As an increasing number of Americans see it, our overfed physiques and gargantuan SUVs aren’t the only things that could use some slimming down -- the ballooning American home needs to go on a diet, too.

Consider the evidence: The average American home grew from 983 square feet in 1950 to 2,349 square feet in 2004 -- a 140% increase. Yet the American household shrank by 18% between 1970 and 2003, from 3.14 people to 2.57, on average.

But does square footage equal happiness?

In recent years, a less-is-more upswell has begun, stoked largely by architect Sarah Susanka’s best seller, “The Not So Big House,” and related books. Susanka and her cohorts’ message is simple: Smaller can be beautiful, and better.

Trashing the big = success model
“There are always going to be people who want the big house, even if they don’t need or even use all of that space, and the reason is that a part of our culture associates bigness with success -- a big car, a big house,” says Michelle Kodis, author of “Blueprint Small” and other books. But, Kodis adds, “There is a whole other group of people, which is quite significant, who want just enough space, who don’t want to be showy, who don’t need 10,000 square feet to show that they’ve made it in America.”

What's your home worth?

Susanka has zeroed in on this group even further. “It’s at least a quarter of the population of the United States (referring to what author Paul Ray calls the “cultural creatives”) who look at what’s happening in suburbia and say, ‘Oh my God, I don’t want that.’ They have historically purchased existing houses in the inner ring of the suburbs. The reason they’ve done that is that the houses have character and the neighborhoods historically are strong.” These people are often educated, progressive types of varying income levels who think about more than just their own needs. “You could say they have ‘green’ values,” Susanka says, speaking from her not-so-big home office in Raleigh, N.C.

The trend toward smaller, more finely outfitted domiciles is particularly obvious in urban areas right now, argues Richard Gollis, principal at The Concord Group, a Newport Beach, Calif.-based real estate research firm. That’s because cities are home to the “urban barbell” -- older people without children, and young professionals without children, who want to enjoy the vibrancy of a city.

“We’re starting to see that buyers are willing to trade off size, square footage, for location,” says Gollis.

Small as radical
Susanka’s idea was so simple it was radical: “It’s time for a different kind of house,” the architect wrote, manifesto-like, in her 1998 book “The Not So Big House.” “A house that is more than square footage; a house that is Not So Big, where each room is used every day. A house with a floorplan inspired by our informal lifestyle instead of the way our grandparents lived.” She derided most spraddling suburban tract homes, with their unused dining rooms and their too many bathrooms, as spacious but not particularly comfortable -- less nests than “massive storage containers for people.”

That book, and the five that have followed, clearly tapped into something. More than 1 million of Susanka’s books have been sold since 1998, including the latest, “Outside the Not So Big House: Creating the Landscape of Home,” which just appeared. A bevy of books by other writers in recent years have struck a similar theme.

How much room does a couple or a family really need, anyway?

“As long as you use all of the space actively, that’s the amount of room you need,” says author Kodis. “The goal of smaller-space living is not to cram yourself into a smaller space to make a point.” Instead, in such a home, “There’s no wasted space, but it’s comfortable.” For example, how many families honestly use their formal dining rooms or living rooms -- a few times a year? Then why pay for homes with them, and pay to furnish them? Wouldn’t it be better, Susanka and others ask, to focus on creating a very well-suited kitchen/dining/living area, since most families spend their time there?