If there were ever a reason to cut back on kids' consumption of cake, cookies, pizza and soda, nutrition experts say a new study highlights just how unhealthy young people's diets really are.
Researchers from the National Cancer Institute in Bethesda, Md. analyzed data from the National Health and Nutrition Examination Survey and found that nearly 40 percent of calories consumed by children ages 2 to 18 were empty calories, the unhealthiest kind of calories.
Half of these calories came from just six foods:
Sugary fruit drinks
Grain desserts, such as cake, cookies and donuts
Dairy desserts such as ice cream
Whole milk, which is far fattier than skim.
"Consumption of empty calories far exceeded the corresponding discretionary calorie allowance for all sex–age groups," wrote the researchers, led by nutritionist Jill Reedy.
"This number is staggering and depressing," said Kelly Brownell, professor of psychology, epidemiology and public health at Yale University.
While the findings don't surprise many nutrition experts, they say the reasons kids consume so many empty calories are complex. The push for healthier foods over the past few years has helped a little, but they say there are still many obstacles to changing eating habits for the better -- including a lack of physical activity, parental and peer influences, and marketing by the food industry.
"Empty-calorie foods are manufactured by the food industry to be maximally palatable," said Dr. David L. Katz, director of the Yale University Prevention Research Center in Derby, Conn.
"I don't see a solution unless we have serious limits on advertising of foods that damage the health and reduce the longevity of today's children," said Dr. Walter Willett, chair of the department of nutrition at the Harvard School of Public Health in Boston.
But the picture is complex, said Connie Diekman, director of university nutrition at Washington University in St. Louis. Many kids -- and their parents -- simply do not know what they ought to be eating.
"Nutrition education needs to start in prenatal classes and move through the entire education system," said Diekman. "As I work with college students it amazes me, the number who don't know the nutritional value of many foods or even how much of each food group they need."
"The school curriculum must include thorough teaching of the value of real food and what food to avoid," said Dr. Jana Klauer, a New York-based physician and nutrition expert. "It is crucial that nutrition be addressed thoroughly throughout the elementary school years; high school is too late because the damage has been done by then."
This summer, the Senate passed a bill that would provide $4.5 billion to help improve the nutrtional quality of school lunches and the food in vending machines. The bill has yet to pass the House of Representatives.
Another nutritionist blames teen culture for the over-consumption of junk food.
"Fast food is very inexpensive, filling, and tasty," said Joanne Ikeda, nutritionist emeritus at the University of California, Berkeley. "Teens view it as a bargain. They don't want to spend a lot of money on food. They want to spend it on clothes, shoes, iPhones, etc.," she added.
Experts also believe children's poor diets are a result of their home environment.
"Eating is learned behavior. Kids eat what their parents eat," said Dr. Charles Clark, professor of medicine at Indiana University School of Medicine. If busy parents throw a frozen pizza in the microwave, he said, that's a bad meal that sends a bad message.
"[We need] better food labeling, including fruits and vegetables, clarification of serving sizes ... [and] food labeling with caloric content," said Dr. Robert Eckel, a professor of medicine at the University of Colorado Hospital.
One nutritionist said that while the food industry does serve up a less-than-healthy dose of junk food, restaurants are improving their choices, and it's up to consumers to make the right choices.
"[W]e need for customers to continue to ask for healthier options. Change won't happen in these environments unless customers financially support the changes," said Diekman.
The Grocery Manufacturers Association, an organization that represents 300 food, beverage and consumer product companies, said that between 2002 and 2009, food and beverage companies have introduced thousands of healthier alternatives.
"Food and beverage companies are responding to consumer needs by providing thousands of healthier product choices that make it easier for shoppers to build a healthy diet for them and their families," the association said in a press release.
The association also said more than 90 percent of its companies actively promote healthy lifestyles.
Despite the National Cancer Institute study's findings, the director of the U.S. Centers for Disease Control and Prevention called the obesity epidemic a "winnable battle."
"CDC is committed to addressing the epidemic of obesity and overweight in the U.S.," says the agency's website, "and improving the public's health through the promotion of good nutrition, physical activity, and a safe food supply."