It was Giorgio Armani's obsession with health that led to his brush with death. For 10 days in May 2009, Armani, one of the most influential fashion designers and entrepreneurs of our time, lay in a hospital bed with what he describes as "a very serious" case of hepatitis. The cause of his illness wasn't the stress that comes from juggling a global empire of clothes, accessories, furniture, cosmetics and real estate. It was the supplements. Then 75 years old, he was drinking them every morning in a small glass as he hit the gym. "My doctor told me: Get rid of all this shit you're drinking," Armani recalls.

Armani won't say exactly what he was taking, only that the substance poisoned his liver. Why he was taking it, however, is clear: The house Armani has built is a reflection of himself—the trim, toned, tanned and T-shirted figure that is synonymous with the brand—and he wants to secure a long life for both.

Few people in the fashion world are as entwined with their brands. In most companies, a creative director designs and an executive manages. Armani does both. Many important designers, including Karl Lagerfeld and Marc Jacobs, work under contract for brands that aren't their own. Armani hasn't designed for anyone else in more than 30 years. Most houses are owned by large conglomerates, and for those that still belong to their founding families, ownership is usually shared. Armani owns 100 percent of Giorgio Armani SpA.

Armani takes full responsibility, and credit, for anything that bears his name. At a meeting last year about a new Armani-branded hotel in Marrakech—hotels are the designer's latest big venture—Armani sparred with the architect Jean-Michel Gathy over the layout of the rooms. "This bathroom is too big. It's a bathroom with a house on the side," Armani said in French. "I tell you this is a beautiful room. You can walk around naked, and no one will see you," insisted Gathy. "You don't need to walk around naked every day," snapped Armani. "This is too structured, too busy. I want simplicity, simplicity." The layout has since been changed.

Gathy says that when he was negotiating his contract to design the hotel, Armani did not want him to be publicly recognized as the architect. Gathy, who has designed many luxury hotels worldwide, had to persist for several months before Armani backed down. (Armani did not comment on Gathy's contract.) "He's a control freak," says Gathy. "But that's what it's like to work with Armani. He's the old man, the icon, the alpha male in the room. And that's no problem."