She took his advice, enrolling in the one-year MBA program at Instituto de Empresa (IE) Business School In Madrid. Zanetti borrowed money from her family to pay for the degree. And when she graduated in 2003, it took her a full year to land a job as a product manager at a Spanish version of Home Depot, at exactly the same salary she was earning three years earlier, without the MBA.

For years, Zanetti says, she wanted to write a book on her experience but didn't out of fear that it would hurt her career, which included stints as a product manager for Saint-Gobain and ResMed, a medical supplier. Now that she has left the corporate world, Zanetti says, she can tell the truth about the MBA degree.

Her take, in a self-published book called The MBA Bubble: It's just not worth the investment. "There is an education bubble around these kind of degrees," she says. "I don't think they have much impact on people's careers. There are exceptions, of course, in management consulting and investment banking, where the MBA is always valued. But for the rest, it's a nice-to-have degree. It's not that it is harmful to you, but every market expert I interviewed for the book says that what is needed today is specialized knowledge and skills, and an MBA is generalist training."

Zanetti, now 40 and living in France, says it's not like the degree had no value. "I met wonderful people. I met brilliant professors. I learned some interesting business concepts that gave me a global vision about business. It just wasn't worth the cost in time and money. MBAs get high salaries, but the degree has nothing to do with it. I was hired because of my previous work experience at Shell."

She is even advising people to apply to a top school, get an acceptance, and then decline to go. Put the fact on your resume and Zanetti thinks it will have nearly the same value as going to an MBA program for two years. "It's like being an Academy Award nominee instead of an Academy Award winner," she writes. "But the difference between the two is mortgaging our future and accepting the risk of getting stuck with a monumental student loan." When an employer asks why you didn't go to Kellogg or Yale for your MBA, she advises, just tell them, "I preferred to use that time and money to develop strategic skills to benefit my employers' competitive advantage…."

Of course, Zanetti's complaint about the MBA is hardly new. It falls neatly into the growing genre of anti-higher education tirades that decry the rising cost of education and the lack of any guarantees. But what makes her MBA bashing somewhat different is that she has a degree from a prominent European business school and has decided to write a 232-page book trying to convince others to pass on the MBA, the most successful degree in the education industry in the last 60 to 70 years.

She believes that other business graduates would fess up to the same conclusion, if not for the fact that their views would endanger their careers. "There are few people criticizing MBA programs because it makes no sense to say anything bad against their brands," Zanetti says. "I will not make a lot of friends with this book, but I won't make enemies, either."

Asked if she thinks her opinion would apply to MBAs from Harvard, Stanford and other elite business schools, Zanetti says she has no doubt. "The same would apply to Harvard or whatever school because Harvard is three times more expensive," she insists. "The benefits would have cost much more. It breaks a tie if you're competing with someone who doesn't have the degree, but people who have scarce skills an employer needs will get the job over you."

Zanetti says she harbored these doubts and concerns about the degree, especially after being unemployed for a year after graduation. But she largely kept them to herself until leaving the corporate world a little more than a year ago. "I always wanted to have my own business and to teach," she adds. "I didn't intend to write this book."

Then, she published an article in France about her ideas. The opinion piece seemed to resonate with a lot of people, so she wrote The MBA Bubble, which will be published in France next year and was self-published in English this week. She has built a website to promote the book, but she does not openly identify herself as an IE MBA. "My school is not a secret," says Zanetti, who lists her diploma on her LinkedIn profile.

Her primary arguments against the degree? It is oversold by business schools with slick marketing campaigns. Most people enter MBA programs without really understanding the limits of the degree. The education costs too much and delivers too little value. And graduates are often saddled with so much debt that it limits their ability to follow their true passions. They take jobs they don't want simply to pay off their student loans. Even the value of the network a graduate acquires with the degree is exaggerated.

She's unimpressed, if downright skeptical, of data that shows MBAs get average increases ovetheir pre-MBA base salaries of between 120% to 46%. And those averages are for all business schools, not just the prestige brand-name places. Zanetti is also skeptical of surveys that show widespread satisfaction with the degree. One recent survey, based on the opinions of 4,135 MBA alumni, including 963 members of the class of 2011, found that three out of four alumni of the class of 2011 with jobs reported that they could not have obtained their job without their graduate management education.

"Everybody is doing it and everybody still goes," Zanetti sighs. "They take for granted that it is a good investment. Business schools manipulate the statistics.... In France, one school hired a company to make fake [positive] comments in Internet forums. These schools have this university halo around them and talk about the labor market as if they are impartial, but they are not. They continue selling things that do not have value because it has profit."

Zanetti says her experience at IE was not satisfying. "Business schools don't treat you as a customer," she says. "Applicants should not forget that they are customers and are buying something. We were even insulted. One day we were in a meeting room and the professional career director said to us, 'Get out of here you scum.' It was funny to him. I told him, 'What's so funny? I am paying your salary.'"

She says that IE's director of career management also told students it was really hard to change industries with an MBA. "Yet they use it as a marketing claim," she points out. But it is really not true. You really have to fight to change industries. I did change industry but in the same job function."

Zanetti estimates that she uses no more than 20% to 30% of what she learned in her one-year MBA program. As for networking, she shrugs. "You spend time with great people, but you can spend time with great people in many places. It is not unique. You can build your own brand in less time than it would take to pay back your loans."