WE has become the network for emotional ambush. Both “The Locator” (8 p.m. today) and “I Want to Save Your Life” (9 p.m. today) involve minor celebrities armed with a camera crew bursting into somebody’s private life with the intention of turning it upside down.

Charles Stuart Platkin, host of “I Want to Save Your Life,” calls himself a diet detective, but it’s creepier than that. By his own admission, he stalks people and observes their eating and exercise habits and then teams up with a loved one to challenge his subjects to change their ways. It’s a strange combination of “Intervention,” “Biggest Loser” “This is Your Life” and a visit from Jacob Marley’s ghost.

In tonight’s pilot, Platkin startles Jennifer mid-bite in a family restaurant. She’s a mother of three with terrible eating habits, a non-existent workout schedule and self-esteem issues that have much to do with the fact that she’s carrying at least an extra 125 pounds around with her. Platkin spends a week with her, organizing her cupboards, her closets and her life and then promises to return four weeks later to see if she’s kept on the straight and narrow.

I’m not giving away too much to reveal that Jennifer emerges more fit and confident, if not exactly svelte. But you have to wonder about the audience for such fare. It’s one thing for Discovery to cater to a viewership of armchair crab fishermen with shows like “Deadliest Catch.” It’s quite another to encourage people to go on vicarious diets from the safe distance of a recliner, not far from a humming refrigerator.

• For those keeping count, singer/actress/director Barbra Streisand (born April 24, 1942) turned 67 yesterday. “Streisand: Live in Concert” (7 p.m. today, CBS) presents highlights from a 2006 performance in Florida. Fans of vintage Streisand may prefer the 1968 musical “Funny Girl” (7 p.m. today, TCM).

• She’s cute, innocent, defenseless and 40,000 years old. “Waking the Baby Mammoth” (8 p.m. Sunday, National Geographic) documents the discovery of the perfectly intact body of a 4-month-old mammal who perished in the late Pleistocene Era. Preserved in frozen Siberian tundra, the cadaver offers a window on a long extinct species as well as the hardy residents of present-day Siberia. Complete with many scenes of laboratory experimentation and scientific speculation, “Baby” features computer-generated animation depicting mammoths in their natural habitat, back, as they say, in the day.

Today’s highlights

• Daniel Radcliffe stars in the 2002 adaptation of “Harry Potter and the Chamber of Secrets” (7 p.m., ABC).

• Scheduled on “48 Hours Mystery” (9 p.m., CBS): A missing teen may have been a serial killer’s prey.

• Chris Addison and Sinead O Connor appear on “Graham Norton Show” (9 p.m., BBC America).

Sunday’s highlights

• “Dateline” (6 p.m., NBC) rewards viewers with surprise windfalls.

• “Little Dorrit” concludes on “Masterpiece” (8 p.m., PBS, check local listings).

• A careful plan unravels on “The Unit” (9 p.m., CBS).

• An accident proves illuminating on “Brothers & Sisters” (9 p.m., ABC).

• Walt and Jesse confide in dubious counsel on “Breaking Bad” (9 p.m., AMC).