How does a Fitness Fanatic Fast?

For many people, today is Ash Wednesday, a special day that invites them to fast. The spirituality of this Catholic holy day, as well as that of Lent, the season it initiates, is well beyond the scope of this post, though I'd be more than happy to elaborate on it if anyone is interested.
Suffice it to say for now that on Ash Wednesday, Catholics go without food to remind themselves of their utter dependence on God, of their on mortality, of entering into the 40 day journey that leads to the death and resurrection of Christ, as well as an expression of solidarity to the millions of people who go without food today out of poverty, not of choice. These are all good, strong reasons to practice this spiritual discipline.
The problem I am encountering is a clash of this spirituality of fasting with the culture of diet and fitness that has become a lifestyle for me. How should I define fasting when my everyday approach to food is already limited, regimented, specified? Giving something up is not just a lenten thing for me; it has defined my diet for the past year or so. How do I distinguish Lent then?
A friend suggested to fast by fasting from dieting and exercising for a day each week. I like in her suggestion the broad definition of fasting, and pinpointing an area in one's life that could use some simplification. Nonetheless, I am drawn to figuring this out in terms of the original intent of the practice of fasting, which involved giving up food in some capacity. I don't want my practice of fasting to be so subjective that it becomes disconnected from the actual practice.
I continue searching to figure out the deep spirituality that connects food, hunger, fulfillment, and God...