Leggi l’articolo in italiano

March 4 marks World Obesity Day, an important occasion to reflect on one of the greatest public health challenges. But what exactly is obesity? The term derives from the Latin obedere, meaning “to eat a lot” or “to devour,” leading to weight gain and, consequently, fat accumulation. Since ancient times, the term obesity has been associated with increased body weight, particularly fat. However, it is not just an aesthetic issue—it is a real disease with serious consequences for health and quality of life.

HOW OBESITY IS MEASURED?

For centuries, weight has been measured in relation to height to determine whether a person is normal weight, overweight, or obese. The Body Mass Index (BMI) is commonly used, calculated by dividing weight (kg) by height squared (m²). According to guidelines, 18.5 to 24.9 is considered normal weight, 25 to 29.9 is overweight, and 30 and above are classified as obese.

But who established these numbers? They originate from studies conducted by insurance companies interested in estimating health risks to adjust policy prices. Those with a BMI between 18.5 and 24.9 have the lowest risk of mortality and morbidity, whereas the risk increases exponentially beyond a BMI of 30.

IS BMI REALLY ENOUGH?

For years, experts have understood that BMI alone is not sufficient for diagnosing obesity at the individual level, despite its usefulness in large-scale assessments. It does not distinguish whether weight gain is due to excess fat or other factors, nor does it indicate where the fat is located. Obesity is not just about extra pounds—it is a dysfunction of adipose tissue. It becomes particularly dangerous when fat cells accumulate viscerally, filling to their storage capacity. Excess fat then spills over into other organs such as muscles, heart, and liver, with potentially serious health consequences.

CLINICAL OR PRECLINICAL OBESITY? A NEW PERSPECTIVE

Recently, the Lancet Commission, consisting of 56 global experts from various medical fields—including endocrinology, internal medicine, surgery, biology, dietetics, and public health—has proposed a new approach to diagnosing obesity. This method goes beyond BMI, incorporating other measurements to more accurately evaluate the presence and distribution of body fat. In addition to BMI, experts suggest using:

• Waist circumference: measures abdominal fat accumulation.
• Waist-to-hip or waist-to-height ratio: compares waist circumference to hips or height, providing insight into fat distribution.
• Direct fat tissue measurement: techniques such as DEXA (Dual-Energy X-ray Absorptiometry) or bone density scans precisely quantify fat mass.

Furthermore, the commission has established 18 diagnostic criteria for assessing obesity based on objective pathological indicators. These include: shortness of breath, heart failure, knee or hip pain, osteoarticular alterations, and dysfunction of various organs (kidneys, liver, respiratory system, nervous system, urinary system, lymphatic system, reproductive system).

Only individuals displaying one or more of these signs or symptoms are classified as having “clinical obesity”, a chronic, progressive, and recurrent disease. For individuals with increased fat mass but no clinical symptoms, the commission suggests the term “preclinical obesity”—a condition where people may maintain normal organ function and good health for several years. However, they remain at high risk of developing clinical obesity in the future.

HOW TO INTERVENE? A PERSONALIZED STRATEGY 

This new classification allows for a more differentiated and personalized therapeutic approach, ensuring timely treatment for individuals with clinical obesity while implementing risk-reduction strategies for those with preclinical obesity.

In both cases, people with any form of obesity should be considered at risk, even if preclinical obesity does not yet show significant clinical symptoms. A potential approach is active surveillance, a protocol already used for low-risk prostate cancer patients. This strategy includes scheduled patient monitoring and targeted lifestyle interventions to prevent the disease from worsening.

HOW CAN WE STOP THE EPIDEMIC?

Obesity is a complex phenomenon that cannot be reduced to a simple number on a scale. It requires an integrated approach, based on individualized evaluation, to prevent millions from developing avoidable complications. So, what can we do? Prevention, nutritional education from an early age and physical activity must be the foundation. A key factor in obesity prevention is the Mediterranean diet, recognized as one of the healthiest dietary patterns in the world. Rich in fruits, vegetables, whole grains, fish, and extra virgin olive oil, it not only helps control weight but also protects heart health and metabolism.

Perhaps the key to fighting obesity is not just counting calories or stepping on the scale frequently, but returning to a balanced, mindful, and enjoyable way of eating.

Read Mediterranean Diet: A Heritage to Defend>>>