– Caleb Torres lost seven pounds his freshman year of college — and not because he didn't like the food in the dining hall. A first-generation college student barely covering tuition, Torres ran out of grocery money halfway through the year and began skipping meals as a result.

He'd stretch a can of SpaghettiOs over an entire day. Or he'd scout the George Washington University campus for events that promised free lunch or snacks. Torres told no one what he was going through, least of all his single mom.

"She had enough things to worry about," he said.

Torres isn't alone. Researchers say hunger affects millions of U.S. college students every year.

According to a first-of-its-kind survey released Tuesday by researchers at Temple University and the Wisconsin HOPE Lab, 36 percent of students on U.S. college campuses do not get enough to eat, and a similar number lack a secure place to live. The report, which is the first to include students from two-year, four-year, private and public universities, found that nearly 1 in 10 community college students have gone a whole day without eating in the past month. That number was 6 percent among university students.

A survey of University of Minnesota students by Boynton Health Services showed that 10 percent of U students didn't have adequate food and 17.5 percent worried about running out.

Researchers blame ballooning college costs, inadequate aid packages and growing enrollment among low-income students — as well as some colleges' unwillingness to admit they have a hunger problem. College hunger is not a new issue, researchers say. But it appears to be growing worse, and not just because college is getting more expensive.

"Prices have gone up over time," said Sara Goldrick-Rab, a professor of higher education policy at Temple and the lead author of the report. "But the rising price is just a piece. This is a systemic problem."

Goldrick-Rab's report is based on data from 43,000 students at 66 schools and used the Department of Agriculture's assessment for measuring hunger. That means the thousands of students it classifies as having "low food security" aren't merely avoiding the dining hall or saving lunch money for beer: They're skipping meals, or eating smaller meals, because they don't have enough money for food.

On top of that, the report found, 46 percent of community college students and 36 percent of university students struggle to pay for housing and utilities. In the past year, 12 percent of community college students and 9 percent of university students have slept in shelters or in places not intended as housing, or did not know from one day to the next where they would sleep.

Experts say the factors underlying campus hunger are complex. More low-income students are enrolling in college, thanks to expanded needs-based scholarship and grant programs, a move away from standardized test scores as part of the application process, and other initiatives designed to recruit more diverse students.

But once they get on campus, low-income students often find that the patchwork of grants and scholarships they've assembled are not enough to cover all of their expenses.

In the 2013-14 academic year, room and board for the average undergraduate totaled $9,929, according to the National Center for Education Statistics, a 50 percent increase over 20 years prior. And those figures are higher for private and four-year colleges.

Torres will graduate from George Washington in May. With little initial support at school, Torres moved off-campus sophomore year on the advice of a friend, renting a room in the home of a middle-aged couple known for helping down-on-their-luck students.

Torres says he hasn't worried about food since then — and that he feels "blessed every day."