IOWA CITY (AP) - Anyone planning a New Year's resolution to eat healthier may want to get the kids involved.

A new study led by a University of Iowa doctor shows adults living with children eat more saturated fat - equivalent to almost a pepperoni pizza per week - than adults who don't live with children.

"It's important because it shows you can't just change the diet of one person in the household," said Dr. Helena Laroche, the study's primary author and an associate in internal medicine and pediatrics at the University of Iowa Carver College of Medicine. "We really need to focus on the whole family."

The study is the first to show how children may influence adults' food intake, Laroche said. Studies typically examine how adults affect children's eating habits.

Laroche, who joined the university in September, and colleagues at the University of Michigan Health System analyzed questionnaires given to 6,600 adults across the nation living with and without children under age 17.

Adults living with children ate 4.9 more grams of fat daily, including 1.7 grams of saturated fat, than adults living without children. A slice of pepperoni pizza - frozen, thin crust varieties - has about 2 grams of saturated fat. Deep dish pizzas have more.

The study showed adults with children in the home were more likely to eat foods such as cheese, ice cream, beef and pizza, as well as salty snacks, which also tend to be high in fat.

"Once these foods are in the house, even if bought for the children, adults appear more likely to eat them," Laroche said.

She said unhealthy food choices may be due to time pressures and adults' perception that children would not eat foods with less fat.

The study, funded by the National Institutes of Health and other entities, will appear early next year in the online edition of the Journal of the American Board of Family Medicine.

Laroche said she became interested in researching household eating habits through her patients.

"I've heard this over and over again: 'My diet went downhill after I had children,"' she said.

Despite the convenience of pizzas and salty foods, Laroche said adults should find eating alternatives that could improve their lifestyles. Diets high in saturated fat can increase the risk of heart disease, stroke and some cancers and can lead to weight gain.

Laroche offers her patients several diet tips:

- Choose popcorn or low-salt pretzels over high-fat potato chips.

- Children 2 or older can be given lower fat, instead of whole milk.

- Avoid cooking in butter, lard or margarine; try baking or cooking in olive oil.

- Limit the amount of fast food and pizza to once a week or less.

- Look for lower fat items on the menu and eat smaller portions.