The leftover is a life book.

Food companies are already living in the first sentence. Calorie bands, pack sizes, the quiet hope that a lighter person still buys a treat. That is a volume story, and it is already on this site. The second sentence belongs to a different book. A life insurer does not sell lunch. It sells a promise that pays when the lunch-eater dies. If the drug that shrinks the lunch also stretches the years, the promise gets more expensive. If the person who lost the weight then lapses the policy that was rated for the weight they no longer carry, the book that remains is the book that still needs the drug. It is an underwriting problem.

RGA, Munich Re, and the Society of Actuaries have all, said it is too early to change insured mortality assumptions in a material way. Persistency is the object they keep naming. Munich Re has published a scenario, their model, not ours, of something like two-tenths to five-tenths of a percent of annual mortality improvement over twenty years if the drugs hold and the people stay. Those are small numbers until you compound them across a book that was priced on a different body. Annuity writers feel the same arithmetic from the other side. A longer life is a longer payment.

The BMI print and the in-force print

What the tape is ignoring is the gap between the BMI print and the in-force print. A trial can show weight. A claims file shows who kept paying. Anti-selection is the ugly word for a simple behaviour: the person who no longer looks like the risk they were rated for shops the market, or stops. The book that is left is heavier, older, or less adherent than the brochure. Reinsurers know this language. Equity tapes that treat every GLP-1 headline as a calorie headline do not. Hidden value sits with the life and reinsurance names that are already rewriting applications, not with another rotation through the snack aisle. It also sits with the opposite trade if persistency fails: a drug that people stop is a mortality story that never arrives, and a rating that never gets to be wrong.

The visionary version is that a class of drugs becomes a second underwriting axis, the way smoking did, and that the companies who learn the axis early own a spread the rest of the market still prices as noise. That is a long, almost boring revolution. It happens in application questions, in waiver language, in who gets a preferred class after a year on the pen. If it is true, share prices that only know the factory are reading the factory. The factory matters. The book that has to live with the factory’s output matters more, and it is quieter.