Ten minutes after dinner

Most of us know the slump. Somewhere around four in the afternoon the eyes go heavy, the concentration goes, and a biscuit appears. We put it down to the day, or the meeting, or our age.

We put it down to lunch. When you eat, sugar goes into the blood, and if you then sit still it stays there longer and higher than it should before the body gets round to dealing with it. The higher it goes the harder it falls, and the fall is the slump.

A ten-minute walk after eating changes that. Muscles that are moving take sugar straight out of the blood to use, so the peak is smaller and the fall is gentler. It is not exercise in any sense you would notice. Round the block, down the road and back, a lap of the car park at work. Ten minutes, straight after the plate goes in the sink.

Do it after dinner as well and the evening changes too: better sleep, less picking at things in front of the television. It is the closest thing we know to a free lunch, and it is literally about lunch.