Obesity
Also known as:
Clinical obesity, preclinical obesity, adiposity-based chronic disease
A chronic disease of excess body fat. The 2025 Lancet Commission separates obesity that is already harming the body from obesity that raises future risk.
Written and reviewed by Farhan Tahir, MD · Last reviewed
VIDEO LESSON
What it is
Obesity is excess or abnormally distributed body fat that impairs health. Body weight is regulated by the brain, hormones from the gut and fat tissue, genetics and environment, which is why willpower alone rarely overrides it.
Clinical vs preclinical obesity
The 2025 Lancet Diabetes & Endocrinology Commission defines clinical obesity as excess adiposity that is already causing organ dysfunction or limiting daily activities, and preclinical obesity as excess adiposity with preserved function but higher future risk. It recommends confirming excess fat with a waist measure or body composition, not BMI alone.
Health effects
• Type 2 diabetes and prediabetes
• Fatty liver disease (MASLD)
• High blood pressure and heart failure
• Sleep apnea and knee osteoarthritis
• Several cancers, infertility and mood effects
Treatment
Nutrition, activity, sleep and behavioral support are the base. Anti-obesity medicines such as semaglutide and tirzepatide produce substantial weight loss and health benefits. Metabolic and bariatric surgery offers the largest and most durable weight loss for many people with severe obesity.
Clinical pearls
• Treat obesity like other chronic diseases: long term, without blame.
• Stopping effective medicines usually leads to weight regain.
Key studies and references
Trusted resources
Educational content only, written and reviewed by Farhan Tahir, MD. It does not replace individual medical advice. For sudden chest pain, trouble breathing or stroke symptoms, call 911.
AT A GLANCE
Category
Weight & obesity
Also known as
Clinical obesity, preclinical obesity, adiposity-based chronic disease
Reviewed by
Farhan Tahir, MD
Questions about your own care?
Dr. Tahir’s team offers consults through Youthful Medicine.
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