Teenagers on average are spending $2,600 annually on food and clothes, favoring retailers Lululemon, Ulta, Amazon and Vans, along with fast-food chains like Chick-fil-A and Chipotle, according to a new survey.

Piper Jaffray asked 8,000 teens, with the average age 16, across the U.S. where they were spending money; 54% of respondents were male and 46% were female.

The study comes as the retail industry is trying to figure out the shopping behavior of teens, who are often referred to as Gen Z consumers, born between 1997 and 2012. Piper Jaffray has estimated teenagers accounted for more than $75 billion in spending power at the end of last year, with roughly a quarter of the U.S. population under 20 years old. As this budding group of consumers opens up its wallet even wider, it's an important one for retailers to target if they want to stay ahead and keep growing.

In addition to uncovering teens' top shopping destinations, Piper Jaffray found 83% of teens have an iPhone, meaning many of them are shopping straight from a mobile device. Males are spending more money on food, while females are spending on clothing. And half the group said Amazon, not Walmart, Macy's or Target, was their favorite website for shopping.

On Piper Jaffray's survey this year, Lululemon is listed as one of the top 10 apparel brands among teens (coming in at No. 8) for the first time. The leggings maker also surpassed Adidas to become the No. 2 preferred athletic apparel brand, behind Nike.

Ulta overtook LVMH-owned Sephora to become the No. 1 destination for beauty, while e-commerce make-up brand Glossier cracked the list at No. 10.

Overall, the favorite apparel brand among teens remains Nike, followed by American Eagle, Adidas, Forever 21, Hollister, PacSun, Urban Outfitters, Lululemon, Victoria's Secret and H&M.

For shoes, VF Corp.-owned Vans took the most market share, or 20 percent, that Piper Jaffray said it's ever recorded for the brand, which puts it still second to Nike with 41 percent of teens saying Nike is their favorite retailer to shop for sneakers.

Among what Piper Jaffray describes as "upper-income teens," the top brands no longer being worn this spring include Under Armour, Gap, Justice and Aeropostale.

"Gen Z is the first digitally native demographic cohort — practically born with a phone in their hand," Piper Jaffray analyst Erinn Murphy said. "Gen Z actually cares [about social and political causes]. ... This could be a powerful generation."