int to float conversion produces a warning?

It's surprising for me to see that even when the value can be converted, an int to float conversion always give a warning. Why is this?

int i = 0;
float f = 0; // warning here

// I thought this was an implicit conversion,
// meaning it is convertible with no warnings.
f = i;      // another warning here

The warning is:

warning C4244: '=' : conversion from 'int' to 'float', possible loss of data