Definition and Diagnostic Criteria of Clinical Obesity (Lancet Diabetes & Endocrinology Commission)
by Francesco Rubino et al. · The Lancet Diabetes & Endocrinology
This is the current reference framework for treating obesity as a disease. 2025 consensus report from 58 international experts separating preclinical obesity (excess fat, organs working normally) from clinical obesity (a chronic illness with organ dysfunction). It sets diagnostic criteria beyond BMI and explains what each diagnosis means for treatment.
More resources on Obesity Medicine & GLP-1 Drugs
Burn: New Research Blows the Lid Off How We Really Burn Calories, Lose Weight, and Stay Healthy
An evolutionary anthropologist presents doubly labeled water studies of energy use in the Hadza and other populations. He explains the constrained energy expenditure model, why exercise alone rarely produces lasting weight loss, and how diet and metabolism interact.
The Hungry Brain: Outsmarting the Instincts That Make Us Overeat
A neuroscientist explains how the brain controls appetite and body fat, covering the hypothalamus, leptin, reward and satiety signals, and why modern food environments lead to overeating. The book is grounded in obesity research and gives background for why appetite-targeting drugs work. This is the best book-length introduction to how appetite and body weight are regulated.
Daniel Drucker: Illuminating the GLP-1 Drugs' Break Out (Ground Truths)
This is the best free, non-technical explanation of how GLP-1 drugs work, given by someone who helped discover the biology. It covers mechanism, muscle loss and stopping treatment without influencer or telehealth bias. It dates from April 2024, so it predates some newer trials, but the explanation of how the drugs work still holds. Eric Topol interviews Daniel Drucker, one of the scientists who discovered how GLP-1 works, about how the drugs reduce appetite through the brain, lean-mass loss, what happens after stopping, and the anti-inflammatory effects linked to heart, kidney and liver benefits. A free transcript is included.
Semaglutide and Cardiovascular Outcomes in Obesity without Diabetes (SELECT Trial)
Cardiovascular outcomes trial of semaglutide 2.4 mg in 17,604 adults with heart disease and overweight or obesity but no diabetes. It found 20% fewer heart attacks, strokes and cardiovascular deaths, the first such result for an obesity drug. SELECT is the key trial showing they reduce serious health events, which is essential for judging benefits beyond the scale.
Tirzepatide Once Weekly for the Treatment of Obesity (SURMOUNT-1 Trial)
This is the original evidence for the most effective approved obesity drug. Read alongside STEP 1, it shows how a dual GIP/GLP-1 agonist compares with semaglutide alone. 72-week phase 3 trial of tirzepatide, a drug that activates both GIP and GLP-1 receptors, in 2,539 adults without diabetes. Mean weight loss was 15% to 20.9% depending on dose, versus 3.1% with placebo, with side-effect data for each dose.
Once-Weekly Semaglutide in Adults with Overweight or Obesity (STEP 1 Trial)
This is the original evidence for semaglutide's weight-loss effect, and nearly every guideline and review cites it. The main 68-week randomized controlled trial of semaglutide 2.4 mg in 1,961 adults without diabetes. Mean weight loss was 14.9% versus 2.4% with placebo. The paper also reports gastrointestinal side effects and why participants stopped treatment.