I have heard that TG can stand still for over a 1000 years. So what do they eat? Or do the saurus almost never eat? In like a thousand years or more? It doesn't add up.
Unfortunately we put more thought in GW fluff than they do. They don't get very far past the Rule of Cool, you did inspire me to add the Slann having a spell to free themselves and their guards of the need for sustenance temporarily in my last installment of the story I'm working on.
well if you look at it one way, there are an awful lot of animals who barely ever eat and when they do its very little. so perhaps because they are just stood still for so long they can survive for centuries off practically nothing. so maybe when they do eat when they arent stood around and have full meals for.. enjoyment.. i suppose? its enough to keep them going for centuries.
Crocodiles and Alligators usually only eat once a week. According to some people they can go for up to 2 years surviving off the calories stored in their tails. So for Temple Guard you could assume that they could go for a few months fairly easily, especially if you use "magic" excuse.