Seven men atop Pikes Peak are munching on liquid protein and fiber bars - with bagels and popcorn for treats - in hopes of determining what the human body prefers at high altitudes.

The $250,000 project has taken the seven from sea-level to 14,000 feet, always eating the same stuff.For the 12 investigators, it has been nerve-wracking.

"The whole thing could be destroyed so easily," said Lorna Moore, a co-investigator and professor of anthropology at the University of Colorado in Denver. "Any kind of accident (an injury, a mistake in data collection), and it would be over."

Moore and others suspect that high altitude prompts the body to change its preference for carbohydrates to a preference for fat.

They base their suspicions on a seemingly paradoxical change in blood chemistry at high altitudes: Although lactate, a waste product of the body's metabolism, typically increases when oxygen is in short supply, it is known to decrease at high altitudes.

Digesting fat produces less lactate than that of carbohydrates, Moore said, and could explain the paradox.

Should the suspicion prove true, the researchers think the peak's latest research project could help tourists and Colorado newcomers adapt to high altitudes.

The project, headed by Dr. Jack Reeves, a medical professor at the University of Colorado Health Sciences Center in Denver, also could assist in developing drugs to treat chronic lung and heart problems, Moore said.

Since the start of summer, most meals eaten by the seven subjects, ages 20 to 32, consist of liquid proteins with fiber-and-energy bars. Each also gets a bagel with cream cheese for breakfast, popcorn in the evenings and, for some, apples that are carefully weighed and recorded on the subject's chart.