Interesting. I am assuming that is nominally "one ordinary peasant's rice consumption", not "enough rice to live on". One gō appears to be about 5 ounces/150 grams, and that is about 550 calories, or 25% of a nominal daily calorie need. One can quibble with the exact numbers - smaller stature Japanese feudal peasants, but heavier physical demands, etc.

It works out to 25% of the calorie need, ironically close to the amount supplied by beer in an estimate of a European medieval monastery.