Andy Lau and Sammi Cheng team up again in "Love on a Diet," the latest film from Johnnie To and Wai Ka-Fai. Lau and Cheng don fat suits to get into their characters for this movie. Directors and producers, To and Wai are fishing in the deep waters of situation comedies that has proven to be profitable for the duo. As such, this is a modest film that is a fun way to be entertained. The fat suits work, for the most part, but act as a mild distraction, particularly with the latex hands that look awkward on camera. But, since this is a comedy, most will forgive the cosmetic make-up effects and suspend their disbelief. The fat premise could have been some other artificial impediment, but that's the choice the filmmakers made.

Andy Lau shines, while Cheng still whines. The whining seems to be her calling card, from "Needing You" to "Wu Yen." "Love on a Diet" is a more engaging film than "Wu Yen," which I thought was dreadful. In this flick, To has Lau and Cheng revisit the formula that made "Needing You" a success. Lau helps Cheng to lose weight so that she can meet her old boyfriend, a musician, using a plot device from Leo McCarey's 1939 film "Love Affair," where the two will reunite under a particular tower in Japan at a future date.

If we overlook the impossible task that Cheng has committed to (losing 200 pounds within six months), we can have some fun watching Lau and Cheng do their best in creating caricatured fat people. One of the funnier moments is when Lau works with his buddies to come up with ways for Cheng to lose weight, from tapeworms to special potions. Lau helps Cheng financially by working as a street-performing, human punching bag. Of course, she doesn't know how he provides for her needs until after she meets up with her old boyfriend.

Recently, To and Wai seem to be creating films that feel small. Nothing about this film makes it urgent, more like composing for television. Almost as if To and Wai were taking a vacation from serious cinema. The assembly line production techniques have taken their toll. The direction was very pedestrian.

"Love on a Diet" is not a laugh out loud riot, but an amusing, warm-hearted look at a two people who come together under odd circumstances and find that they share more in common then they originally thought.