Our bodies are made from the foods we eat. So, the food we eat has an effect on the body, the body affects the mind, and the mind in turn influences the body. It is very important that we feed ourselves the best foods to improve the health. This has been practiced and known in India for thousands of years. The great masters and sages have developed health guidelines to assist yogis in their study and practice of yoga.
Yoga philosophy shows us how we are influenced by three qualities (gunas): tamas (negativity and laziness), rajas (energy and preservation), and sattva (purity, calmness, and peace). All foods fall into one of the gunas. Negative (tamasic) foods are: beef/pork, alcohol and processed foods. Energizing (rajasic) foods are: hot, spicy, bitter, sour and pungent. Purifying, peaceful (sattvic) foods are: fresh fruits and vegetables, natural sweeteners like honey and agave, whole grains, legumes, and nuts.
If you avoid negative foods, primarily eat from the purifying foods, and partake sparingly of the energizing foods, you will experience peacefulness, happiness and health in your body and your mind. Your practice of yoga asanas (poses) will become much easier, flexibility will grow, strength will develop, your mood will improve and your habitual thoughts will become more uplifting.
Your yoga practice will benefit from these healthier choices, allowing ease and flexibility in your asanas (postures).