to one's heart's content (eating/drinking)
Colloquial adverb used when eating or drinking as much as one wants, often to the point of being full. Typically used with verbs like 食べる or 飲む.
Yesterday I ate grilled meat to my heart's content.
I drank beer to my heart's content and felt good.
Usually written in kana; the kanji form 鱈腹 is ateji and rarely used.
Ateji (phonetic) kanji form; rarely used and may not be recognized by all readers.
The origin is uncertain. The kanji 鱈腹 is ateji, using 鱈 (cod) and 腹 (belly) phonetically, possibly from the image of a cod's full belly. The reading たらふく may be related to 足る (たる, 'to be sufficient') and 腹 (はら, 'belly'), but this is speculative.