Schlosser warned about 550 people at Ryan Family Auditorium on Friday of the dangers he said the fast-food industry poses to consumers.

Schlosser, whose books “Fast Food Nation” and “Reefer Madness” simultaneously made the New York Times’ bestseller list, said the fast food industry needs stricter government regulations, but consumers also can effect change with their personal choices. When NU students go to Evanston’s Burger King, they are sustaining the fast-food industry.

“Every dollar you spend there just has a ripple effect down the production line,” Schlosser said.

Students for Environmental and Ecological Development brought Schlosser to Northwestern to raise awareness about the power of choice, said Weinberg senior and SEED co-chairman Matt McCormick.

Schlosser’s speech extended to NU’s food service when an audience member asked about dorm food. Schlosser said SodexhoUSA might be below McDonald’s on his personal list of food companies.

“The difference between Sodexho and McDonald’s, to my knowledge, is that McDonald’s has not run any prisons,” Schlosser said. “I hope the food you’re getting here is better than the food in the prisons.”

In addition to addressing how Evanston fast-food restaurants and dorm food affect NU students, Schlosser talked more generally about the production and marketing of fast-food companies. He said companies such as McDonald’s employ livestock methods that are unsafe for animals and unhealthy for consumers. Cattle used by fast-food chains are living in their own filth, and meat packaging companies address this problem not by giving cattle more land but by feeding them antibiotics, Schlosser said.

“Seventy percent of the antibiotics sold in the U.S. are being given to livestock,” he said.

Fast-food companies also need to be more responsible in their marketing, Schlosser said, because they are helping to form the eating habits of children — and they target even toddlers.

“Among toddlers in the U.S., 21 percent, about one-fifth of American toddlers, are eating french fries every day, ” Schlosser said.

Unhealthy food choices can lead to obesity, Schlosser said, adding that two-thirds of American adults and one-quarter of American children are obese or overweight.

Schlosser said people can combat both unhealthy eating and unethical fast-food practices by choosing more organic options. He acknowledged the higher cost of organic food but said prices are coming down.

“Of all the things to spend money on, it’s probably better to spend a little more on your food,” Schlosser said.

Some students said they became more aware of their impact on Evanston restaurants after listening to Schlosser. Weinberg sophomore Lauren Berger said she is a vegetarian, but Schlosser’s talk made her evaluate all food she buys and its effect on sustaining fast food companies.

“It really made me think a lot about even getting things like french fries and milkshakes,” Berger said.

Schlosser said “Fast Food Nation” started as a two-part piece for Rolling Stone magazine. Between researching and writing the article and then writing the book, Schlosser said, he worked for about three years on this project.

Schlosser said he hopes to finish his next book about prisons by the end of the summer.

An audience member asked about a sequel to “Fast Food Nation,” and Schlosser’s response elicited applause.

“I just saw ‘Matrix Revolutions,’ and sometimes it’s best to leave it alone,” Schlosser said.