Diabetes Distilled: Beyond BMI – a practical framework for assessing and staging obesity

It is now widely recognised that BMI does not capture the complex impact of obesity on a person’s health, and recent guidelines from NICE and the Lancet Commission on Diagnosis of Obesity encourage use of additional measures to identify excess adiposity that correlate more closely with significant dysfunction (NICE, 2025; The Lancet Diabetes Endocrinology, 2025).

The NICE NG246 guideline recommends use of waist circumference and waist:height ratio as additional measurements to identify excess adiposity. Staging tools can help us understand and document the impact of obesity, and three of these in common use are summarised in Box 1.

The Edmonton Obesity Staging System (EOSS) includes three domains and helps stratify obesity into four stages (Sharma and Kushner, 2009). An online calculator allows speedy use in consultations.

The alphabetically organised, multiple-domain, four-stage King’s Obesity Staging System (KOSS) incorporates psychosocial and economic impacts of obesity (Aasheim et al, 2011).

The Lancet Commission Obesity Criteria (LCOC) uses 18 specific criteria relating to 11 systems to differentiate between preclinical and clinical obesity, recommending behavioural and lifestyle interventions for those with preclinical obesity and consideration of pharmacological and surgical options for those with clinical obesity (Rubino et al, 2025). However, this binary division is perceived by many as both too simplistic and too complex, with difficulty classifying some people in whom there is no obvious clinically significant dysfunction, such as diabetes or heart disease.

In a bid to overcome some of these challenges, four UK obesity experts have sought to provide a practical tool which would aid clinicians in making a holistic diagnosis of the impact of obesity, and hence therapy decisions, and which would also allow tracking of progress alongside the use of anthropometric measurements, which often underestimate or overestimate real-life benefits of obesity therapies.

An integrated framework

Ko and colleagues sought to integrate the LCOC and KOSS into a single framework to allow more comprehensive, practical and easier staging of obesity. This is designed to ensure consistent communication and agreement between clinicians and to allow tracking of progress across the 15 domains. The authors propose that stages 0 and 1 of the integrated framework can be mapped to preclinical obesity, as defined by the Lancet Commission, while stages 2 and 3 map to clinical obesity.

The domains, and how they track to stages in the integrated framework and the LCOC clinical and preclinical obesity categories, are shown in Table 1. The integration of these two staging tools may offer the following benefits.

For clinicians, a practical, comprehensive and individualised approach to staging the impact of obesity:

• Accurate diagnosis.
• Tracking of treatment progress across physiological and psychological domains.
• Ability to measure success by clinical outcomes, as recommended by the Lancet Commission.

For people living with obesity, a reduced focus on weight loss alone as the only important and documented outcome:

• It is hoped this will translate to less stigma.
• A more compassionate, person-centred approach.
• Staging and management which consider their quality of life.
• Recognition, assessment and tracking of their psychosocial burdens.

Limitations

The authors cite a number of challenges and limitations of their integrated framework:

• Some domains of the KOSS are subjective, similar to some parameters in the LCOC used to differentiate between preclinical and clinical obesity.
• Despite this, interobserver variability has been shown to be low.
• Using patient-reported outcome measures (PROMs) could improve standardisation.
• Some conditions (e.g. stroke or myocardial infarction) will be irreversible, fixing people at stage 2, for example, even if improvements occur in other domains used for tracking progress.
• Inclusion of a collection of different conditions (e.g. skin conditions) with different potential impacts in the “Other” domain.
• The clinical mapping of the KOSS stages to the definitions of preclinical and clinical obesity has yet to be validated in real-world settings.
• More research will be needed to identify whether the integrated model works as effectively as the two separate models.

Conclusions

This integrated model seeks to build on the LCOC and KOSS models to shift the focus of obesity management from purely weight loss to tracking a more holistic view of how obesity is impacting individuals. It is hoped this integrated framework will help reduce stigma and provide a practical tool for improving quality of care, with benefits for both clinicians and people living with the disease of obesity.

Implications for practice

The last 2 years have seen huge changes in guidance on how we should diagnose and manage obesity, and most would now agree that obesity is a chronic disease requiring long-term management. BMI is not an effective measure of adiposity or likely health impact, so measuring waist:height or waist:hip ratio is becoming more mainstream.

However, with time pressures in consultations, it is unlikely that we are using staging systems consistently, if at all. In particular, it can be challenging to use the Lancet Commission criteria to decide whether the person sitting beside us has preclinical or clinical obesity if they don’t have a designated condition such as diabetes, and this can influence whether behavioural and lifestyle management alone should be recommended or whether this needs to be combined with the offer of pharmacological or surgical options.

In primary care, some of us use the EOSS to estimate functional impact, and the online calculator makes it easy to use in the consultation, much as we use the QRISK3® or Fibrosis-4 calculators. However, only three domains are included in the EOSS, so it fails to capture many important impacts of obesity.

In a recent BMJ opinion piece, Ellen Fallows, GP and Fellow of the British Society of Lifestyle Medicine, reminds clinicians about the significant stigma faced by people living with obesity, and suggests we consider reframing primary care consultations to focus on the whole person rather than the numbers on a scale (Fallows, 2026). She encourages clinicians to dig deeper, to explore the individual’s potentially modifiable drivers of ill health and what can realistically be achieved to change them; many of these will be contributing to obesity and ongoing symptoms, such as pain or low mood. This holistic approach resonates with the integrated framework discussed here.

As winter pressures and year-end QOF/QAIF targets recede, it is a great time to try out this new tool, especially in those cases where you are uncertain whether the person fits into the LCOC clinical obesity stage. I have printed out the staging and tried it out; it takes longer than the EOSS using the online calculator, but for those who do not have a definite comorbidity to diagnose clinical obesity, it offers clarity.

Delving deeper into the psychological and social impacts of obesity felt worthwhile, and I am sure it will encourage me to place more people in the clinical obesity stage in future. I am looking forward to using the framework to track progress in a more holistic way than simply relying on measurements alone. And in cases where we can see that the person sitting beside us has excess adiposity, we may consider offering the option to explore psychosocial factors rather than encouraging people to step on our scales.

If you haven’t read Dr Fallow’s opinion piece, I strongly recommend doing so. It is a short piece that provides useful resources for increasing access to healthy food, and it is thought-provoking. Spending a few minutes understanding the person’s life better, rather than rushing to measure weight, may be more acceptable, especially if the person is reluctant to step on the scales. I would also strongly recommend trying out the new integrated staging tool. I look forward to hearing whether it does offer the benefits we discuss here in the real world.