It's hard to blame people for craving fast food when they are inundated with advertising from such a young age. But what’s disturbing is just how far fast food companies will go to target kids from groups already more likely to suffer from obesity – including the poor, rural Americans and black Americans.

In a new study, a team of researchers at the University of Illinois at Chicago and Arizona State University found that fast food chains in predominantly black neighborhoods were more than 60 percent more likely to advertise to children than in predominantly white neighborhoods. The researchers also found that fast food restaurants in middle- and low-income areas tended to direct their ads toward children more often than those in high-income neighborhoods, and those in rural communities tended to market their products to kids more often than those in more urban settings

"Fast food restaurants in black neighborhoods have significantly higher odds of using kids' meal toy displays to market their products to children compared to restaurants in white neighborhoods," said Punam Ohri-Vachaspati, the lead author of the study. "The associations we observe are troubling because we know that black children are at higher risk for consuming unhealthy diets including fast food, and have higher prevalence of obesity."

The Burger Kings and McDonald's of America have long known that dangling toys and other paraphernalia to children is a choice way to keep them coming back — or, at the very least, asking their parents to return. But the study, which analyzed data from more than 6,700 restaurants around the country, has finally sketched out precisely how this is happening.

More than 20 percent of all the restaurants, and 31 percent of the chain restaurants used child-directed marketing -- a category that includes advertisements with cartoon characters, television personalities, movie stars, and sports figures, as well as displays with kids' meal toys, three-dimensional cardboard cut-outs, and play areas.

The danger of pitching french fries, hamburgers, and other fast foods to kids is that it can lead to an unbalanced and potentially harmful diet -- not only in childhood, but in adolescence and even adulthood. Children who eat fast foods tend to eat more calories, fat, sodium, and sugars, and less fruits, vegetables, and dairy than those who don't. Eating fast food has also been found to cause higher body fat and insulin levels in adolescence, and an increased risk of obesity in adulthood.

Already, fast foods account for too many calories and feed too many children in this country. Nearly a third of American kids between the ages of 2 and 11 — and nearly half of those aged 12 to 19 — eat or drink something from a fast food restaurant each day, according to a study from 2008. And fast food accounts for roughly 13 percent of total calories eaten by children and teenagers aged 2 to 18 in the United States.

While the American love affair with fast food is in some ways subsiding—as seen by fast food giants like McDonald's, that are struggling to attract customers—some people are still hooked. A Gallup poll from last year found that some 16 percent of people in the country eat fast food several times a week, while nearly a third still eat it once a week.

Fast food restaurants blanket the country, but they are especially ubiquitous in the country's poorer communities. This reality, which has been called "food oppression," is a crucial component of a growing systemic problem in the United States, whereby America's richer communities are eating better, while its poorer communities are eating worse.

Poor black communities are especially vulnerable to this phenomenon.

"The same black communities that suffer more from diet-related diseases, like heart disease, obesity, and diabetes, tend to consume more fast food," said Dr. Jennifer Harris, the Director of Marketing Initiatives at Yale's Rudd Center for Food Policy & Obesity.

In her research, Dr. Harris has found that individual fast food restaurants, including Popeye's and Papa John's, "definitely target that audience [African-Americans]." She said they do this, for instance, by purchasing ads on channels popular with black audiences like BET.

This particular study, though it also assessed the frequency with which fast food companies advertised to specific demographics, did not look at whether the content of the ads was different depending on the audience.

The government does not currently regulate marketing practices in the fast food industry. Chains like McDonald's have launched voluntary initiatives to improve the quality and nutrition of the foods they offer to children, and committed to shifting their kid-focused marketing to healthier items. Examples of industry initiatives include the Children's Food and Beverage Advertising Initiative, which promises to curb the advertising of unhealthy foods, and Kids LiveWell program, which is meant to boost to the number of healthy offerings at fast food restaurants.

"Since January 2013, 100 percent of our national communications to children under the age of 12 have contained a nutrition or active lifestyle message," McDonald’s told Businessweek last year. (Industry officials did not immediately respond to requests for comment.)

But progress has been limited. So far, most television advertisements targeted at children still seem to tout unhealthy foods too, and the bulk of foods offered to children still offer little to no nutritional quality. The average child between the ages of 2 and 11 sees nearly 200 commercials for McDonald's Chicken McNugget Happy Meals on television, and another 23 for Burger King's Kids Meals each year. Fast food restaurants also still spend upwards of $700 million each year to market their foods to children and teenagers.

Given the public health stakes, it might be time to reconsider whether the industry is capable of regulating itself.

"The companies will argue that they can't control it if some people eat more fast food than others, but at the same time, they're increasing the disproportionate demand through their marketing," Harris said. "For that reason regulating marketing in fast food companies is the only way to solve this problem."