The man who floated like a butterfly and stung like a bee has teamed up with a confectionery giant to market a range of low-calorie food and drinks.
US obesity rates for people aged six to 19 have more than tripled since 1980.
Health campaigners welcomed the move but say any programme to tackle obesity must address fundamental eating habits.
“Eat like champions, walk like kings,” proclaims a website promoting Muhammad Ali’s new range of reduced-calories food and drinks.
His company, known perhaps somewhat unappetisingly as Goat Foods, an acronym of “Greatest Of All Time”, plans to have the snacks in shops from early next year.
The range will include Shuffle, Jabs and Rumble, fruit-filled rolls shaped like boxing gloves or punchbags.
The foods, which are being developed by Mars, will be fortified with fibre and vitamins and have no more than 150 calories each.
“It is time to pass on the values, beliefs and principles that made me a champ to the next generation of champions,” Ali said in a statement.
It is not clear how involved the 64-year-old Ali, who suffers from Parkinson’s disease, will be in the project.
His fourth wife, Lonnie, told the New York Times that Ali was concerned about obesity in youngsters.
“What Muhammad is working on is his legacy. How are people going to remember him? Muhammad says we should all be in a race to do good,” she said.
The American Obesity Association said that in theory Goat food sounded good.
“But unless it ends up actually reducing the calories that the user consumes, it is not likely to have a benefit in terms of weight loss,” executive director Morgan Downey told the New York Times.
According to the association, approximately 30.3% of children aged 6 to 11 are overweight and 15.3% percent are obese.
For adolescents, aged 12 to 19 years , 30.4 % are overweight and 15.5% are obese.
Ali’s move into diet food comes two months after he sold the rights to his name and image for $50m (