If you're fasting to lose weight, then you're probably also calorie restricting at those other meals anyway, and so eating later in the day and taking the "food coma" into the afternoon is better for productivity than in the morning (for me).

I went through a phase of only eating lunch at 12pm - so I'd be fasting for nearly 24 hours daily (of course, tied alongside severe calorie restriction meant I was losing weight at an unhealthy rate). Whilst probably horrendous for me long-term, and raising quite a few questions about my general health, I felt fantastic doing that. Some days I even felt like just randomly running along the pavement I had that much energy.

So, there might be some science behind it, honestly not sure - but that anecdata does make it a compelling thing to try.