[_steady]

Water is 27x more thermally conductive than air, so standing in water burns 27x more calories than air of the same temperature. So, go cold water swimming!

(Plenty of normal healthy ways to lose weight but that's the weirdest hack I can think of)

[davewasthere]

Yeah, I remember reading something about measuring Michael Phelps' energy input/output and he would have been in a massive surplus, except for the fact he was in cold water so much - and the energy required to keep himself warm made up the balance.

[mvc]

Drinking more of the stuff is generally good advice too.