I know I'm a little late here, but intermittent fasting is actually a pretty trendy thing in the valley right now because of increased mental clarity.

I didn't start it for the mental side effects, but I haven't noticed any strong negatives during my day job. I get 4-6 hours of meaningful work done and then my brain is about finished like most days.

Many people who do IF actually suggest working/playing to keep your mind off the hunger as it's easier to ignore when you're busy.