The use of alcohol and drugs in war zones appears to reflect a broader trend toward heavier and more frequent drinking among all military personnel, but especially in the Army and Marine Corps, the two services doing most of the fighting, Pentagon officials and military health experts said.

A Pentagon health study released in January, for instance, found that the rate of binge drinking in the Army shot up by 30 percent from 2002 to 2005, and “may signal an increasing pattern of heavy alcohol use in the Army.”

While average rates of alcohol consumption in the Navy and Air Force have steadily declined since 1980, the year the military’s health survey began, they have significantly increased in the Army and Marine Corps and exceed civilian rates, the Pentagon study showed. For the first time since 1985, more than a quarter of all Army members surveyed said they regularly drink heavily, defined as having five or more drinks at one sitting.

The rate of illicit drug use also increased among military members in 2005, to an estimated 5 percent, nearly double the rate measured in 1998, a trend that the study called “cause for concern.”

The study also found other health problems in the military, from the growing popularity of chewing tobacco to a 20 percent increase during the past decade in service members who are considered overweight.

Lynn Pahland, a director in the Pentagon’s Health Affairs office, said the rising rates of heavy drinking and illegal drug use among active-duty military personnel are particularly troubling inside the Defense Department. “It is very serious,” Ms. Pahland said in an interview. “It is a huge concern.”

In the military, seeking help for psychological problems, including alcohol and drug abuse, is considered a taboo, especially among officers competing for promotions. Several officers interviewed for this article said the Pentagon was not doing enough to reduce that stigma.