What do Buddhists say about illogical self sacrifice? I don't want to sound Vulcan, but I mean self sacrifice which is out of proportion, what do Buddhists say about it? So as an example, going on a dangerous hunger strike, in order that your well fed friend has another loaf of bread.

I got thinking about this via dying for the "one you love", but obviously that sort of thinking is off in Buddhism.
Here are three possible angles to look at it from:


A genuinely selfless action can be a wholesome act of generosity and compassion. But...
A sacrifice of any kind can be wholesome or unwholesome depending on the deep motivation. If the action is meant to manipulate or punish others (or even yourself), it will have bad results. Sometimes we are not aware of how we can have selfish motives for apparently selfless acts, so we have to be careful.  
One of the "fetters" that binds a being to endless rounds of rebirths is attachment to "rites and rituals". So fasting as an attempt to propitiate fate or karma or God, or to achieve some kind of magical outcome, is useless. Prior to his enlightenment, the Buddha spent years starving himself thinking that that was the route to liberation from suffering. His motivation was pure, but he realized that it was pointless to destroy his body.