Oh, so there is also a 20:4 diet. This must be the one that I am on. Who would have thought it thirty years ago. Ha. I like these numbers, too. Look.

204 = 2(102) = 4(51) = (1 + 3)51 ---> 351;

204 = (1 + 3)*3*(7 + 10) ---> 137 and 197.

Anyway, part of the "logic" of eating once a day, a mini-feast, everyday, is that we shit once a day, so, why not eat once a day? Like a snake eats once a week, to shit once a week.

20:4

This involves a 4-hour eating window and a 20-hour fast. For example, you might eat between 2:00 pm and 6:00 pm every day and fast for the other 20 hours. This would involve eating either one large, lengthy meal or two smaller meals within this period.

https://www.dietdoctor.com/intermittent-fasting
Now I wonder what numbers for an 18:6 diet.