In his infinite wisdom, health secretary Alan Johnson has said obesity is potentially as great a threat as climate change.

Now I must be terribly ill-informed because I hadn’t realised that, in addition to causing death, obesity had the potential to create hundreds of thousands of refugees, the extinction of plant and animal life (is that because we will eat them?!) and change the topographical face of the planet as we know it.

I guess I’ve underestimated obesity.