<i>Feeling hungry usually kills my concentration especially in early stages (I remember first day being the worst and later you sort of get used to it). And in general I feel weaker and drained.</i><p>This is the point, isn&#x27;t it? For me, not only fasting does not make me weak or unconcentrated - quite the opposite. My fasting days are the days I&#x27;m feeling the best. And the added benefit is that I have so much more time because I don&#x27;t need to worry about cooking and eating. Oh and the opposite too ... :)<p>Why is it though? I think it is just because I came over the initial obstacle, became used to fasting and now it is just as natural to me as normal eating pattern.<p>Was it worth it, though? After all, there is little chance I will actually experience real shortage of food so my &quot;skill&quot; is useless in practice. Well, one thing is that there is a growing number of studies that show health benefits. The other is that I am sure it carries over to other aspects of life - i.e. being trained to voluntary restrain from food, it&#x27;s easier to restrain from impulse purchases or apply any other restrictions. Plus, I believe (with no studies that I know of to support that) that having a body that is more &quot;robust&quot; - that can operate equally well both during feast and famine - is a positive thing.