Diet Coke today introduced the biggest product and marketing makeover in its 36-year history as it looks to regain momentum in the struggling diet soda category by more aggressively targeting millennials. Changes include a logo redesign and four new flavored varieties, such as "twisted mango," that will be sold in slim cans.

The overhaul, shown in this Coca-Cola-produced video, is backed by an aggressive marketing campaign by Anomaly featuring the tagline "because I can" that seeks to inject Diet Coke with a new swagger and grow the brand beyond its loyalist following of female baby boomers.

Ads starting later this month will feature a blend of male and female celebrities and influencers. But the spots steer clear of A-list pop stars like Taylor Swift that have backed the brand in the past. Instead, Diet Coke will use the likes of Karan Soni, an Indian-American actor known for playing a supporting role in "Deadpool." The intent is to keep the focus on the product.

"It used to be that Diet Coke was very glossy … superficial, skewing female," says Rafael Acevedo, Coca-Cola North America's group director for Diet Coke. The new marketing will be "more authentic," he adds, "and is a lot more gender neutral and diverse."

Sticking with aspartame

Notably, the refresh will not include a major formula change, beyond the edition of the the four new flavors, which also include "feisty cherry," "zesty blood orange" and "ginger lime."

That means Coca-Cola is sticking with aspartame. The much-maligned artificial sweetener is often under the cross-hairs of health activists that have linked it to health issues. But the evidence is mixed. The American Cancer Society's position is that "for most people, no health problems have clearly been linked to aspartame use." Diet Pepsi removed aspartame in late 2015, only to see the move backfire as consumers complained and sales dropped. The brand responded by selling aspartame and aspartame-free versions. For its new flavored versions, Diet Coke added another artificial sweetener called acesulfame potassium, or Ace-K, along with aspartame.

For its core variety, Diet Coke marketers did not want to risk a similar backlash as Diet Pepsi, which is why the brand did not tweak its sweetener formula. "We want to make sure that we don't do anything that will compromise in any way the taste," Acevedo says. "We have a huge loyal following that absolutely loves the taste of Diet Coke."

But that following has shrunk in recent years as as calorie-conscious drinkers gravitate to other options like sparkling water and zero-calorie energy drinks. Diet Coke's dollar sales fell 3.7 percent in the 52 weeks ending Dec. 2, according to Nielsen data recently reported by Wells Fargo. But the brand still dominates the diet soda category with 26.3 percent dollar market share. Some 20,000 Diet Cokes are consumed every minute in the U.S., according to the brand. Diet Pepsi, whose sales fell 8 percent in the period, has 13.4 percent share.

Diet Coke's overhaul is two years in the making. The brand ran focus groups with more than 10,000 people across the country and tested more than 30 potential flavor combinations, including several with tropical, citrus and botanical flavor notes. The process was driven by a desire to find varieties that match the affinity of younger consumers to bold flavors, evidenced by the rise of hoppy craft beers and spicy sauces. The strangest combination Coke tested might have been one combining tea flavors with spicy peppermint. Other flavors that did not make the cut include lemon lavender tea, mojito, oro blanco grapefruit, chili lime and watermelon jaleneno.

Diet Coke executives refer to the new can shape as "sleek." The 12-ounce cans, which are the same format now used by Coke-owned Dasani sparkling water, are meant to give Diet Coke a more contemporary feel. However, Diet Coke will also keep its traditional packaging formats like the shorter, fatter 12-ounce cans.

The 'High Line'

The new logo features a vertical stripe that Coke executives call a "High Line" that is meant to represent motion. It will be used across all communication, including digital and outdoors ads. Coke's in-house team designed the logo with help from a London-based agency called Kenyon Weston.

Executives declined to reveal what the overhaul cost or the size of the media budget. But the new look and flavors will get significant support, including a sizeable TV buy during the Winter Olympics. The new tagline replaces the "Get a Taste" line that debuted as part of a campaign from Droga5 that launched in 2014.

Coca-Cola Co. spent $46.5 million in measured media on Diet Coke in 2016, according to the latest full-year data from Kantar Media, down slightly from the $47.1 million spent in 2015.

Diet Coke went directly after baby boomers when it arrived on shelves in 1982. At the time, the demographic, covering people born between born between 1946 and 1964, was "getting 20 years older and 20 pounds heavier," Coke states in this history of the brand on its corporate blog. "We had an in-depth knowledge of our target consumer and the issue of weight in America," Jack Carew, who led the original Diet Coke project, states in the piece. "It all added up to a total impression of a better experience in the diet segment than the consumer had been getting."

The drink started out in a white can with red lettering. The tagline was "Just for the Taste of It." The first TV ad was filmed in Radio City Music Hall and spliced in footage of celebrities including Carol Channing and Bob Hope.

The brand rocketed out of the gate, becoming the No. 1 diet soft drink brand in the U.S. by the end of 1983, while displacing 7UP as the No. 3 soft drink of any kind by the end of 1984. In 2010, Diet Coke surpassed Pepsi as the nation's No. 2 soft drink, behind regular Coke.

But Diet Coke was soon hit by sales headwinds as the phrase "diet" fell out of favor with consumers who were increasingly drawn to products plugged as "natural." At the same time, artificial sweeteners drew more scrutiny and grocery aisles were filled with a dizzying array of beverage choices, including from many plucky start-up brands. By 2014, Diet Coke fell back to No. 3, where it remains today, according to Beverage-Digest.

Below, a Coca-Cola Co.-produced video showing how Diet Coke's look has changed over the years.