Jumping into the ring with Weight Watchers and the South Beach Diet is the newest eat-healthy contender, Muhammad Ali.

In a delicate dance of legend, marketing and money, Mr. Ali plans to introduce reduced-calorie foods and beverages for young adults, evoking his status as a three-time heavyweight boxing champion and American icon.

The first products to roll out inconvenience stores early in 2007 will be packaged snacks with names like Rumble, Shuffle and Jabs — fruit-laden rolls and finger foods baked into vaguely signature shapes like boxing gloves and punching bags. Some flavors, like barbecued chicken and Buffalo wings, are a twist on snack classics, while others, like sweet corn and coleslaw, evoke the farmer’s market.

The new line has the lofty aim of fighting youth obesity, with no snack containing more than 150 calories. Each is fortified with vitamins and fiber, said Edward Rapp, a senior member of Mr. Ali’s new company, GOATFood and Beverage (GOAT being an acronym for — what else?— Greatest of All Time).

Whether a line of snacks, no matter how nutritious or low in calories, cholesterol and fat, can dissuade many young Americans from disastrous and deeply ingrained eating habits remains to be seen, some nutritionists and obesity experts said. “People are often suspicious of healthier versions of food,” said Kelly D. Brownell, founder and director of the Rudd Center for Food Policy and Obesity at Yale. “They assume that it won’t taste good.”

The new venture comes at a time when business interests are increasingly looking to sports stars, like soccer’s Pelé, to add magic to product lines. The global Pelé business, which includes endorsements for MasterCard, Nokia and Pepsi-Cola, could earn $30 million next year, and George Foreman has earned more than $137 million for promoting the grill that bears his name.

Mr. Ali, who is battling Parkinson’s syndrome, is considering how history will treat him, his wife, Lonnie, said.

“What Muhammad is working on is his legacy,” said Ms. Ali, who often acts as his spokeswoman. “How are people going to remember him? Muhammad says that we should all be in a race to do good.”

Yet the process of leveraging Mr. Ali’s image into a line of snacks is fraught with obvious dangers. Add to this the complications of working with a man who has difficulty expressing himself and barely speaks above a whisper. The snacks signal the beginning of a more ambitious line of foods and beverages to follow. While none of the principals of GOAT would discuss what Mr. Ali stands to earn from his interests, Jack W. Plunkett, a food industry analyst, speculated that he could easily earn $1.5 million a year.

Mr. Plunkett, chief executive of Plunkett Research, a market research firm in Houston, said nutritionally enhanced foods were increasingly good sellers. He also noted that Mars Inc., a multibillion-dollar company that is developing GOAT products with Mr. Ali and Peter Arnell, chairman of the Arnell Group, would be involved only if it believed that the foods would be major sellers, earning $50 million to $100 million a year.

In arrangements involving food products, Mr. Plunkett said, celebrities are usually cut in for 3 percent of sales.

Mr. Arnell has been the catalyst for the new company, but he said that Mr. Ali, a longtime friend, was far from a passive player. He said he approached Mr. Ali two years ago, when he learned that Mars had been working on technologies to develop low-fat yet tasty food for young adults. Mars, he said, had no real concept of how to brand the foods, but Mr. Arnell did, bringing what he called the “aspirational currency” of Mr. Ali to the new line.

He said Mr. Ali had approved every aspect of the creation and marketing. At times, he noted, Mr. Ali would get “pent up with frustration in his inability to articulate in perfect words” in a meeting. “He would push himself to the limit when he felt I or someone wasn’t understanding,” Mr. Arnell recalled. “He would whisper stuff in my ear, ‘This isn’t right, no.”

The percentage of people age 6 to 19 who are overweight in the United States has more than tripled since 1980, according to the National Center for Health Statistics. Thirty percent of adults 20 years of age and older, more than 60 million people, are obese.

Mr. Arnell, 48, said that by changing his own eating habits, he shed about 250 of his almost 400 pounds in 30 months.

GOAT’s Shuffle snack, a mix of shapes, colors and textures, has only 35 fat calories compared with 111 for a comparable portion of potato chips, and reduced sodium. But like potato chips, the snacks beckon to be eaten in handfuls that could easily exceed their meager serving sizes of 1.06, 1.23 and 1.4 ounces.

Morgan Downey, executive director of the American Obesity Association, a health education and advocacy group in Washington, said that in theory, the GOAT food sounded good. “But unless it ends up actually reducing the calories that the user consumes,” Mr. Downey said, “it is not likely to have a benefit in terms of weight loss.”

The deal is the first brand creation for Mr. Ali, though he has lent his name to an Adidas line of shoes featuring famous athletes, and he allowed his image to be used in an Apple computer campaign. It follows an announcement in April that the entertainment company CKX had paid $50 million for an 80 percent stake in Mr. Ali’s name, image and likeness.

Slightly stooped, Mr. Ali entered a conference room earlier this month in the 90,000-square-foot Muhammad Ali Center overlooking Louisville. He barely spoke. When he managed to, it was hardly more than a whisper. Dressed in a dark suit, crisp white shirt and patterned tie, he listened to Mr. Arnell’s presentation regarding the food's start-up, which is scheduled for Jan. 17, Mr. Ali’s 65th birthday. Mr. Ali sampled some foods and followed Mr. Arnell’s remarks while turning the pages of an oversized book of new marketing materials.

He showed concern over a draft that suggested that his “greatest fight” would be against youth obesity. Ms. Ali pointed out to Mr. Arnell that Mr. Ali considered Parkinson’s his greatest fight. The passage was changed.

Mr. Rapp said the new foods were being engineered to fit into the “grazing” behavior of 16- to 24-year olds. The foods are intended to be eaten throughout the day, in seven “rounds,” he said. Round five, he said, is late in the day when people may need a vitamin-rich pick-me-up.

In the end, the foods must be tasty. “It doesn’t matter how good it is for them if they won't eat it,” Mr. Rapp said.