Drew Brees is the leading spokesman of AdvoCare, a multilevel marketing company that generated $719 million in net revenue last year.

AdvoCare boasts an army of 640,000 salespeople, up from 97,000 in 2010. These independent distributors sell energy drinks, shakes and supplements directly to consumers. In 2014, only 0.54 percent made $10,000 from the company and just 0.06 percent exceeded $100,000.

As AdvoCare has grown, it has signed dozens of high-profile athletes as endorsers, including NFL QBs Andy Dalton, Philip Rivers and Alex Smith, MLB pitcher Doug Fister and CrossFit champion Rich Froning.

The promise is that if you sign up for AdvoCare, you can reap "rewarding" financial results -- draws tens of thousands of new distributors every year. But an Outside the Lines/ESPN The Magazine investigation has found that few of those salespeople will ever achieve that vision. 

"They plant the seed that you're gonna make money -- life-changing money," says Gabriel Chavez, who joined in 2010.

While MLMs do rely on direct sales of products to customers, they also pay their salespeople commissions based on their recruits' purchases and, in turn, on the purchases of their recruits' recruits.

Salespeople are given the line: "If Drew Brees takes it, why wouldn't you?"

Brees, along with the other athletes who sign with the company -- Carli Lloyd, Sam Bradford and Wes Welker are all past endorsers -- are integral to a popular AdvoCare sales and recruitment technique called the "Bulletproof Shield." 

Since joining AdvoCare, Brees says he's been stopped on the streets by "literally thousands of people" who tell him how the company has changed their lives: "I have literally NEVER had a single person come up to me and say anything negative about AdvoCare products or the business model." He adds, "I see the lives that it changes, not only as a direct result of taking the products but the financial independence it gives many of its distributors.

"Why are all these people involved in AdvoCare?" he continues. "Because it's a viable business, and they believe in the products, what they are selling and in AdvoCare. And so do I."