For entrepreneurs, eating isn't just about satisfying hunger. So say the growing ranks of nutrition experts who specialize in fine-tuning the metabolic performance of business leaders. "You're like an athlete in the workplace," says Richard Chaifetz, CEO of ComPsych, a Chicago-based provider of corporate wellness and employee-assistance programs. "So you should eat like an athlete."

At the very least, that means lots of lean protein, fruits and vegetables, and complex carbohydrates; no processed foods; and minimal white flour and sugar. But when you spend all day confronting challenging mental tasks, the brain's nutritional demands are greater.

For example, have you ever worked so hard that it felt as though your brain were on fire? It sort of was, says Patti Milligan, director of nutrition at Tignum, a consultancy that helps businesses boost employee performance through holistic wellness programs. "You produce lots of oxidants in the brain when you're working," she says. "Foods that are high in antioxidants--berries, beans, apples, tea--act like flame retardants."

And don't forget water. "The brain is 70 to 80 percent water," Milligan says. "When it's metabolically active 10 to 12 hours a day, removing metabolic waste from the brain requires optimal hydration." She suggests "super-hydrating" with two cups at the beginning of the day and avoiding "dehydrators," like processed sugary foods, high doses of caffeine, and soda. And watch out for "brain fog," which can be evidence that you need to hydrate.

Speaking of caffeine, "coffee depletes serotonin, which contributes to a sense of well-being," says Barbara Mendez, a New York City nutrition consultant who works with many business clients. "If you have it on an empty stomach, that quick delivery to the bloodstream leads to more anxiety and stress." So save the coffee for midafternoon, when your hormonal and