Understanding Obesity: A Chronic Multisystem Disease and its Complications
Obesity is a highly prevalent chronic multisystem disease characterized by abnormal and/or excessive accumulation of body fat that poses a significant risk to health and quality of life. Globally, the number of adults living with obesity has more than doubled since 1990, with over 890 million people affected in 2022. This condition is associated with a shortened life expectancy due to a wide array of adverse health outcomes.
Epidemiological data strongly link increased body weight and parameters of central fat distribution to an escalating risk for numerous diseases. These include, but are not limited to:
- Type 2 diabetes
- Cardiovascular diseases, such as myocardial infarction, heart failure, atrial fibrillation, and stroke
- Fatty liver diseases (Metabolic Dysfunction-Associated Fatty Liver Disease – MAFLD)
- Hypertension (high blood pressure)
- Obstructive sleep apnoea
- Osteoarthritis
- Mental disorders (e.g., depression)
- Certain types of cancer
While excess fat accumulation is a hallmark, the individual risk for developing cardiometabolic and other obesity-related diseases cannot be entirely explained by increased fat mass alone. Instead, dysfunction of adipose tissue (fat tissue) is increasingly recognized as a crucial mechanistic link between obesity and adverse health outcomes. This understanding highlights that some individuals with obesity appear to be protected against the premature development of cardiometabolic diseases (known as “metabolically healthy obesity”), while people with normal weight might still develop typical obesity-related conditions due to adipose tissue dysfunction, particularly with predominant visceral fat distribution. Key mechanisms linking impaired adipose tissue function include adipocyte hypertrophy, altered cellular composition, limited expandability of safe subcutaneous fat stores, ectopic fat deposition in various organs, and inflammatory processes releasing pro-inflammatory, diabetogenic, and atherogenic signals.
Recognizing obesity as a chronic, complex, and progressive disease, it is crucial that treatment strategies are comprehensive and patient-centered. Evidence-based weight loss interventions, encompassing behavior changes, pharmacological approaches, and surgical therapies, have consistently demonstrated beneficial effects on obesity-related complications. Even moderate weight loss can lead to significant improvements in health, quality of life, and a reduction in the risk for obesity-related diseases. Newer pharmacological interventions, such as incretin-based therapies (e.g., semaglutide and tirzepatide), have revolutionized treatment by achieving substantial weight loss and improving glucose parameters, potentially narrowing the efficacy gap with obesity surgery.
Reference for this article: Blüher, M. (2025). An overview of obesity-related complications: The epidemiological evidence linking body weight and other markers of obesity to adverse health outcomes. Diabetes, Obesity and Metabolism, 27(Suppl. 2), 3–19. https://doi.org/10.1111/dom.16263
