The global obesity Atlas estimates that more than 4 billion people worldwide, 51% of the global population, suffer from this disease. Out of the 41 million annual deaths in adults from non-communicable diseases, five are due to a high BMI above 25. Nearly four million of them are solely due to diabetes, strokes, coronary heart disease, and cancer. A high BMI is responsible for over 120 million person-years lost each year due to these four obesity-related conditions.
A problem in which "the role of obesity has been minimized," claims Andreea Ciudin, endocrinologist and board member of the Spanish Society for the Study of Obesity (Seedo). And she insists that "it has been considered a condition related to lifestyle and lack of willpower of individuals." Without directly linking it to the presence of "a disease that is different" and that "obesity can exist even in people who were previously considered thin or of normal weight," emphasizes the coordinator of the Comprehensive Obesity Treatment Unit at Vall D'Ebron Hospital.
More than 50 experts in the field have reflected on these notes and the new considerations of obesity, which they have outlined in an article in The Lancet Diabetes & Endocrinology. "This consensus, carried out by highly prestigious individuals in the world of obesity, diabetes, metabolic syndrome, obesity surgery, such as Dr. Rubino [Francesco Rubino, the commission's president], establishes a systematic review, reflection, to propose a new perspective, a new approach," explains Clotilde Vázquez, head of the Endocrinology and Nutrition Department at the Jiménez Díaz Foundation (FJD).
Rubino, from King's College London (UK), states that the paradigm about obesity needs to be changed. "The question of whether obesity is a disease is wrong because it presupposes a simplistic scenario of all or nothing, where obesity is always a disease or never is. However, evidence shows a more complex reality. Some people with obesity can maintain normal organ function and overall health even in the long term, while others show signs and symptoms of a serious disease immediately."
Among the most important changes are new ways to diagnose obesity and its stages. BMI is not everything, and the scale number is not definitive, "it has been wrongly defined as such", argues Ciudin. What is important then? "The excess of adiposity and its clinical impact," emphasizes Vázquez.
Robert Eckel, from the University of Colorado Anschutz Medical Campus (USA) and a commission member, argues that relying solely on BMI to diagnose obesity is problematic, "since some people tend to store excess fat around the waist or in and around organs, such as the liver, heart, or muscles, which is associated with a higher health risk than when excess fat accumulates under the skin of the arms, legs, or other areas of the body." However, he comments that "people with excess body fat do not always have a BMI indicating obesity," meaning that their health problems may go unnoticed. Additionally, some people have a high BMI and a high amount of body fat but maintain normal organ and bodily functions, without signs or symptoms of active disease."
Given the complexity of the situation and at a time when therapeutic approaches are becoming simpler thanks to new pharmacological proposals developed by the industry (and those yet to come), such as Wegovy and Mounjaro, "our rethinking acknowledges the nuanced reality of obesity and allows for personalized care," adds Rubino. "This includes timely access to evidence-based treatments for individuals with clinical obesity, as appropriate for those with preclinical and clinical obesity."
What are the disease stages?
There is an ongoing debate among clinicians and policymakers about the current diagnostic approach to obesity, which is prone to misclassifying excess body fat and misdiagnosing the disease. These ideas are transferred to society, which sticks to the limits of the scale and BMI without considering whether their body hosts harmful fat or not.
In fact, this concept is not new, assures the Seedo spokesperson. "This article confirms the direction taken some time ago by scientific societies to change the narrative of obesity, which has been wrongly defined for a long time by the number of kilos and BMI." At the same time, Ciudin emphasizes that "this change in narrative undoubtedly places obesity where it deserves to be, among chronic metabolic diseases, and helps understand its pathophysiology."
Practically speaking, explains the endocrinologist from Vall D'Ebrón, "its prevalence increases when the correct diagnostic criteria are considered, without a doubt, but this is the reality and time to acknowledge the elephant in the room because it exists, has existed for some time. Ideally, body composition studies should be conducted on all patients for a correct diagnosis of obesity."
This distinction is made between preclinical and clinical obesity. The former refers to a condition of obesity with normal organ function. Individuals living with preclinical obesity, therefore, do not have an ongoing disease, although they have a variable but generally high risk of developing clinical obesity and other non-communicable diseases in the future, such as type 2 diabetes, cardiovascular diseases, certain types of cancer, and mental illnesses, among others. Therefore, they should receive support to reduce the risk of developing potential diseases.
The latter is a condition of obesity associated with objective signs and/or symptoms of reduced organ function, or significantly reduced ability to perform standard daily activities, such as bathing, dressing, eating, and maintaining continence, directly due to excess body fat. Individuals with clinical obesity should be considered patients with an active chronic disease and should receive appropriate management and treatment.
Vázquez comments that this review, "a reflection of a new approach," requires a diagnosis of excess adipose tissue. "They propose that obesity, even with excess fat, should actually be considered a disease if that excess fat is already causing organ damage. For example, fatty liver, heart failure, widespread osteoarthritis, or diabetes."
But they do not overlook that previous stage. "They are very critical and prompt reflection among the entire professional community dedicated to obesity, so that, in those other cases where there is excess fat, hence a diagnosis of obesity, we talk about preclinical obesity when there is no organ or tissue damage yet," highlights Vázquez.
This point is "crucial for health strategies, professional care, treatment. In the case of preclinical obesity, they advocate for caution in considering it a genuine disease, but rather a situation that can lead to disease, and to prevent it, certain measures must be taken. In contrast, in the case of obesity with already damaged organs, tissues, functions, systems, we would be talking about a true disease caused by excess fat tissue," emphasizes the head of the Endocrinology and Nutrition Department at the Jiménez Díaz Foundation.
Data requiring a paradigm shift
Three-quarters of preventable deaths and illnesses in adults occur in middle-income countries. In short, most people who suffer and die from non-communicable diseases (NCDs) associated with obesity have an underlying high BMI, and most of these deaths occur among individuals in less resourceful environments and developing countries, as reported by the Obesity Atlas.
Due to their high BMI, these 750 million children are at greater risk of experiencing early signs of non-communicable diseases while still in childhood. By 2035, it is estimated that 68 million children will suffer from high blood pressure due to their high BMI, 27 million will live with hyperglycemia due to their high BMI, and 76 million will have low HDL cholesterol due to their high BMI. The symptoms of these precursors to serious diseases are largely invisible, but children will enter adulthood already on the path to experiencing strokes, diabetes, and heart disease.
Despite efforts to address this issue, without significant and coordinated action, obesity rates will continue to rise, and more and more people will die prematurely from obesity or from diseases attributable to obesity. Furthermore, non-communicable diseases associated with obesity, which previously only affected adults, are becoming increasingly common among children.