Figure 2.

Friendship connections among programme members. We denote members who lose weight by circles, and those who gain weight by triangles. We colour the symbols according to total per cent weight change. The vast majority of networked members (74%) belong to a single cluster, the so-called ‘giant component’. Fifty-four per cent of the members in the giant component lost 5% or more of their baseline body weight by their sixth month in the programme.