I'm muslim and I do fast on mondays and thursdays. I feel much better during the day and also more focused. Following as how it is done in islam (no food, no water) I take breakfast before the sunrise (right now where I live is around 5am) and then after praying (similar to meditation in terms of benefits) I start to work.

I can think really clearly vs the days that I don't fast and also I would say that my productivity is higher in terms of what I achieve. It has the downside that at 5PM or around I'm already without energy and I stop working compared to normal days when I'm okey up to 11pm.

I also pray 5 times a day as is usual, I'm not sure if that is relevant as afaik it has been found to have similar effects to meditation.

Finally I eat dinner and drink around 9PM