Vani Hari, aka the Food Babe, wants Chick-fil-A to ditch high fructose corn syrup and artificial dyes, take certain chemicals out of its food and use chickens raised without antibiotics or genetically modified feed.

Earlier this month, she got part of her wish. The Atlanta fast-food giant said it would drop the syrup from its white buns and dyes from its sauces and dressings.

That was two years after Hari posted a story on her website, foodbabe.com, with the headline “Chick-fil-A or Chemical-Fil-A?”

“I am totally stunned at the amount of responses I’ve gotten from this and what I’ve been able to change in such a short time,” said Hari, a former management consultant who operates her blog from Charlotte.

Hardcore corporate critics still protest at headquarters or back gadfly shareholder proposals. But as Hari’s influence on Chick-fil-A shows, much activism has shifted to the Internet.

Using the web and social media, people are prodding changes without leaving their homes. Online petitions forced retailer Abercrombie & Fitch to include larger sizes in their clothing inventory. A barrage of online complaints got GAP to revert to its old logo.

Ken Bernhardt, a Georgia State University marketing professor, said people who might have told a handful of friends about a product problem or service issue can now cast a much wider net via social media.

At the same time, companies employ teams of people to monitor sites like Twitter. That allows them to quickly jump on issues, and to learn about concerns faster than their own research would reveal them.

To be sure, gripes that lead to change are still lightning strikes in the online forest, which offers a 24/7/365 platform for venting of every conceivable stripe. In most cases it takes a fairly sophisticated approach to create a viral cause with staying power.

“It’s not the isolated comment that typically causes change,” Bernhardt said. “Somebody who has 25 Facebook friends probably isn’t going to have much impact… . Someone who writes a blog with thousands of followers will be listened to.”

Moreover, changing broader corporate practices such as wages or benefits, organizing unions and creating substantial social change generally requires years of work that go beyond the computer screen.

But online causes can catch fire when the timing is right. When Molly Katchpole in 2011 started a Change.org petition that challenged Bank of America’s move to charge a monthly $5 fee for debit cards (a surcharge other banks quickly followed), she had low expectations. The recent college graduate was nannying and working with a political consultant, and simply wanted a response from the bank.

But Katchpole’s petition came weeks after the Occupy movement started, and people latched on to the tangible demand.

After the petition drew more than 300,000 signatures in one month, Bank of America rescinded the fee.

“If it had been out of the blue, it might not have taken off as much,” she said. “The moment has to be really strong.”

Hari’s blog has taken off as people pay more attention to healthy eating. Abercrombie & Fitch, which for years courted controversy, added sizes as anti-bullying campaigns grew popular.

Bernhardt said successful campaigns often bring attention to health and safety concerns, affect a company’s brand reputation or bottom line, or cost little to implement.

Katchpole said the success of her Bank of America campaign came in part because she was savvy with Twitter and was able to universalize concerns to unite people across the political spectrum.

“One person can get a conversation started, but it takes a lot of people to make long-term changes that are going to happen,” she said. “It needs a good storyline, something that makes sense to a lot of people.”

Hari’s blog is far more than the bare-bones musings of a food industry critic. Besides the catchy name — accompanied by plenty of photos of Hari — it features a professional layout and a commercial look complete with links for shopping.

Two years ago, she looked into chains with a reputation for healthy fast-food or fast-casual menus, including Chick-fil-A, Chipotle and Atlanta-based Moe’s Southwest Grill.

From her inquiries, she said she learned that Chick-fil-A used artificial dyes, MSG and TBHQ, a chemical made from butane. Hari also said the chain uses antibiotics and genetically modified products in its chicken feed.

As a result of her 2011 post questioning ingredients in the chain’s food, Chick-fil-A invited her to visit in December 2012 and paid her a consulting fee to talk about ingredients. The company has been changing ingredients in some products since 2006, including removing high fructose corn syrup from dressings and bread while reducing salt across the menu, spokesman Mark Baldwin said.

Managers who met with Hari “were happy to see how much our ideals align,” Baldwin said in an email.

“We have been in touch with her frequently over the past several months to provide updates on menu changes, including our most recent news that we’ve removed yellow dye from our Chicken Soup recipe,” he said.

Baldwin said the chain is testing the removal of high fructose corn syrup from dressings and sauces, artificial ingredients from buns, and TBHQ from peanut oil.

Hari said in a recent blog post that her No. 1 request, “to provide safer and more sustainable chicken that is raised without antibiotics and GMO feed and that is not grown in terrible living conditions” has yet to be addressed. She also wants the MSG gone.

Hari also has led efforts to reduce the dyes in Kraft Foods’ popular macaroni and cheese line. After learning that the company eliminated dyes in British versions, she challenged it to do the same in the United States.

Kraft spokeswoman Lynne Galia said in an email the company is “always listening to consumers.”

“In this particular case, we’ve been working on the relaunch for quite some time,” she said. “It is completely in line with our company’s ongoing efforts to deliver better nutrition in our products while also delivering against taste expectations.”

In the decade she has been active online, Hari said, she has been surprised by her success. She credits her reader base, which she calls the “Food Babe Army.”

“It’s all be been my voice, but my voice has been amplified by so many of my followers,” she said.