(Teachings from Gita) The following was said with regards to excelling the art of Dhyanyoga but I think it's true for excelling in life.
Neither eat too much nor eat too less. If you eat beyond what you can digest then not only will you feel sleepy and lazy, you will also be vulnerable to various kinds of diseases. On the other hand, eating too less or too much fasting is also not good as it adversely affects your mind, body and senses. Thus hampering your ability to meditate.
Neither sleep too much nor sleep too less. You must have an optimal sleep which would relieve you of your exhaustion and make you fresh. If you sleep too much, even after waking up you'll feel sleepy and lazy. However, less than required sleep will leave you tired and fatigued leading to reduced productivity.
So the guide to healthy living is to eat right and sleep right. Once again the teachings reflect the importance of discipline in one's life and what a significant role it plays in your success.