That was what I did when I was trying to lose weight. I ate subway sandwiches (different variety without cheese) for 2 years - every evening. Mornings were just a plate full of fruits and lunch was variety of typical foods but small portions. Combined with running thrice a week + Muay Thai, I went from 82kgs to 62kgs in three months and stayed around that for a long time.

It is hard to keep up though - I eventually stopped the eating/exercise regime and gained a significant portion of the lost weight back.