"Life in the Fat Lane," an NBC News "Report on America" at 10 tonight on Channel 4, belongs to the lean cuisine line of network documentaries. It's video lite, at times resembling a glorified edition of "P.M. Magazine." Fact is, though, it's also consistently and infotainingly engaging.

It's everything you didn't particularly want to hear about weight loss because you knew in your heart it was all too true. "There is no common cause for overweight," says anchor Connie Chung, "and, so, no common cure." The only solution, she keeps repeating, is to "eat less, exercise more, and do it forever."

True, this is the stuff of You News, a USA Today of the air, and not an earthshaker on the Persian Gulf. But many is the viewer who will hang on every word. And on every fleeting picture, too.

Oprah Winfrey (at her most ingratiating and self-effacing), Dom DeLuise, comic Roseanne Barr, Nell Carter, Tommy Lasorda and other celebrities known for their weight problems talk about the tortures of dieting, and Jane Fonda, known for her ideal and much publicized figure magnifique, says she converted to aerobicism after suffering anorexia and bulimia in her inge'nue days.

The documentary isn't exactly organized; its ingredients tend to whirl around in a Cuisinart. But there's something interesting every single minute, especially if one is among the millions constantly doing battle with certain immutable laws of physical science. Diets make you fat, as Chung reports, and quack solutions have little long-term effect. Of those who go on diets, 95 percent put the weight back on -- and often, more besides.

Creepy new techniques like lyposuction -- siphoning fat away with a hose -- are discussed (with excessive, revolting close-ups of the process being performed), reasons for fatness are examined, and such peripheral topics as discrimination against fatties are looked into, if superficially.

The United States is "the fattest nation on earth," says Chung, and getting fatter. One reason, not given enough attention here, is television, with its perpetual parade of skinny models and equally perpetual pitches for worthless, harmful, fatty and sugary foods. On the other hand, rats get fat and, unless they're putting something over on the laboratory technicians who study them, they never watch TV. Not even cable.

Chung and cowriter Sid Feders, along with executive producer Paul W. Greenberg, maintain a respectable balance between laughing-it-off ("I cannot beat the linguine habit," laments Lasorda) and getting justifiably serious. The program has a tacky visual appearance, but it's completely absorbing anyway.

For once, there is no prefatory appearance by NBC News' living logo Tom Brokaw at the top of the show. Anchorboy has been out on the coast doing a dog and pony show for NBC affiliates. Chung does just fine on her own.

'There Were Times' Achingly well-intentioned, but tidily predictable down to the last sniffle, "There Were Times, Dear," a PBS one-hour drama at 10 tonight on channels 26 and 32, adds little to the accumulating television literature on Alzheimer's disease, and does so awkwardly, besides.

Shirley Jones plays a loving wife whose loving husband, Len Cariou, part owner of a sporting goods store, begins to show preliminary symptoms early in the film.

He is absent-minded and testy and forgets such basic data as how to get home from the ice cream parlor with his granddaughter. When he takes scouts on a camping trip, we know he will get lost in the woods, and he does.

The film opens with an embarrassing groan. Writer Harry Cauley and director Nancy Malone choose the Hollywood way of establishing that this long-married pair still dote on one another; they have them gleefully raving about each other's sexual performance in bed the night before, then romping off for a coy conjugal shower. Yeah, that's true love all right.

Proceeding abruptly from the onset of the disease to "a year after diagnosis," then "a few years later," then "several years later," the film lacks a cohesive credibility. Here and there it does proffer a deft detail, as when the husband announces he is going to the hardware store and the wife, thoughtfully, slips a note into his jacket pocket with his name and address written on it, should he become disoriented and lost again.

Jones makes the most of these moments, but Cariou seems a disease-movie caricature. It would have been far more challenging to the dramatist and to the audience to limit the time frame to the later stages of the disease, and with dialogue and actions impart the basis of love in the marriage that would hold it together even when one partner had all but lost his identity.

The title comes from the song "You Made Me Love You": " ... but there were times, dear, you made me feel so sad." Jones and Cariou waltz to it at the fade-out.

It's touching, but never does the film approach the seriousness or impact of "Do You Remember Love?", the film Joanne Woodward did for CBS on the same subject. One does remember "Love" and one will likely not recall "Times."