Although BMI has traditionally been used to measure excess weight, and is used in the current definitions of obesity, the Commission highlighted one of its major weaknesses – BMI does not reflect body fat distribution.

As BMI does not differentiate between fat mass & lean mass, some people can have a normal or borderline overweight BMI score, despite living with excess body fat. In some cases, particularly in the elderly population, this could lead to a missed diagnosis of obesity and cause their health risk to go unnoticed.

The same problem can also be seen at the opposite end of the scale – some people living with high muscle mass but healthy levels of body fat, such as athletes, tend to have a higher BMI score. In some cases, this can lead them to be incorrectly classified as living with obesity.

This goes to show that although BMI is a valuable screening tool, indication of excess body fat, using tools such as Waist-to-Height Ratio, Waist Circumference and Waist-to-Hip Ratio can contribute to a better identification and diagnosis of obesity. To find out your Waist-to-Height Ratio, use our calculator provided below.

The Commission’s proposal of obesity as a condition characterised by excess body fat is only half of the story.

That’s because this definition does not consider how some people living with excess body fat have wider health complications such as cardiovascular disease or type 2 diabetes whereas others do not. This led the Commission to propose two new categories of obesity: preclinical and clinical obesity.

They define preclinical obesity as a condition of excess body fat associated with variable level of health risk, but no ongoing organ dysfunction and/or reduced ability to conduct daily activities.

They define clinical obesity as a chronic disease due to obesity alone and characterised by signs and symptoms of ongoing organ dysfunction and/or reduced ability to conduct daily activities.

Signs of reduced organ function can look like breathlessness caused by the effect of obesity on the heart or lungs. Reduced tissue function can include symptoms such as knee or hip pain caused by stiff joints and a reduced range of motion.

Daily activities that are difficult to complete can include self-care activities such as personal hygiene, bathing, toileting, dressing, and skin or foot care.

So, what new overarching definition of obesity did the Commission come to? In lay terms… ’A condition in which a person lives with excess body fat, and/or an unhealthy distribution of fat, caused by many factors that are not yet fully understood.’¹

Differentiating between high risk of illness or active illness with obesity is important as it can influence whether an individual’s weight-management goal is prevention- or treatment-focused.

This strategy is seen with other common conditions such as prediabetes, which usually can be managed with lifestyle changes, and diabetes, which requires medical treatment.

Since people living with clinical obesity already display signs of reduced organ function, the main purpose of clinical obesity care is to improve these health complications.

On the other hand, because preclinical obesity can increase the risk of factors obesity-related disease such as cardiovascular disease, type 2 diabetes and clinical obesity itself, the main purpose of preclinical obesity management is risk reduction.

It’s important to remember to speak to your doctor about both preclinical and clinical obesity.

This is because early interventions are key to helping prevent the symptoms of preclinical obesity progressing into clinical obesity. In both cases, the main purpose of obesity care is to improve your overall health, rather than a sole focus on weight reduction.

Overall, the work from this Commission supports the fact that obesity is a serious chronic disease, where earlier detection and more personalised diagnoses can help drive more tailored obesity care.

It is not yet clear what these recommendations will look like in practice. For example, delaying treatment until complications arise or excluding conditions like type 2 diabetes from diagnostic criteria contradict current guidelines and may impact access to care. Additionally, healthcare professionals will need further training and enough resources to support proper diagnosis, personalised treatment plans and follow up for people with obesity, without undermining the resilience of healthcare systems.

Regardless of how excess weight is classified, seeking support from friends, family and doctors early on can help you to take steps to protect your health for a healthier and happier future.