Compared to the preceding singles following "Colors", "Flavor of Life" garnered far more success. This single is Utada's first single since 2003 to sell over 200,000 copies in its first week, the first single ever to sell over two million downloads before a physical format release, the first single to sell over five and a half million downloads total, the first single to top RIAJ downloads for three consecutive months, and the first song to be certified platinum for PC downloads in Japan. "Flavor Of Life" has become the highest selling Japanese download single of all time, with over 5,580,000 downloads by April 2007. On July 19, 2007, EMI disclosed "Flavor Of Life" as a contender for most sold digital single of all time, with over 7.7 million downloads total.

There were three versions of the "Flavor Of Life" that were released: "Flavor Of Life", "Flavor Of Life -ballad version-" and "Flavor Of Life -antidote mix-" (a CD-only exclusive). The ballad version of "Flavor Of Life" was arranged by Utada as well as two other professionals; the original version was arranged by Utada, and the antidote mix of the song was arranged by Alexis Smith, who provided additional arrangement for Ultra Blue tracks such as "Keep Tryin'" and "This is Love".

The ballad version of "Flavor Of Life" was featured as the insert song for the popular drama or dorama, "Hana Yori Dango 2," which averaged over 21% viewership in its timeslot. In early 2006, the production team of the drama contacted Utada about an image song that would sound similar to "First Love". When the director wanted to express the heroine's wavering feelings, he said that, "'First Love' came into my mind", and so, a request was made to Utada.

This is Utada Hikaru's first drama tie-in since "Sakura Drops" in 2002. This is also her last physical single to be released under Toshiba EMI, before the British EMI Group purchased its remaining stake in the label from the Japanese Toshiba Corporation and was rebranded as EMI Music Japan.

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