It seems that some ancient Chinese had it all figured out when it came to grains. Bìgǔ (avoidance of grains) was a fasting technique practiced by Daoists during times of political turmoil when many fled to mountainous areas to live a more peaceful existence but were initially unable to raise livestock or grow crops and were forced to forage to survive.
They found that the grain-free diet that had been imposed on them reduced their risk of contracting illness from parasites and bacteria. They eventually grew to believe that avoiding grains led to “xian” or immortality.
I have personally observed for two or three years, men, who were foregoing starches, and in general their bodies were slight and their complexions good. They could withstand wind, cold, heat, or dampness, but there was not a fat one among them.
Ge Hong – 320 AD From his book Baopuzi (Master Who Embraces Simplicity)