Bhagavad Gita Chapter 6, Verse 16

नात्यश्नतस्तु योगोऽस्ति न चैकान्तमनश्नतः | न चातिस्वप्नशीलस्य जाग्रतो नैव चार्जुन ||

nātyaśnatas tu yogo 'sti na caikāntam anaśnataḥ na cāti-svapna-śīlasya jāgrato naiva cārjuna

O Arjuna, there is no possibility of one's becoming a yogi if one eats too much or eats too little, sleeps too much or does not sleep enough.

Krishna explains that yoga requires moderation in lifestyle. 'Nātyaśnatas tu yogo 'sti'—there is no yoga (yogaḥ) for one who eats too much (atyśnataḥ). This means: overeating makes you sluggish, heavy, unable to meditate. 'Na caikāntam anaśnataḥ'—and (ca) not (na) for one who does not eat (anaśnataḥ) exclusively (ekāntam). This means: not eating at all, or eating too little, makes you weak, unable to sustain practice. 'Na cāti-svapna-śīlasya'—and (ca) not (na) for one who sleeps too much (ati-svapna-śīlasya). This means: excessive sleep makes you lazy, dull, unable to be alert. 'Jāgrato naiva cārjuna'—and (ca) not (na) for one who does not sleep (jāgrataḥ), O Arjuna (arjuna). This means: not sleeping enough makes you exhausted, unable to focus. Yoga requires balance—moderate eating, moderate sleep. Neither extreme works—too much or too little of either prevents yoga.