I'm 6' 0''/175 lbs. - hair color, or what used to pass for hair color (think "Paul Newman"...without the looks), is irrelevant. ;)
The primary function of the liver is to metabolize fat for energy, by far the body's greatest source of energy.
Wanna be bored? 9 calories/gram for fat as opposed to 4 calories/gram for carb's and protein.
When the kidneys are forced, beyond their capabilities, to process the fluids in the body into something usable, the liver kicks in to assist. (Hence, the connection that alcoholics have between kidney and liver disease, among other things unpleasant.)
When the body is sated with pure water, tap water being OK - depending on where you live, of course - the kidneys do their jobs and the liver does its job.
Of course, a little "getting off your arse" doesn't hurt either. :D