The millennials are the biggest generation the U.S. has ever seen, and the young adult group, defined by demographers as Americans ages 18-37, is quickly exerting its influence on the national economy. As millennials have come of age, so have concepts like fast casual, social media, and athleisure, largely due to the influence of that cohort.

Millennial spending should only continue to grow as young people move further up the economic ladder and form families. For investors, that means that paying attention to millennial-backed trends can yield stocks that will consistently grow over the next 10 or 20 years.

To identify a few of these, we asked five of the Motley Fool's top consumer goods analysts to pick a brand that's formed a lasting connection with the millennial generation. Here's what they had to say:

Jeremy Bowman (Chipotle): With the decline of restaurant chains like McDonald's and Subway, millennials have made their preference for high-quality, natural food clear, and in the burgeoning fast casual space no other company has been a greater beneficiary of this movement than Chipotle Mexican Grill (CMG 0.17%). Chipotle's emphasis on "Food with Integrity," its lack of traditional advertising -- no TV commercials -- and its recent move to eliminate GMOs have all won it favor from the young adult generation skeptical of big food and mainstream marketing.

Chipotle has also emerged as a cultural touchstone, and is often referenced on popular social media accounts. For instance, Elliott Tebele, the creator of the popular Instagram account F*ck Jerry, said in an interview that his most-favorited post was an infant wrapped up like a Chipotle burrito, garnering 150,000 likes. 

Chipotle is well aware of this connection. It holds three "Cultivate" festivals a year at cities around the country, drawing young people with musical acts and food and thereby taking a marketing step the average fast-food chain would never dream of. It also posted the following video on Twitter under the hashtag #AdviceForStudentsThisYear, tapping into its bond with college students.

Millennials love Chipotle and Chipotle loves them right back. It's a symbiotic relationship that should continue to fuel the company's growth and bottom line as it expands nationwide.

Rich Duprey (Nike): There is arguably no brand more closely identified with millennials than footwear and apparel maker Nike (NKE 0.95%), which has transformed itself from simply being a sneaker company -- and a cool one at that -- to a complete lifestyle company that gives its consumer cohort what it most urgently wants: individualization.

Nike gives consumers the chance to be part of the crowd and stand out from it at the same time. Its NikeID site, for example, lets millennials join the cognoscenti by owning a pair of the latest Air Jordans, but lets them express their individuality by customizing the sneaker with colors, materials, and even personal messages. And it makes a handsome profit while doing so, taking in over $30 billion in sales last year and generating $3.3 billion in net earnings.

A lot of companies try to do the same for their customers, but have nowhere near the allegiance. How does Nike do it? By putting the customer first. President and CEO Mark Parker says, "It's our obsession with serving the consumer that sharpens our focus and drives our growth." As their tastes change, so does Nike's product innovation, and that means immersing itself in the sport of choice.

Parker elaborates that "the starting point for innovation remains the same, and that's the athlete. Many of our greatest innovations have come from going deep into an individual sport to solve a unique athletic need." 

So solving problems faced by those who use its products and giving them a platform to express themselves is ultimately the secret to Nike's success, and why it is the choice of millennial consumers everywhere.

Tamara Walsh (Skechers): You don't earn the coveted title of "hottest major footwear brand in the U.S." without first getting the seal of approval from Millennials. This is precisely what Skechers (SKX 0.60%) has done. In just a few short years, the once off-brand shoe maker has transformed into an international powerhouse, with sales climbing more than 36% in its latest quarter . The company recently beat out large brand name shoemakers, including Adidas and New Balance, to take the No. 2 brand share position in the U.S. athletic footwear market.

Skechers stock is up a whopping 175% year-to-date and currently trades at around $152 per share. Moreover, the retailer's success is in large part thanks to its ability to connect with Millennials today. The sneaker retailer is using multimedia endorsement deals with fashionable pop stars and musicians to attract Millennial's to its products. In fact, Skechers recently signed Grammy-nominated singer Meghan Trainor to a two-year endorsement deal that will include global marketing and social media campaigns.

Trainor joins other big names who have backed the brand, including world famous drummer Ringo Starr, recording artist Demi Lovato, and past winners of NBC's The Voice, including 17-year old Danielle Bradbery. These public figures add credibility to the brand, and appeal directly to the 20-something crowd that Skechers is targeting these days. The lower price point of Skechers' kicks compared to that of rivals such as Nike, is yet another reason the company is winning with Millennials today. With Millennials in its court and record sales of $2.4 billion last year, I expect Skechers to continue dominating in the quarters ahead.

Bob Ciura (WFM): Specialty grocer Whole Foods Market (WFM) has not had a good year. Shares are down 35% since just the start of the year.

But for all its challenges, Whole Foods is still popular with Millennials. Last quarter, total revenue increased 8% year over year, and hit $3.6 billion, which was actually a record quarter for Whole Foods in terms of revenue. Earnings per share rose 4% to $0.43 per share, and Whole Foods still generated a 15% return on invested capital last quarter. These are not figures that suggest a deteriorating business.

Whole Foods is capitalizing on the shift in individuals' shopping habits. Consumers, particularly younger consumers like Millennials, are embracing fresher, better-sourced foods like organics. Whole Foods' stock price is declining, but only because its last two quarterly reports missed expectations. I attribute that more to analyst estimates being too aggressive. Whole Foods' underlying business remains sound, and it is still growing at a stable pace.

The near-term may continue to be difficult. Whole Foods management expects only flat earnings per share in the current quarter year over year. But as the year comes to a close, the 365 initiative will begin to kick in, which could be a promising catalyst. The company plans to open up to five of these stores by the end of 2016, and those smaller-format stores could give Whole Foods access to a whole new customer demographic, boosting revenue and earnings growth in upcoming quarters along with it.

And, longer-term, Whole Foods' core focus remains intact. The organics trend isn't going anywhere, and neither is Whole Foods. Younger consumers, particularly Millenials, are increasingly opting for organic produce and healthier foods in general. Whole Foods caters to this demand very well.

Joe Tenebruso (Google): With Millennials set to become the largest generation in the American workforce this year, businesses that can provide an attractive work environment for this key demographic will have a decided advantage at attracting the best talent. One company that excels in this regard is Google (GOOG 0.37%) (GOOGL 0.35%).

A recent survey by brand research firm Universum asked more than 240,000 business and engineering students which companies they would most like to work for. Google topped the list across every category, including business and engineering students, as well as men and women.

"Millennials want to truly understand a company's purpose, align with it, and work with others to propel the organization's performance," Universum said. "They want to work in innovative settings, unencumbered by infrastructure, while still delivering strong financial results."

Google's mission to "organize the world's information and make it universally accessible and useful" is clearly resonating with Millennials. And few companies are as innovative or financially sound, with Google's massive cash flows helping to fund potentially world-changing research projects on topics as broad ranging as self-driving cars, glucose-sensing contact lenses, drone delivery, and even longer lifespans. If this innovative culture can help Google continue to attract the best and brightest of the millennials, the company could remain at the forefront of technological progress for many years to come.