Women tend to eat more calories and fat when dining out, regardless of what their usual eating habits are, new research suggests.

The study, which included both binge-eaters and dieters, found that both groups of women ate out frequently -- and downed between 200 and 300 extra calories a day in the process.

Moreover, women who were prone to binge-eating problems often overindulged when eating out. One-third of their bingeing "episodes" over the two-week study occurred in a restaurant, according to findings published in the Western Journal of Nursing Research.

"Restaurants may present a high-risk environment for bingers and dieters, contributing to loss of control and excess consumption," writes study author Dr. Gayle M. Timmerman, an associate professor at the University of Texas at Austin School of Nursing.

Many experts have pointed to Americans' love of dining out as a potential reason for the nation's ever-expanding waistline. Fast food, as well as the hefty portion sizes at restaurants in general, catch much of the blame.

In the new study, Timmerman found that women ate only about a quarter of their restaurant meals at fast-food places, and they usually skipped dessert whenever they ate out.

Still, dieters and binge-eaters alike ate 200 to 300 extra calories, as well as 10 to 16 extra grams of fat, on days when they dined out.

These extras are bound to add up, according to Timmerman. On average, she found, study participants ate at a restaurant or got take-out on seven of the 14 days they were followed.

Over a year, she estimates, that could translate into a 12-pound weight gain.

The fact that binge-eaters often lost control at restaurants counters the idea that bingeing is a solely private habit, according to Timmerman. Indeed, she writes, the "ample delicious food cues" at restaurants are likely to challenge binge-eaters' control.

SOURCE: Western Journal of Nursing Research, November 2006.