We all know what happens when we overload our plate at big family holiday meals.

Our eyes are bigger than our stomachs, the tasty starches take precedence and we rationalize all those samples of extra sugary desserts we squeeze in around the edges.

And before we’re a third of the way into digging in, it all swirls into a treacly glop, not quite inedible, not remotely healthy.

The same holds true for big “family” holiday comedies. Overdo it and the glop takes over.

“Love the Coopers” is “This Christmas” and “The Family Stone” and their many inferior clones, all rolled up into one tasteless lump.

“Coopers” packs three Oscar winners, and a lot of talent that might make an acceptance speech someday, into a misshapen mess so cliched and cloying and sweet it’ll make your teeth ache.

There’s the narrator (Steve Martin), opening with, “Ah, the holidays.”

Seriously?

And then there’s long-married couple (Diane Keaton, John Goodman) throwing the big dinner, “one last chance to feel like a family before we tell them” they’re splitting up.

Ed Helm is the lonely, unemployed and divorced father of three who can’t land a job and can’t keep his own secret — that he can’t find work — much longer.

Marisa Tomei is Keaton’s character’s younger sister, who so resents her that she shoplifts a tacky Christmas present. Anthony Mackie is the “robotic” and over-groomed cop who arrests her and takes the entire movie to get from the mall to the jail. In Pittsburgh.

We see the troubled oldest granddaughter (Olivia Wilde) meeting Mr. Nice-But-Not-Compatible in an airport bar, and conning him into playing her “date” with the parents. She’s a failing atheist playwright having an affair with a married man, he’s a Creationist-conservative soldier (Jake Lacy) headed home before deploying overseas.

Her biggest fear? “Anticippointment,” the waiting for Mom and Dad’s first look of disapproval. His duty? Lie about being her beau. “It’s the Christian thing to do!”

Alan Arkin’s the patriarch with a crush on a waitress (Amanda Seyfried) less than half his age, and June Squibb is the slightly-demented old aunt they fetch, once a year, for this big dinner.

“Be sure to take the Internet. It’s faster!”

There’s a lovelorn teen in search of his first kiss, a family sing-along (Helm on guitar, Goodman on harmonica, Keaton and…a first, Arkin, singing), legions of mall Santas, insistent, incessant snow, a snow-tubing outing and endless cutaways to the cute, ill-mannered dog.

Yeah, there are moments that play and big laughs that land, here and there. Wilde comes off the best. Somebody should write her a “Too Beautiful and Too Mean to Date” farce. Soon.

But it’s all so hackneyed, so overfamiliar and formulaic.

The formula should work, but when you can guess a character’s story by the way he looks and the fact he’s named “Percy,” you know you’re dealing with a director (He wrote “Because I Said So,” a low-point in Keaton’s career) and screenwriter  (“Kate & Leopold”) who haven’t observed real people for their “observational” monologues in this century.

There’s always room for a movie like this during the holidays, one that’s safe to take granny and the grandkids to. But “Love the Coopers” will make one and all wonder why they bothered to get up from the table and paid multiplex prices for a movie they’ve seen, many times, before.

MPAA Rating:PG – 13 for thematic elements, language and some sexuality

Cast: Diane Keaton, John Goodman, Olivia Wilde, Marisa Tomei, Alan Arkin, Amanda Seyfried, Ed Helm, Jake Lacy
Credits: Directed by Jessie Nelson, script by Steven Rogers. A Lionsgate release.

Running time: 1:50