“Regarding Yama and Niyama, these days, he believes, they have no validity except for two of them.
First, what is called Satya Niyama, or what to speak, what not to speak, to whom to speak, how to write, what not to write. These are Satya Niyama.
Another Niyama that should be followed is Āhāra Niyama. That is, how much to eat and what to eat, according to age, profession, etc. You see, the ancient people believed that a young boy could eat as much as he liked. But a Saṃnyāsi should only eat eight handfuls of rice, no more, per day.”
– TKV Desikachar from lectures on ‘The Yoga of T Krishnamacharya’, given at Zinal, Switzerland 1981.

Question to TKV Desikachar on Yama and Niyama:
“The idea behind Yama and Niyama is the attitude we have to the inside and outside.
If I don’t know what is true there is no question of telling the truth.
However there is the intention, because one day it may become a reality.
Even though some of these things are not there in the beginning, if the intention is sincere then one day it will become an action if conditions and our psychological state change.
Yama as telling the truth also means discretion.”
– TKV Desikachar France 1983