Lots of meat in supermarkets has been injected with water. It bulks up the meat to look better, makes it weigh more, and most worryingly of all it is legal. I cant remember what it is but a certain amount of water is legally allowed to be injected. Especially common in poultry. This is just another reason (added to traceability of the meat, hanging time, quality, flavour and packaging properly (not cling wrapped)) why everyone should buy meat from a local butcher.