Eating out costs you an extra 200 calories per day, study says

(CNN) -- It's often difficult to find time to cook a healthy, nutritious meal while traversing this hectic world.

Despite our better judgment, fast food is our go-to for convenience. But skipping the drive-thru for that "healthier" sit-down meal at a restaurant isn't always a good option either, a new study suggests.

The study, published online Thursday by Public Health Nutrition, concludes that eating at both fast food and full-service restaurants leads to "significant increases in energy, sugar, saturated fat and Na ."

Researchers analyzed data from over 12,000 people aged 20 to 64 who were asked about their eating habits on two separate days. The data was collected by the National Health and Nutrition Examination Survey.

Around 30% of the study participants ate at a fast food establishment on both days. On day one, 28% of participants ate at a full-service restaurant; 20% ate at a restaurant on day two. The rest of the participants ate at home.

People who ate at a fast food or full-service restaurants consumed an extra 200 calories per day on average than people who ate at home, the study authors say. These extra calories made up about 10% of their total daily intake.

Black adults who ate out consumed more calories on average than white or Hispanic adults who ate at a fast food or full-service restaurant. Eating out affected high-income adults the least, suggesting they may purchase healthier, often more expensive, fare at restaurants.

"On days when people are consuming fast food and full-service restaurant foods, they do not reduce their calorie consumption in other areas of their diet," Binh Nguyen, co-author of the study, concluded.

The researchers also found people who ate out consumed more sugar, salt and saturated fat. In some cases, eating at a full-service restaurant was worse: the study authors estimate there was nearly a 20% increase in daily sodium intake due to restaurant eating, compared to 13% from fast food.

The unhealthy state of American diets is nothing new. More than one third of adults in the United States are obese, according to the Centers for Disease Control and Prevention -- that equates to about 79 million people.

There are many factors behind the increasingly obese population. Portion and beverage sizes have exploded. Public health experts estimate that Americans eat a third more calories than they did 40 years ago, including 56% more fats and oils.

Nguyen has some recommendations for those on the go, trying to eat healthy despite the calorie surplus: "You may want to order a half portion, get the sauce or dressing on the side, and drink water rather than soda to cut down on the additional caloric intake."

The authors acknowledge that the data for this study was self-reported, and that participants may have overestimated or underestimated their calorie intake. But the most important thing to glean from the study, according to co-author Lisa Powell, is that "eating out at restaurants should be the exception not the norm."