"I really need to lose some weight." It is a phrase many people say when the numbers creep up on the scale. Most people think of obesity as a matter of appearance or self-discipline, but medically it is a chronic disease driven by a complex interplay of causes. Excess body fat in particular can raise the risk of diabetes, cardiovascular disease, fatty liver disease and other conditions, making a comprehensive assessment of one's health — not just weight loss — essential.
The criteria used to diagnose obesity are also evolving. In January 2025, an international expert commission proposed new diagnostic standards in The Lancet Diabetes & Endocrinology, arguing that body mass index alone is insufficient and that the actual impact of excess body fat on organ function and daily life must also be evaluated.
The commission divided obesity into two categories: "clinical obesity" and "pre-clinical obesity." Clinical obesity refers to a state in which excess body fat has caused measurable impairment of organ or tissue function, or has significantly limited a person's ability to carry out daily activities. Pre-clinical obesity, by contrast, describes a state in which such functional impairment has not yet been confirmed but the risk of future disease is elevated — requiring management tailored to individual risk levels. The framework reflects a broader shift toward assessing obesity by its actual impact on health rather than by weight figures alone.
Obesity is also emerging as a pressing public health concern in South Korea. According to a fact sheet published by the Korean Society for the Study of Obesity, the prevalence of obesity among Korean adults is high, with the condition particularly pronounced among men. The growing number of people with obesity signals not merely that more people are gaining weight, but that preventing and managing obesity-related chronic diseases has become increasingly urgent.
One of the primary ways obesity affects health is through the accumulation of visceral fat and changes in metabolic function. Excessive visceral fat can increase insulin resistance and trigger chronic inflammatory responses. These changes affect blood sugar, blood pressure and blood lipid levels, raising the risk of type 2 diabetes, hypertension and dyslipidemia.
The liver and cardiovascular system can also be affected. Obesity is a major risk factor for metabolic dysfunction-associated steatotic liver disease, and in some patients the condition can progress to steatohepatitis and liver fibrosis. The combination of hypertension, dyslipidemia and other risk factors can also heighten the danger of cardiovascular events such as heart attack and stroke.
Beyond these, excess body fat is associated with an increased risk of certain cancers, including colorectal cancer, postmenopausal breast cancer and endometrial cancer, and it also contributes to obstructive sleep apnea and knee osteoarthritis. Evaluating obesity therefore requires looking beyond weight and BMI to assess the risk of comorbidities — including blood sugar, blood pressure, lipid levels, liver function and sleep.
This is also why obesity cannot simply be attributed to a lack of willpower. Body weight is influenced not only by food intake and physical activity but also by genetic factors, hormones that regulate appetite and satiety, sleep and stress. When a person loses weight, physiological responses that regulate energy expenditure and appetite can make it harder to keep the weight off — which is why weight regain can occur even when lifestyle changes are sustained.
The foundation of obesity treatment is dietary management, regular physical activity, and attention to sleep and lifestyle habits. Losing just 5 to 10 percent of initial body weight can generally be expected to improve blood sugar, blood pressure and metabolic health. However, when lifestyle changes alone are insufficient or obesity-related complications are present, pharmacological treatment may be considered depending on the patient's condition.
Drugs that act on appetite and satiety regulation — including semaglutide and tirzepatide — are now being used in obesity treatment. Clinical trials have confirmed significant weight loss in some dosage groups and patient populations, and certain drugs have also been reported to offer additional clinical benefits, such as reduced cardiovascular risk, in defined patient groups. Because treatment efficacy, side effects and eligibility criteria vary by drug and by the patient's health status, the decision to pursue pharmacological treatment should be based on evaluation by a specialist.
For patients with severe obesity or serious obesity-related complications, bariatric and metabolic surgery may also be a treatment option. What matters most is not prioritizing any single approach — whether medication or surgery — but developing an appropriate treatment plan that takes into account the degree of obesity, comorbidities and the course of prior treatment.
In South Korea, a BMI of 25 or above is generally classified as obesity. However, health risks can vary even at the same BMI depending on body fat distribution, metabolic status and comorbidities. If hypertension, diabetes, dyslipidemia or fatty liver disease is identified alongside obesity, it is advisable to consult a physician to assess for complications and review necessary treatment options.
The goal of obesity treatment is not simply to lower the number on the scale. Reducing health risks from excess body fat, managing comorbidities and sustaining long-term weight loss are what matter most. Achieving that requires a comprehensive assessment of metabolic health and comorbidities — not just weight and BMI — and a treatment plan tailored to the individual's condition.
"Obesity is not simply a problem caused by overeating or insufficient exercise — it is a chronic disease in which genetic, hormonal and environmental factors interact in complex ways," said Bae Ji-hun, vice director and endocrinology specialist at Myeongjin Diagnostic Radiology and Internal Medicine Clinic. "Rather than focusing solely on weight loss, it is important to monitor the risk of comorbidities such as diabetes, hypertension and fatty liver disease, combine medical treatment when necessary, and manage the condition over the long term."
kty@heraldcorp.com
