If you never went out to dinner, and didn’t pay for cable TV, and you and your spouse cut each other’s hair instead of going to salons, and everything you owned you bartered for or bought used on Craigslist; and if you drove really old cars, and you quit going to Dunkin’ Donuts with your best friend because one measly glass of iced tea costs $2.50, well, then, maybe you, too, could retire in your 30s.

That is the premise — laid forth with frequent caveats about how privileged the author is by birth, race, etc. — of “Meet the Frugalwoods,” a chatty, confessional how-to book by Elizabeth Willard Thames, co-founder of the inspirational website frugalwoods.com.

Thames and her husband, Nate, and their two daughters live somewhere in Vermont near a smallish town with good schools and excellent broadband but out in the country on a nice piece of land with lots of trees. This is the sort of vagueness that abounds in this book, which is heavy on inspiration but light on specifics.

Essentially, her message is: Save as much money as you possibly can, and eventually you will be rich. But she’s a little twitchy when it comes to giving us hard numbers. How rich is she? Rich enough to own two homes. How did she get that rich? Hmmm.

Thames spends many, many pages explaining in great detail how she kicked the makeup habit and exactly how much money that saved, and how she finagled free yoga classes. And we learn that right after college she lived on $10,000 a year plus food stamps by living in a terrible apartment in an awful neighborhood and making all of her furniture out of cardboard.

But as the book progresses, the numbers fade away. When it comes to big-ticket items — such as the couple’s four-bedroom house in the heart of Cambridge, Mass. — we’re left to wonder. How did she go from squatting in that wretched apartment to buying that house with granite countertops and hardwood floors in one of the most expensive cities in the country? You don’t get that kind of money by skipping a few haircuts. (Well, to be fair, she had also stopped spending $40 a week on artisanal cheeses.)

We know that she and Nate were, at times, saving 82 percent of their income, but that isn’t very helpful if you don’t know what their income is.

We know that after moving to Vermont they rented out the Cambridge house for income, but for how much? We don’t know. Nor do we know what they paid for the new 2,300-square-foot house on 66 acres of wooded Vermont land.

I am not usually nosy about other people’s money, but if you are going to use your own financial situation as an example, then you need to sacrifice some privacy. Certainly there are plenty of people who don’t have cable TV, don’t get expensive haircuts and don’t splurge on Dunkin’ Donuts who will never be able to buy a second home in Vermont.

Still, to be financially responsible is a worthy goal, and dialing back the consumerism is pretty much always a good idea. For starters, there’s no need to buy this book — save that $22.99! You can borrow it for free from the library. (Thames recommends that very thing on page 100.)

 Laurie Hertzel is the senior editor for books at the Star Tribune. @StribBooks

 Meet the Frugalwoods
By: Elizabeth Willard Thames.
Publisher: Harper Business, 229 pages, $22.99.