In the section on niyama there is a word called tapas.

Tapas here includes ahara niyama - right food but in limited quantity. So, niyama which is a personal discipline includes regulation of food habits. In other texts like Hatha Yoga Pradipika, before the author talks about pranayama, proper food habits are insisted upon. Today it has become essential to suggest some sort of a diet discipline to help those who come for help.

Further, food is also connected to the mind In Chandogya Upanisad it is stated that food influences the mind "Annamayam hi soumya manah"

Without food there is no progress in yoga. That is why my father said four things are essential for success.

• Satvika aharam - food which is sattvic in character
• Satvika sadanam - good actions
• Satvika vidya - learning which is sattvic
• Satvika sangam - to be in sattvic company

Whenever I was sick my father used to say, "you have been careless with your food. That is why you are sick". He always thought a person was sick because of carelessness in food. Ayurveda also talks about food - "Aharam, Viharam, Ausadi. ie. Food, lifestyle and medicine as the three means to treat the sick.