The caffeine in your morning cup of java is powerful stuff. "Sometimes it's too powerful," says Amy Goodson, a dietician for Ben Hogan Sports Medicine. "Unless you're used to it, caffeine can induce a jittery feeling and headache symptoms—a bad combination when you're standing over a breaking three-footer."
But it's not all bad news, Starbucks addicts. Coffee gives your central nervous system a jolt, providing a very real energy kick. "Just don't expect it to last for 18 holes," Goodson warns.
If you like a lot of coffee, Mr. Venti, then pair it with a meal heavy in protein, carbs and healthy fat—such as a veggie omelet with toast—to stabilize your blood-sugar levels.
"Be smart," Goodson advises. "If you're not a regular consumer of coffee, don't drink it on the course." And if you are? "You'll probably feel and score better by feeding your fix."