According to ZnewsKoo shared the habit when he reunited with Hong Kong actress Jessica Hsuan after 25 years at a promotional event for their latest film, “Back to the Past,” on Jan. 9.

“Giving up sweets was harder than I expected,” he said.

Koo also addressed recent concerns about his health, reassuring fans that he had only suffered a mild cold. He was hospitalized on Jan. 2 as a precaution but resumed work the following day, he said.

The 56-year-old actor first rose to prominence in TVB dramas such as “The Condor Heroes,” “Detective Investigation Files IV” and “A Step into the Past,” building a loyal fan base across Asia before shifting his focus primarily to films.

“Back to the Past” grossed HK$10.91 million (US$1.4 million) on its opening day on Dec. 31, 2025, setting a record for the highest first-day performance by a local film and ranking second on the all-time opening-day box office list behind “Avengers: Endgame,” the South China Morning Post reported.

The film is based on the 2001 TVB drama series “A Step into the Past,” featuring largely the same cast.