Last week on “30 Days” (9 p.m., FX), nearly 2 million viewers watched filmmaker Morgan Spurlock (“Super Size Me”) and his girlfriend, Alexandra Jamieson, spend a month subsisting on minimum wage. Tonight, Spurlock cedes guinea pig status to a former high school swimming champ who has seen his once svelte physique become a tad too pear-shaped.

This 34-year-old married father of two decides to embark on a month-long effort to turn back the clock (and his scale) by engaging in a radical diet and exercise binge, as well as daily injections of steroids and hormones and a fistful of over-the-counter nutritional supplements.

He swallows more than 25 pills a day.

As in the documentary “Super Size Me,” Spurlock’s 30-day experiment of eating only McDonald’s food, tonight’s subject undertakes this challenge under doctors’ supervision. And his doctors are quickly alarmed.

His liver functions go haywire, and his once-healthy sperm count plummets to near zero. This irks his wife, who shoots “I told you so” daggers with her angry eyes. They had been planning on a third child. If we learn anything from this “30 Days” installment, it’s that it’s difficult to be the wife of a man who treats his body like a chemistry set.

Host Spurlock appears in several informative vignettes, traveling south of the border to demonstrate just how easy it is to score illegal steroids in Mexican border towns.

Tonight’s other highlights

¢ Scheduled on “60 Minutes” (7 p.m., CBS): a controversial medical treatment results in death; an emerging kitchen star; pianist Leon Fleischer struggles to regain the use of a damaged hand.

¢ A fatal encounter with an old classmate on “Psychic Detectives” (7 p.m., NBC).

¢ On back-to-back episodes of “Law & Order” (NBC), a parolee becomes the victim of a hit and run (8 p.m.), a murdered tycoon’s bride and her hunky lover become suspects (9 p.m.).

¢ A vigilante targets possible serial killers on “The Inside” (8 p.m., Fox).

¢ A very deep end for a construction worker on “CSI: NY” (9 p.m., CBS).

¢ Locke’s story leaks out as Jack makes a controversial proposal about the non-survivors on “Lost” (9 p.m., ABC).