What to east in the late afternoon..feeling very flat

I am trying to eat healthy, (a few kg off wont harm my bike riding)
So I have a fairly large breakfast, something small at about 11am and again something small at about 1pm (mostly ham /cheese on bread) and then in the afternoon about 3pm I am either famished or I feel so flat that training that afternoon seems like a real big mountain to climb. What would be a good thing to eat during the rest of the day to keep away the hungerpangs but is not to filling. I prefer not to eat bars/ fastfoods so would be looking at something fresh..any sugestions