I commute 30 miles a day and do this:-
Pre Morn Commute: Cup of coffee
At work: before my shower 1 glass of nesquik with soy milk
after shower bowl of museli
Snack: rice cakes and fruit
Lunch: wraps with filling of some sort, crisps and a choccy bar
Before evening commute: Fruit or something
It owrks for me and drinking shed loads of water helps too.