The spelling of the phrase "eat cat food" can be explained using the International Phonetic Alphabet (IPA). The word "eat" is spelled /iːt/ in IPA, with a long vowel sound represented by the letter "i". The word "cat" is spelled /kæt/ in IPA, with a short "a" sound represented by the letter "æ". Finally, the word "food" is spelled /fuːd/ in IPA, with a long "oo" sound represented by the letters "uː". Therefore, the complete spelling of "eat cat food" in IPA is /iːt kæt fuːd/.