They are young, hip, fly ... and fat.

College students turn out to be not the icons of youthful energy and sex appeal, but instead could be the poster-kids for America's ever-expanding waistline.

Results from an ongoing survey reveal that university students lead generally unhealthy lives, characterized by little physical activity and unwholesome diets.

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For instance, nearly half of the male students surveyed were overweight or obese, while almost 30 percent of the female students were considered overweight or obese.

Even the scientists were surprised by the results.

"We were astounded," said study team member Joanne Burke of the University of New Hampshire.

Obesigenic environment

Part of the problem, explained Burke, is the time spent in front of a screen for video games and TV watching.

"I think it's a combination of the obesigenic environment," Burke said. "There's food at every corner; portion sizes have gotten bigger; students have gotten bigger."

The research, which was presented at a meeting of the American Physiological Society earlier this month in Washington, D.C., sheds light on the lifestyles of an age group for which little is known.

"We don't have great data on [college-age students]. We assume they are healthy," said one of the study scientists, Jesse Morrell, a nutrition and obesity scientist at the University of New Hampshire.

Late adolescence is a time when lifestyle decisions are still in flux from parent-guided to self-guided, so it's a smart time to mold healthy habits.

"We know this is a time in their lives where they are making those independent lifestyle choices," Morrell said. "They are no longer with their parents or caregivers. And we think intervention here may be optimal."

College menu

As part of the university's Young Adult Health Risk Screening Initiative, the scientists surveyed nearly 800 college students, ranging from 18 to 25 years old, about their daily activities and eating habits.

They also measured participants' weight, blood pressure and indicators for heart disease and diabetes.

Some of the numbers are based on a smaller sample size, because for some measurements, such as dietary history, all of the participants didn't complete the associated form.

The men reported eating about 2,700 calories a day, while the women consumed about 1,800.

But quantity might not be as informative as food quality. More than 80 percent of all students weren't getting enough potassium in their diets, and many students didn't meet the Food and Drug Administration's recommended levels for key bone-health nutrients calcium and vitamin D.

Junk food could be partly to blame for some of the results.

Most students, 95 percent of the men and 70 percent of women, consumed too much sodium, above the upper tolerable limit of about 2,300 milligrams a day.

"Sodium is a nutrient found in a lot of foods, but we tend to get most of it in our diets from processed foods," Morrell told LiveScience.

And for the college men, sodium consumption was linked with high blood pressure, recorded from a one-time screening.

More than half of the men and about 20 percent of the women showed high blood-pressure readings.

"This population is a young group, and we don't often think of them in terms of hypertension and treating them for high blood pressure," Morrell said.

One positive finding: The students who ate at UNH's dining hall showed higher intakes of folate, a B-vitamin found in citrus fruits, tomatoes and leafy green vegetables.

For women, folate intake has been linked with lower blood pressure.

Sedentary students

As a whole, about one-third of the students had body mass indexes (BMI) in the overweight range and about 10 percent were considered obese.

The expanding waistlines could be due to both overeating and junk-food consumption, as well as lack of exercise.

About one-third of the students reported being "inactive," with fewer than 30 minutes a day of physical exercise.

Moderate physical activity is defined as an activity that burns about 150 calories of energy per day.

The more vigorous the exercise, the less time each day is needed to meet these requirements. Examples from the Centers for Disease Control and Prevention (CDC) include:

—Washing and waxing a car: 45-60 minutes

—Playing volleyball: 45 minutes

—Gardening: 30-45 minutes

—Walking 1.75 miles: 35 minutes

—Dancing fast (social): 30 minutes

—Running 1.5 miles: 15 minutes

—Shoveling snow: 15 minutes

The consequences of inactivity

Female students who reported being inactive were more likely to have a higher number of risks for metabolic syndrome compared with females participating in more than 90 daily minutes of exercise.

Metabolic syndrome is characterized by a group of five factors, including abdominal obesity, high blood pressure, high blood sugar, high blood fatty acids and low levels of HDL (considered the "good cholesterol").

The syndrome has been shown to increase a person's risk of heart disease and type-2 diabetes.

More than 50 million Americans have metabolic syndrome, according to the American Heart Association.

The scientists want to expand their study to include more direct measurements of activity, perhaps having students wear pedometers.

Morrell said the first step in improving the situation is to get a baseline for how healthy or unhealthy college students are.

"We think intervention here may be optimal, but we need to start somewhere," Morrell said.

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