Pssst. Do you want to know the real cause of obesity? It's nothing to do with people gorging themselves on sweets and fizzy drinks, or eating Big Macs, apparently, but rather the curse of the thick-cut sliced sarnie.

This revelation was made in a House of Lords debate where Baroness Gardner of Parkes, a member of the All-Party Group on Obesity, called for a crackdown on thick-cut bread. "Why is it that in London you can hardly find a thinly sliced or medium-sliced loaf of bread and any sandwich in a supermarket is made with thick bread?" she asked. "There should be more pressure from the FSA to take us back to normal-sized bread instead of these super-sized sandwiches."

The Lords used medium-sliced, she said, but the Commons used thick. Could this explain John Prescott's waistline?