I’ll probably forgo trying it myself, but given enough idle time, here’s proof that anything can be hacked.
A student in NYU OSIRIS security lab, who is only known for now as b0n0n was given a Microsoft Band (version 1) for a school project that involved figuring out how the Band client software communicated. But, just like the plot for a teen action movie, the assignment turned out to be too easy so b0n0n turned to hacking. What ensued was a full understanding of how to manipulate the Band 1 data.
b0n0n has devised and provided a recipe for modifying any of the code and data in Band 1 update to whatever you want.
Full details here: Jailbreaking the Microsoft fitness band
b0n0n has only tested this against the Band 1, but says it should work the same with Band 2.