Obesity

Obesity is a complex multifactorial disease in which accumulated excess body fat leads to negative effects on health, with its main cause being a long-term energy imbalance between consumed and expended calories. ^[1] It is a chronic metabolic disorder characterized by pathological adipose tissue expansion, chronic inflammation, and neuroendocrine dysregulation that disrupts systemic homeostasis. ^[2] Contrary to being merely a risk factor for other diseases, obesity meets the medical definition of a disease, being a physiological dysfunction with environmental, genetic, and endocrinological aetiologies. ^[3]

The main cause of obesity is a long-term energy imbalance between consumed calories and expended calories, with pathogenesis spanning genetic, epigenetic, social-environmental, and microenvironment factors. ^[1] Visceral adipose tissue is an independent risk marker of cardiovascular and metabolic morbidity and mortality, and ectopic fat deposition contributes to increased atherosclerosis and cardiometabolic risk. ^[4] Sedentary behavior and physical inactivity are significantly associated with obesity, with a positive risk association. ^[5] Obesity, and in particular an excessive visceral fat distribution, drives hormonal, inflammatory, and endothelial alterations that promote hypertension and increased cardiovascular morbidity ^[6]. Obesity-induced chronic, low-grade inflammation, driven substantially by adipose tissue macrophages, promotes insulin resistance and the progression to type 2 diabetes ^[7].

Raised body mass index is a risk factor for noncommunicable diseases such as diabetes, cardiovascular diseases, and musculoskeletal disorders, resulting in a dramatic decrease of life quality and expectancy. ^[1] Obesity has transitioned from a localized health concern to a pressing global public health crisis affecting over 650 million adults globally, as documented by WHO epidemiological surveys. ^[2]

Obesity is rarely an isolated condition and is frequently complicated by severe comorbidities including type 2 diabetes, cardiovascular disease, and non-alcoholic fatty liver disease that collectively elevate mortality risk. ^[2] Overweight and obesity have been independently associated with increased cardiovascular risk, and weight reduction effectively reduces major cardiovascular events. ^{[8] [9]} Interventions involving resistance training and caloric restriction are the most effective for reducing body fat percentage and whole-body fat mass, while resistance training helps preserve lean mass during weight loss. ^[10]