Thanks for the reminder, but rather than an oxygen diet it constitutes a dietary supplement, the evidence is that no or very few people in history have been able to live on an oxygen diet. The great masters did not practice that diet.
Perhaps you are right, because it has been mainly saints, not Masters that never ate. So maybe it was intended to be a dietary supplement. Who knows what the highest Satya Yuga will bring to humankind in attainment. Certainly not I. Anyhow, I think there are more important things to consider in our spiritual development.
I think that's the food for a very distant future, maybe the next Satya Yuga. I wish I were wrong though.
Sun Rays in Lesson No.19 The future food of man will be various rays of cosmic energy . Cosmic rays, electrons, atoms, and air will be drawn in through different openings of the body. If one constantly keeps his mind concentrated upon the point between the eyebrows (at the Kutastha center) and sees there the spiritual eye and commands it to recharge the body with strength, it will do so, If this were practiced, we would cease to grow old. Energy may be drawn from the sun by covering the whole body with a piece of thick blue silk or a blanket and keeping the medulla oblongata exposed to the sun. Concentrate upon the back of the head and feel it getting warmer and warmer. Feel the energy being stored in the brain and distributed through the body. Take a sunbath and concentrate deeply upon the sunbathed surface of the body, drinking the sunshine in through every pore. Concentration upon the sunrays gives one hundred times greater results than taking a sun- bath absentmindedly.
Sit upright in a chair. Close your eyes. Expel the breath quickly, but start inhaling very slowly through the nostrils, thinking that your brain, lungs, heart, spine, stomach, abdomen, thighs, legs, arms, and so forth, are being filled with air. You can also inhale quickly and fill the whole body with the atomic power in oxygen.
~ Paramahansa Yogananda