One fast-growing American industry has become a conspicuous beneficiary of the recession: for-profit colleges and trade schools.

At institutions that train students for careers in areas like health care, computers and food service, enrollments are soaring as people anxious about weak job prospects borrow aggressively to pay tuition that can exceed $30,000 a year.

But the profits have come at substantial taxpayer expense while often delivering dubious benefits to students, according to academics and advocates for greater oversight of financial aid. Critics say many schools exaggerate the value of their degree programs, selling young people on dreams of middle-class wages while setting them up for default on untenable debts, low-wage work and a struggle to avoid poverty. And the schools are harvesting growing federal student aid dollars, including Pell grants awarded to low-income students.

“If these programs keep growing, you’re going to wind up with more and more students who are graduating and can’t find meaningful employment,” said Rafael I. Pardo, a professor at Seattle University School of Law and an expert on educational finance. “They can’t generate income needed to pay back their loans, and they’re going to end up in financial distress.”