The vicar at a church I was at previously before moving house always maintained that Sundays were Feast days so during Lent you wouldn't fast. I don't mean full on fast, just that whatever you had given up for Lent you could have / do on the Sundays.
This seems to vary between not just churches but individual people I've spoken to. As it happens, I did maintain my fast last Sunday but not consciously.
What are you doing this year? I'm not sure if it makes a difference depending on denomination but for reference I'm Anglican.