We can argue various criticisms of the paper, but the most important one is the danger of introducing the concept of pre-obesity.

Diagnosis and treatment should always be personalized, and it is essential to emphasize the importance of phenotyping and characterizing obesity from the perspective of chronic, biological obesity, based on excess adipose tissue. If we assume this differentiation between 'pre-obesity' and 'clinical obesity,' it implies that obesity should only be treated once it has clinical complications and that in the preclinical phase, it is always preventable or reversible. In many cases, due to the chronic nature of obesity, this would only delay efficient diagnosis and intervention to prevent the onset of complications.

It is crucial to clearly define how complications are assessed and what is considered the clinical manifestation that differentiates the proposed 'pre-obesity' from 'clinical obesity.' I offer two comparisons:

1. Type 2 Diabetes: For a long time, prediabetes (altered blood glucose without meeting diagnostic criteria by numerical value) was thought not to require treatment but only monitoring. However, evidence shows that complications of type 2 diabetes, such as diabetic retinopathy, can already be present in this phase.
2. Chronic Kidney Disease: Before it can be clinically diagnosed through lab tests, there are stages of the disease that cannot be detected in routine clinical practice but still constitute kidney disease. By the time it is diagnosed, it is often in a more advanced stage, and valuable time for treatment has been lost.

The same applies to these definitions of pre-obesity and obesity. Low-grade inflammation and adipose tissue dysfunction are already present when there is an excess of body fat, and this means obesity—not a preliminary phase. There is already a societal trend, both among the general population and healthcare professionals, to minimize and underdiagnose obesity, even when it is clinically complicated.

This concept of pre-obesity does not provide any benefit in terms of making us more proactive in raising awareness among society, patients, and professionals, or in correctly treating this disease, which has now reached pandemic levels.

The paper proposes the concept of going beyond BMI in diagnosing obesity. In fact, this idea is not new; the article confirms the direction that scientific societies have been pursuing for some time: changing the narrative of obesity, which has long been erroneously defined by kilograms and BMI.

This shift in narrative undoubtedly places obesity where it belongs, within the category of chronic metabolic diseases, and helps clarify its pathophysiology. Practically speaking, it will certainly increase its prevalence if correct diagnostic criteria are applied, but this is the reality, and it is time to acknowledge the elephant in the room because it has been present for a long time. Ideally, body composition studies should be conducted for all patients to properly diagnose obesity.

The Lancet Commission paper proposes various diagnostic criteria based on evidence of excess body fat and/or muscle mass, as well as the presence of complications. It suggests using DXA for body composition analysis, but this technique uses X-rays and is unreliable for obesity (if the weight exceeds 140–160 kg, the machine cannot measure correctly) and does not measure but rather estimates.

Basing the diagnosis of obesity on body composition evaluation is the correct approach—there is no doubt or debate about this among scientific societies and professionals. However, realistically, it is almost impossible to conduct large-scale body composition screenings today, even though we know this is the future. Implementing this approach would require a structural overhaul of consultations, as well as additional human and material resources.

The European Association for the Study of Obesity (EASO) published a new diagnostic framework for obesity in September 2024, recommending body composition studies whenever possible. It also includes practical aspects by adding to the BMI >30 diagnosis the criteria of BMI >25 + waist-to-height ratio >0.5. This easily calculated parameter is a good indicator of cardiovascular risk and metabolic complications, further supporting the idea that obesity is a reality even with BMI <30.

The information on the article reflects the content, in an abbreviated and clear manner. It is a consensus study on the definition and diagnosis of obesity, supported by the results of expert consultation.  

The conclusions of this study are based on data collected with an appropriate methodology and show the need for a paradigm shift in the consideration of obesity as a disease and the methods to diagnose it.  

In this sense, the dense debate of recent years derives from the need to consider obesity as a disease and to provide evidence-based treatments for its management.  

On the other hand, the traditional body mass index, criticized by many as an effective measure of obesity, requires a methodological reinforcement that would be given by the incorporation of other techniques for the correct diagnosis of obesity.  

All this could lead to relevant changes in the health systems of many countries in the world, because the diagnosis would take a little longer (or much longer if it is through DEXA [bone densitometry]) and would require the health systems to provide adequate treatments to combat obesity. 

The published work represents a very relevant step forward based on the evidence already published in this regard.