Shadow Karma...
A Sattvic diet is excellent for those individuals who desire to live a quiet, peaceful and meditative life. Sattvic foods comprise the diet of many sages, yogis and spiritual teachers. These foods are supposed to produce calmness and nobility among people.
Unfortunately, the world is clouded and life is fast so people tend to be more rajasic and also tamasic. But one can't impose their beliefs upon others, it does take time and people learn from their mistakes.
One should focus on work, self-improvement and intellectual or spiritual pursuits. Maintaining a positive nature, demonstrating generosity, kindness, openness, fairness (equality) and forgiveness also increases Sattva Guna. In addition spiritual inclination, faith and belief in the Great Spirit or God, engaging in selfless service or charitable activities help to become Sattvic.
It takes time for the effects of dietary changes to manifest on the mind. Changing our diet may not impact our psychology overnight, but in a period of months can affect it significantly.
In Chapter 17 (verses 8, 9, 10), Sri Krishna makes clear the type of foods to be avoided by those who seek good health, worldly success, and progress on the spiritual path.
According to the Bhagavad Gita, foods which are too bitter, sour, salty, pungent, dry, and hot can lead to pain, distress, and disease of the body. Further, Sri Krishna says that foods cooked more than three hours before being eaten, foods which are tasteless, stale, putrid, decomposed and unclean should be avoided by spiritual aspirants and those who seek excellent physical and mental health.
In Chapter 6, verse 16, Sri Krishna specifically emphasizes moderation in eating and sleeping. He states, “There is no possibility of ones’ becoming a yogi, O Arjuna, if one eats too much, or eats too little, sleeps too much or does not sleep enough.”
Clearly, over consumption of food leads to problems and one can logically conclude that the quantity of food consumed is probably an important element in a diet being considered Sattvic.
Sattvic diet is also a matter of degree. Some diets may be very Sattvic, while others may be moderately Sattvic.