For eleven years Rosa Nakamura’s care was organised around a single number reported four times a year. It is a useful number. It is also, as her clinician puts it, a photograph of a film.

The fortnightly group ran with the same nine people throughout. Nobody was weighed in front of anybody. Most of the time was spent on what had gone badly.

Maintenance is its own phase with its own skills, and the team treats it as harder than the losing phase rather than as a victory lap.

An average can look excellent and hide a week of chaos inside it.

Illustrative composite

The programme front-loads almost nothing. The first phase changes two things and no more, which most people find insulting for about three weeks and survivable after that.

“I was managing something I couldn’t see,” she says. “Now I can see it. That’s most of what changed.”