But as lives grow busier — and waistlines grow larger — a number of nutritionists are calling for Americans to reduce their risk of cancer and other diseases by cooking at home more and eating out less.

"The more you eat in, the more you can control and the healthier your plate is going to be," says Rachel Brandeis of the American Dietetic Association. "I wish people would think that when they are eating, they could be lowering their cancer risk."

When dining out, people tend to gravitate toward all the wrong things, says Brandeis, a registered dietitian.

People consume 50 percent more calories, fat and sodium when they eat out than when they cook at home. And restaurant customers often miss out on fruits, vegetables, whole grains, beans and other vitamin-rich "powerhouse foods" that may reduce the risk of cancer, Brandeis said.

Experts believe up to one-third of cancers are related to diet. Diets filled with red meat but few vegetables, for example, have been linked to several kinds of cancer. And overeating — which may be harder to avoid at restaurants — can lead to obesity, which increases the risk of postmenopausal breast cancer, as well as cancers of the colon, kidneys, esophagus, endometrium and other tissues, according to the National Cancer Institute.

Surveys show that Americans are eating out more and more.

"We're eating in front of our cars, we're eating in front of the TV, but we're not sitting down as families," Brandeis says. "We're more sedentary than we've ever been, and we're fatter than we've ever been."

Nutritionists know it's not easy to break old habits. Many people say they barely have time to exercise, let alone fix dinner.

Brandeis, a mother of two, says her secret is organization.

She cooks six nights a week, even though she and her husband both work. She spends 15 to 20 minutes planning a week's worth of menus and writing a grocery list. She shops just once a week.

Brandeis says she opts for easy cooking methods, too. In the winter, she tosses vegetables in a crockpot. In the summer, she grills. When cooking chicken, she prepares extra to use in salads or sandwiches the next day.

The American Institute for Cancer Research, which focuses on nutrition and cancer, has produced a guide filled with tips like these, called "Homemade for Health" (www.aicr.org).

Melanie Polk, the institute's director of nutrition education, says cooking at home has many benefits. It teaches children about nutrition as well as the importance of sharing household chores.

Kirstin Kristinus of Washington, D.C., says cooking at home brings her family together. Her 4-year-old daughter enjoys helping in the kitchen and spending extra time with her mother.

Kristinus also strives to reduce her family's cancer risk with every meal.

She plans her menus around whole foods, such as blueberries, tomatoes or broccoli. If she cannot cook herself, she leaves menus and recipes for her nanny or husband.

"I want to make sure that these food groups are being served every day," says Kristinus, 39, a homemaker with two children.

Though experts dispute the particular health benefits of individual foods, they agree that people should aim to include as many colors and textures as possible.

"The only way to know that you are getting all the beneficial things is to expose yourself to a wide variety of these plant chemicals," says Steven Shiff, a doctor at the Center for the Study of Diet and Nutrition at the Cancer Institute of New Jersey. "If you eat on the run or out at a restaurant, it's a lot easier to choose unhealthful things."

Dietitians suggest bringing homemade lunches to school and work, along with fruit or nuts for a mid-afternoon snack.

"Your body needs to be refueled every three to four hours, and it's a great opportunity to get something healthy," Brandeis says. "There is nothing healthy in a vending machine."

Nutrition experts say families don't have to swear off restaurants. They may have to work harder to avoid temptation, however, and ask detailed questions about the menu.

"It is possible to eat healthfully if you eat outside the home," Shiff says. "But it takes probably the same sort of planning that you would have to do to prepare meals at home."

Ways to make home cooking healthful

The Washington-based American Institute for Cancer Research (www.aicr.org), which focuses on the link between diet and cancer, has produced a booklet called "Homemade for Health." Melanie Polk, the institute's director for nutrition education, suggests these tips:

• Buy frozen, pre-cut vegetables or prewashed greens. Toss vegetables into salads, pasta sauces, stews, lasagnas, pizzas, quiches, sandwiches or omelets.

• Buy bags of frozen berries for breakfast smoothies.

• Reclaim prime time. Instead of taking your dinner into the family room — by eating takeout food on the couch — take the TV into the kitchen. Ask the entire family to help prepare dinner while watching their favorite shows.

• In place of shuttling kids between games and lessons — and stopping for fast food on the way home — cancel one activity a week and ask the children to help you make dinner.

• When using prepared foods or frozen dinners, add one or two steamed or microwaved vegetables to the plate.

• Choose the right ingredients. Red or tan new potatoes give a meal extra fiber, for example, but don't need to be peeled.

• On the weekend, cook an extra-large batch of a healthy dish, divide it into individual servings and freeze small portions for later.

• When making tomato sauce, tacos or fajitas, use twice as many vegetables but half as much meat or cheese.

• Stock the pantry with healthful foods that can be prepared quickly, such as minced garlic and canned chickpeas.

• To coax kids into eating more vegetables, purŽe the veggies into soups.