Cantaloupe's hardware sends a message any time a vending machine door opens.

FORBES: Cantaloupe System brings order to vending's chaos.

"I feel we are trying our hardest to promote values in our children and yet at the same time the vending machines are actually promoting unhealthy eating, " he added.

BBC: Vending machines in schools often sell high-fat products

You would have to spend a lot of time in hospital waiting rooms for the contents of the vending machines to make much of a difference to your weight.

BBC: Vending machines 'undermine' hospitals' good work'