• By Robin Kawakami

In a YouTube “shopping haul” video with more than 100,000 views,sccastaneda shares her finds from Forever 21, H&M and Old Navy. Among the bargains: a $22.80 top, a $9.50 skirt and a $6.80 bracelet.

The camera pans to an overflowing closet, and at one point, sccastaneda says offhandedly: “I picked up this tank top, which I put in my cart last night online, and good thing I didn’t purchase it, because I already have it.”

In her new book, “Overdressed: The Shockingly High Cost of Cheap Fashion,”author Elizabeth Cline describes the consequences of our growing fast-fashion habit, starting with the sheer waste resulting from cast-off clothing.

“The figures are just shocking in terms of how much clothing Americans are consuming,” she said in a recent interview. “It’s 20 billion garments a year now.”

And Ms. Cline has bad news for people who take solace in clothing donations: They are buying into the “clothing deficit myth”—the idea that some poor, shivering person out there desperately needs your used garments, when in reality there is simply too much to go around. “It’s a very convenient myth because we can continue to buy clothes and just tell ourselves that someone is going to need them when we cast them off,” she said.

Heard on the Runway talked with the author about her book, due in stores today. Edited excerpts from the interview:

You rail pretty heavily against retailers like H&M, Forever 21 and Zara. Are there any “good” fast fashion chains? I have some items from Uniqlo that I wear all the time that have lasted for years.

Ms. Cline: I think almost the whole mass-market clothing industry is running on the same model, which is churning out an unsustainable volume of clothes. Uniqlo is definitely no exception. They’re a basics company, but the reason they can do what they do is because they produce in such high volume. And I think that that’s what we’ve really seen over the last two decades: consumption skyrocketing. And that’s why these retailers are able to lower their prices. And it quite simply can’t continue. Something’s got to give.

Are there any alternatives you recommend among cheap-fashion stores?

H&M has been doing this “Conscious Collection.” Anytime I see a retailer trying to use recycled or organic materials, I 100% endorse that. I think they should take more responsibility and have some type of drop-off or recycling program for their clothes because it is so disposable and we don’t really use them that often, so I think the consumer should be able to bring those products back to the store for re-use and for future lines.

You argue that luxury handbags are one of the biggest scams in the world. What do you mean by that?

A lot of that section of the book is based on Dana Thomas’s book “Deluxe: How Luxury Lost Its Luster.” This is one thing that blows my mind about the fashion industry: It’s actually really difficult to make a good profit off of clothes, especially well-made clothing. These luxury brands, a lot of them are making quality pieces, and they’re making them in very small numbers, and it’s really really hard to make money off that. So what these companies have done is padded their profits by marking up shoes and pocketbooks.

And I think people fall prey to it because they want to own a piece of the brand, and unlike a dress, it’s suitable to wear the same pair of designer shoes every day, or the same designer bag. And people are just so uneducated about clothes that they’re not able to gauge whether what they’re buying is worth their money or not. I think there are actually are people who think it costs $5,000 to make a handbag.

That’s a big theme of your book: being knowledgeable about quality materials and craftsmanship. What can people do to educate themselves?

There are two things you can do: one is go to a thrift store and look at clothes that were made before the ‘80s. It’s actually not that difficult. You can tell there’s a huge difference in the fabric and sewing used—there are more details.

I also say in the book that one of the reasons why I think people should buy a sewing machine is because it makes you a better consumer. Even if you’re horrible at it, if you have to go to a fabric store and pick out a fabric and try to put something together, it just rewires your brain to think about clothes in terms of how they’re constructed.

Most of your book is about women’s fashion. What role does men’s fashion play?
The men’s industry is pretty different. It’s less fashion sensitive, although the fast-fashion chains are going after the men’s market pretty aggressively now. So menswear is certainly part of all this, and I wish that I had had the opportunity to write about it more.

The retailers know that men aren’t going to go into a store every week and buy something new. They’re still able to buy something that’s a little higher quality, even in a chain store. I’ve seen guys wearing H&M sweaters and I’m like, “Why is that sweater something that would stand the test of time in two years, whereas anything I’d buy from there would fall apart?”

China plays a huge role in today’s fast fashion. One of your chapters talks about rising labor costs there and the end of cheap fashion. Will other countries—like Bangladesh or Vietnam—be able to fill the void?

No. Those places can and do make cheap trendy fashion, but no one will ever be able to replace China in terms of the price point, volume and speed. I went to Bangladesh, and they have power outages six times a day. They’re dealing with the problems of a truly developing country, whereas the parts of China that I went to are completely modernized.

Bangladesh is an underdeveloped country, and it just doesn’t have the population. I think there are maybe 3 million people working in the garment industry in Bangladesh, whereas there are 40 million factory workers in this one province that I went to in China—and they’re not all garment workers, but no one will ever be able to replicate that scale.

So does that mean fast-fashion isn’t going to stay as cheap as it is now?
I think so, and I think that that’s a good thing. And also I think that it will finally give our garment industry a chance to compete. I interviewed a couple of brands in the book that are moving their production back here because the price in China is going up. So maybe that will shift the balance back in our favor.

So what should people wanting to cut back on cheap fashion do? Aside from learning how to sew, you write in the book that vintage clothes are quickly disappearing.
The vintage market is overheated and overpicked now. And I understand why, because there’s a huge contrast in terms of how those clothes are made. And it will eventually dry up. So we’ll either completely forget that good clothes ever existed, or we can all decide now that the industry needs to change and start supporting brands and lines that make things that are better made.

I would say—and this is something your grandmother would tell you: Take care of the things that you own. Buy less. And support local independent designers and retailers when you can. I think that the clothing industry in America was at its best when it was smaller and independently owned. And I would like to see more people returning to that model and supporting that model.