CC Madhya 3.80

āji upavāsa haila ācārya-nimantraṇe
ardha-peṭa nā bharibe ei grāseka anne
Word for word: 
āji — today also; upavāsa — fasting; haila — there was; ācārya-nimantraṇe — by the invitation of Advaita Ācārya; ardha-peṭa — half My belly; — not; bharibe — will fill; ei — this; grāseka anne — one morsel of food.
Translation: 
Although Śrī Caitanya Mahāprabhu was thinking that the quantity of food was enormous, Nityānanda Prabhu, on the contrary, thought it not even a morsel. He had been fasting for three days and had greatly hoped to break fast on that day. Indeed, He said, “Although I am invited to eat by Advaita Ācārya, today also is a fast. So small a quantity of food will not fill even half My belly.”