Once on the spiritual path, you will get a calling from within to watch what foods you put into your body and how you keep your body clean and healthy. This, namely saucha or purity, as Yogani explains in his book, belongs to the Niyama limb, one of the eight limbs of yoga from the sutras of Patanjali.
Yogani has done an excellent job in covering various factors of diet, and explains why most "fad diets" fail. The concept that one diet plan will fit all is not practical and it is important to listen to your body when you decide to improve your diet. He covers what kinds of foods to eat, how much to eat, and ways to cook food. He explains the foods that help balance the Ayurveda doshas - vata, pitta, kapha. He also covers fasting, addictions, drugs and yoga, and talks about the relation between kundalini (specifically the inner processes of soma, amrita and ojas), digestion and diet .
In Shatkarmas he covers cleansing techniques for mouth, nasal passages and sinuses (various forms of "neti"), colon ("bhasti"), intestinal wash ("dhauti"), nauli ("churning" of the abdominal muscles), kapalbhati ("shining face" technique) and trataka ("steady gazing").
This book also covers detailed instructions for Amaroli (urine therapy) and explains the many applications and benefits this practice has in health and spirituality.
He finally puts all of the techniques together and describes how all of this, when done along with meditation and pranayama, will help us progress on our spiritual path, increasing our inner silence, happiness and creativity in all we do in life.
This book helped me understand how to listen to my body for cues on what kind of foods I should eat to pacify the various dosha flare ups that I seem to go through on my spiritual path. Light and nutritious diet along with eating smaller quantities do help a lot. This book also helped me understand the changes occurring in me with respect to soma and amrita. I have added the neti, nauli, kapalbhati and trakata to my yoga practices and they do help with the movement of inner energies and seem to enhance my practice by a lot.
I would highly recommend this book to anyone looking for one place to find all the information required for yogic diet and cleansing in one book. Really awesome book.