Morgan Spurlock, whose "Super Size Me" -- the 2004 film record of his month-long experience on a McDonald's-only diet -- attracted sizable audiences, as documentary films go, and won its creator an Oscar nomination, delivers another kind of diary record in "30 Days" (Wednesdays on FX, 10-11 p.m., EDT).

Some of it promises, if briefly -- very briefly -- to offer investigative journalism with a touch of nuance, as in next Wednesday's episode on the scandal of anti-aging treatments: the kind of subject long dear to the hearts of magazine-show reporters.

The series is built around the daily recorded adventures of people Mr. Spurlock assigns to live lives wholly different from their own for a period of 30 days. So here's Scott, of Los Angeles, a formerly trim 35-year-old door-to-door salesman. He's happily married with children, but unhappy with his accumulating girth, mid-afternoon fatigue and overall sense that he's no longer the hunk he was, and he hasn't exercised for decades. Accordingly, Scott enters an anti-aging program that will require him not only to exercise, but to take growth hormones, testosterone injections and huge amounts of nutritional supplements -- from which information alone it will be clear that he's embarked on a dubious battle.

If the drugs aren't enough, there's the doctor in charge of the therapy, an assured if somewhat disheveled authority who informs Scott that he has been on the same anti-aging regimen himself for years -- not the highest recommendation, to the naked eye.

In addition to all that, there's the filmmaker, a Greek chorus of one who shows up between scenes to deliver little prosecutorial summaries. The episode offers his indictment, early on, of the extraordinary degree of vanity to which Americans are prone, of their quest for youth, of the people who undergo cosmetic surgery, inject themselves with Botox and, of course, seek the kind of anti-aging treatment Scott has signed up for.

In short there are to be no surprises here. The 30-day experiment can only end, like all such television investigations, one way -- with frauds and charlatans unmasked, their victims left to mourn their losses. Still, it's evident that Mr. Spurlock was after something more with his diary, something on the order of real drama, of which we get hints -- here are the nuanced parts -- about the growing tensions in Scott's household.

Troubles soon pile up -- Scott's liver readings become abnormal after he takes the prescribed massive doses of supplements, along with the growth hormones and steroids. That's in addition to the threats to his sperm count. There's something decidedly natural and plausible about those tensions, played out though they are before a filmmaker's camera. The anger Scott's wife feels when things begin going wrong is entirely evident in the hooded looks she gives her husband -- a sight to chill the blood. A pity Mr. Spurlock didn't allow his subjects to tell the story he assigned them, instead of interrupting with informational vignettes starring his very own self -- like the one where he goes off to Mexico to bring back the not-very-hot news that you can buy all sorts of medications and other controlled substances there, without a doctor's prescription.

In the following episode (June 29), Mr. Spurlock's subject, a deeply religious Christian from Charleston, W.Va., isn't aiming for physical transformation. Dave, age 33, has been assigned to 30 days among Muslims. It's a way of instructing him in their culture and faith, about which Dave is -- and this we can believe -- profoundly ignorant. Also a way, as Mr. Spurlock clearly intends, in which this pilgrim sent into deepest Dearborn, Mich., can advance the view that profiling is an illegitimate tool, that Islam is a peaceful religion, that Muslims have had a hard time because of suspicions directed at them since 9/11, and that -- as Mr. Spurlock goes on to say in one of his own lectures -- America is caught up in an epidemic of "Islamophobia." And unlike Scott's, Dave's is meant to be a success story, thanks to the enlightenment that he has attained, supposedly, after spending a month living with a devout Muslim couple in Dearborn.

In just 30 days, Dave has become so enlightened that he is pronouncing, if incomprehensibly, on the meaning of Islam, his knowledge of the Quran, the real definition of jihad. The segment has its compelling moments, among them a scene in which the imam explains, with charming delicacy, why Dave shouldn't be sitting with the soles of his shoes turned toward another person's face. Dave isn't exceptionally quick to get the point -- yet, he's managed to learn all about the Quran in a month. Miracles happen.

Another Christian traveler seeking enlightenment -- this one self-appointed -- is the subject of "POV'"s "The Education of Shelby Knox" (Tuesday, 10-11 p.m. EDT on PBS; check local listings). Fifteen-year-old Shelby began a high-school crusade for serious sex education in the Lubbock, Texas, public schools -- a no-win battle since Texas law has, since 1995, mandated abstinence-only sex education. Committed herself to an abstinence-only vow, Ms. Knox stubbornly pursued her campaign, inspired, we learn, by the high rate of teen pregnancy and sexually transmitted diseases she saw around her. Young Ms. Knox, who is given to frequent bouts of tears -- as when she lost a class election, other times for reasons more mysterious -- nevertheless manages to develop a certain backbone in the course of her struggles for justice.

The film begins with the memorable quote attributed to singer-songwriter Butch Hancock of the Flatlanders: "Life in Lubbock, Texas, taught me two things. One is that God loves you -- and you're going to burn in hell. The other is that sex is the most awful filthy thing on earth and you should save it for someone you love."

Savor that. There won't be anything else by way of civilizing irony to dilute the profound, grinding earnestness that weighs this work down -- and raises suspicions that documentaries about principled high-schoolers at odds with repressive authority are likely to be exceedingly solemn and focused on heroes given to impressive levels of self-absorption. The last count, of course, can always be dismissed as the natural condition of the young, which doesn't make lengthy exposure to it any easier to take.

CORRECTION: In my June 3 review of HBO's "The Comeback," Michael Patrick King was incorrectly described as the creator of "Sex and the City." He was the executive producer of that show, created by Darren Starr.