Facebook is adding customizable interest-based feeds. A newspaper made up of all the world's newspapers. pic.twitter.com/Ll7pib6Mb5

— Jason Stein (@jasonwstein) December 29, 2015

Facebook CEO Mark Zuckerberg has said that he wants the social network's news feed to be "the best personalized newspaper." But newspapers have sections, and now so does Facebook's news feed, at least for some people.

The social network has been experimenting with category-specific versions of its news feed that take posts that would normally appear in the all-in-one feed and organize them into their own interest-specific feeds. It began the test in October, as reported by Social Times, and now appears to be extending it to mobile.

On Tuesday Laundry Service CEO Jason Stein tweeted a photo of the interest-specific feeds as they appeared in Facebook's iPhone app. The photo shows the regular Facebook news feed as well as tabs for "travel," "style" and "headlines" feeds.

"People have told us they'd like new options to see and have conversations about more stories on Facebook around specific topics they're interested in," a Facebook spokeswoman said in an email. "So we are testing feeds for people to view different stories from people and Pages based on topic areas. You can access these feeds from your Bookmarks, located underneath Favorites, or a navigation bar under Search."

In Mr. Stein's example, Facebook offered 13 interest-specific feeds that pull in posts from the friends and pages someone follows as well as posts from accounts that person doesn't directly follow, such as publications whose stories appear in the "headlines" feed, Mr. Stein said in an email.

People can also customize these feeds. In a screenshot Mr. Stein provided that shows how customization works for the "style" feed, Facebook offers sub-categories such as women's fashion and beauty tips, plus the option to search for other sub-categories.

No ads appeared in the interest-specific feeds Mr. Stein encountered, which will probably change if Facebook ends up rolling the feeds out to all of its users.

Mr. Stein boiled down Facebook's motivation for interest-specific feeds: "More feeds, more personalized experience, more time spent in app, more [ad] inventory," he said.

The test appears to be the latest example of Facebook trying out ways to relieve the flood of content pressuring the news feed. As more people join Facebook to keep up with their friends, celebrities, sports teams, publishers, brands and so on, and as more of those people post more content, it has gotten harder for Facebook to figure out which of that content to show someone. Should the first post in the feed be a friend's phot of their new baby from last week, a breaking news story or a funny video that's been making the rounds?

Facebook's news feed algorithm is supposed to answer that question, but Facebook has been adding ways to give people more control over the answer. Last year it began letting users turn down the frequency of posts they see from the people most often in their news feeds. It added a "trending" section to show the most popular topics of the moment. And earlier this year it added a way for people to tell Facebook whose posts they want to see first, whether it be a friend or a brand.

But Facebook's interest-specific feeds aren't really all that new in concept. Facebook previously tried a version of interest-specific feeds in Paper, mobile app that ingests users' news feeds and divvies them up into newspaper-like sections, such as sports, news and entertainment.