Programming and Dieting?

duncan bayne asks: "I've been using the Hacker's Diet to lose weight. What's interesting to me is how hard it is to focus on a complicated task when my body is busy running out of energy. I'm having to pay careful attention to snacking - eating enough that I don't 'fade out' in the afternoon, yet not so much that I exceed my daily kilojoule allowance. This got me to thinking about energy levels of those who aren't dieting. Do you find yourself correcting 'fade' by snacking (careful or otherwise) as you work?"