I hear the 10-15% of the body weight all the time. I know my girl just two weeks ago took nearly 19% of her body weight without a problem and ate again a week later. I prefer small meals though so thats what Im gonna go with from now on. It really depends also on the size of the snakes cause obviously giving a 2000 g snake a 300 g rat might be a little excessive lol. Just take in your scale when you get the rat and pick and choose till you get the right size.