Much of What We Know About Obesity Will Change in the Coming Years

People think their weight is under their control: they can eat less, lose weight, and then maintain that loss. Current scientific evidence says this is not true. Strict dieting and/or exercise results in a loss of 5% or more of body weight in only a third of people with obesity. Whatever the intervention, this may last only a year or two.

Not only are obesity treatment strategies changing, but "absolute truths" and recommendations are being reassessed, particularly how doctors advise patients on managing the problem and involve them in treatment. These ideas were presented in two sessions at the 63rd Conference of the Spanish Society of Endocrinology and Nutrition (Sociedad Española de Endocrinología y Nutrición).

Obesity Is Not Simply a Problem of Eating Too Much

"The Future of Obesity Treatment: A Perspective for the 21st Century" was the title of a session featuring Dr. Carel Le Roux, director of the Metabolic Medicine Group at University College Dublin, Ireland. "Much of what we now consider certain about obesity will change over the next few years, and the central question we must answer in this context is whether it is a disease," he said.

"Most specialists believe it is a disease, but that does not mean it is treated as one in practice. We must not forget that there are approximately 220 complications associated with obesity, not only metabolic ones, that also require treatment. The World Health Organization defines obesity as an abnormal excess of adipose tissue leading to impaired health. It is terrible, but it is the best definition we have today. In using this concept, however, we must distinguish two things: evidence that obesity is a disease, and the cultural desire to be fit. In principle, this is not a weak premise, as long as we clearly communicate that the patient is receiving treatment for a disease and emphasize that the main goal is not simply to make them thinner so they will be happier or look better. Assuming that endocrinologists' task is to treat a disease, we must move beyond the idea that our job is to help people lose weight. Weight loss will follow naturally."

Lowering Body Mass Index

"When treating obesity, we must question many of the principles we have always accepted as true," Dr. Le Roux says.

"One is the role of BMI (body mass index). It is undoubtedly a very convenient tool that has been useful in the past, but I do not believe it will remain so in the future. I do not think BMI alone is a diagnosis or an infallible parameter. We should regard it as a screening test. If someone comes to a doctor with a BMI of 30, the first step is therefore to establish a diagnosis confirming whether they have obesity, because some patients with a lower BMI still exhibit the disease."

Dr. Le Roux emphasizes that another principle specialists should reconsider is reducing energy intake and increasing energy expenditure .

"We should think of obesity as a malfunctioning thermostat, and in this sense, noting pathological signs is important. Moreover, we now know it is a neurological disease, or more accurately, a neuroendocrine problem . Because obesity has genetic determinants and 80% of the associated genes are in the brain , brain mechanisms related to obesity—specifically hunger and satiety—must also be considered."

Dr. Javier Salvador Rodríguez, director of Endocrinology and Nutrition at the University of Navarra Clinic in Spain, and Dr. Ignacio Llorente of Nuestra Señora de Candelaria University Hospital in Santa Cruz de Tenerife analyzed future challenges in approaching obesity during a session entitled "Obesity Treatment: Key Points for Today and Tomorrow."

The experts discussed the implications for endocrinologists of viewing obesity as a chronic disease. According to Llorente, this means following patients regardless of the results achieved and recognizing that this chronic nature—long duration, slow evolution, and difficulty treating or achieving remission—requires patients to seek healthcare.

" As endocrinologists, we must believe obesity is a chronic disease and take the leading role in managing it, as we do with other conditions," Dr. Llorente said.

Dr. Salvador emphasized the need to prevent stigmatization  of people with obesity.

"Research shows stigma is destructive to a patient's personality, breaks people down, and leads to marginalization. It also facilitates chronic disease and increases complications. Stigma clearly stems from weight bias , which makes patients think obesity is their own fault. This arises from a failure to understand the problem and the wide range of associated genetic changes. Fortunately, more treatment options are available."

Stigmatization and Treatment Failure

Dr. Llorente continued: "Lifestyle changes are indeed central to obesity treatment, but they are not the only factors in its development. If we focus solely on the patient's attitude and desire to succeed, we are mistaken, because we stigmatize them if their efforts fail."

The fact that "most" patients who change their lifestyle and follow strict diets first lose and then regain weight suggests factors beyond lifestyle, particularly genetics, in the development of obesity.

According to both experts, the evidence leaves no doubt that obesity-related stigma increases complications and makes them more chronic. Healthcare professionals' educational role and conviction are therefore essential.

Advances in drug treatment for obesity offer better prospects for individualized, successful treatment.

"The principal advantage of starting comprehensive obesity treatment early is that it is essential to reducing the chance of developing an associated comorbidity. An important concept here is multimorbidity: simple, involving two other main diseases, or complex, involving four associated diseases."

"Obesity has been shown to be associated with three times more comorbidity than in people without the disease. However, simple multimorbidity in early obesity is 5 times higher than in the healthy population, while in complex obesity it is 12 times higher. A person with obesity aged 55 therefore has the same multimorbidity risk as a person aged 75 without the disease. This is why we must pay attention to trends and movements such as 'metabolically healthy obesity' or 'health at every size,' because they are incorrect. A patient with obesity who is not treated will develop comorbidities."

Salvador highlighted the clear relationship between obesity duration and the development of comorbidities, as in other chronic diseases. Research has shown that the average time between a patient first becoming concerned about weight and consulting a specialist is 6 years .

New Drugs for Obesity Treatment

The researchers also discussed what to expect from new, second-generation drugs. The main benefit would be a greater percentage of weight loss with maximum long-term safety. Some drugs will become available soon, while others have recently been approved by the FDA (US Food and Drug Administration). Although approved to treat obesity and avoid associated complications, they are popularly known as "weight-loss injections." 

• In 2021, semaglutide was approved as a pharmacological treatment for long-term weight management.
• In October 2022, tirzepatide rapidly received approval as a drug to treat obesity.

All these drugs are undergoing phase 3 clinical trials for obesity. Their effects on weight loss and adolescents are being investigated, and cardiovascular safety will also be assessed. An important question is whether these treatments help patients lose weight safely in ways that existing drugs cannot.

Salvador disagreed on this point. In his view, long-term safety guarantees for these obesity drugs have not yet been established. "I believe the advantage of the new drugs, rather than safety, will be a lower proportion of nonresponders in terms of weight loss. These molecules will also allow us to treat comorbidities, such as fatty liver, in ways we never thought possible with another treatment. The message, therefore, is to select these treatments according to the summary of product characteristics."