It's non-availability causes fat businessmen and overweight chavs (the airport's predominant clientele) to climb stairs, therefore losing body-mass.
Over 12 months these little weight losses all add up to reduced take-off weights.Turn off the moving walkways too. In fact, remove them completely.
Even better for the weight loss regime, let's make a suggestion that they are switched on, just in the opposite direction so even more effort and huffing and puffing required to make it to the gate/baggage hall
!!