Short answer: The claim is nuanced and often misused. Eating disorders are among the most lethal mental illnesses, with anorexia nervosa having one of the highest mortality rates of any psychiatric disorder, but whether they are definitively the "second deadliest" after the opioid crisis varies by country, data source, and what is being measured (mortality rate, absolute deaths, or case-fatality). In many reputable sources, eating disorders are described as having a mortality rate second only to opioid use disorder among psychiatric conditions, but context matters and not all sources agree on the ranking or on which condition is second. Context and nuances

• Mortality risk is high across eating disorders, particularly anorexia nervosa, due to medical complications from malnutrition, cardiovascular problems, and suicide risk. This is supported by multiple clinical studies and reviews.

• Some organizations and articles explicitly state that eating disorders have the second-highest mortality rate of psychiatric illnesses behind opioid use disorder. However, this framing depends on the dataset and time period used in the analysis.

• Other sources emphasize that while mortality is substantial, the exact ranking can differ, and public-health messaging may oversimplify the comparison.

If you’re looking for a precise, up-to-date statement for a specific context (country, year, or dataset), I can pull the latest credible sources and compare their wording and data to give you a clear answer with citations.