessment of obesity and its associated health risks.
The committee also recommended that weight-loss treatments, including medications, should be tailored to individual needs and supported by evidence-based practices.
Incorporating alternative assessment tools is crucial. The Edmonton Obesity Staging System exemplifies a more holistic approach, combining BMI data with an assessment of existing health conditions, daily functioning, and psychological well-being. This system categorizes obesity into stages, allowing for a deeper understanding of health risks. Individuals at higher stages may experience serious health complications, while those at moderate stages may face conditions like high blood pressure and limited daily activity.
Utilizing this comprehensive assessment framework could significantly impact the prescription of weight-loss medications, ensuring that those with more severe health conditions, regardless of their BMI, have access to treatments that align with their health needs.
Complementing Medications with Lifestyle Changes
While medications can offer substantial benefits for many individuals, they are not universally effective, nor do they guarantee lasting weight loss, particularly without accompanying lifestyle modifications. Research trials involving these medications emphasize the importance of nutritional support, physical activity, and psychological guidance throughout the treatment process.
Regardless of whether individuals opt for weight-loss medications, those with weight-related health issues can enhance their physical function and overall quality of life through coordinated support from healthcare professionals, including dietitians, exercise physiologists, psychologists, and general practitioners.
In conclusion, revisiting the criteria for weight-loss drug eligibility to include a broader spectrum of health indicators could lead to more effective treatment plans. By moving beyond BMI as the sole determinant, healthcare providers can better address the complexities of obesity and improve health outcomes for a diverse range of patients.
