Feeding time at the zoo?

Spencer has suddenly started eating loads and loads of food. At breakfast he has upped his one bowl of cereal to two. At lunch we don't always have much time as he goes to school at 12:20 but at dinner he has seriously been filling a hollow leg. I often cook and Spencer has in the past eaten a couple of bites and been satisfied. The other night, he ate three helpings of a brand new dish I made. Now this is weird because he normally sniffs and picks at anything new. In the end I estimate he ate about as much as Gary and I did. I made a risotto the other night and he also ate a second helping and has since asked me to cook it again. He has not cut back on his snacks at all. He can usually put away a piece of fruit, a granola bar, some fish crackers, and sometimes some chips in between all his meals. Tonight we ate tacos and often he is full after one or two at the very most. He inhaled three with no problems whatever. Do five year olds go through growth spurts? Leia doesn't seem to have changed her food intake at all over the last few years. I didn't think he would stay stuck at 37lbs for ever but what if he just elongates like a string bean?