Still, not everyone feels the same energy jolt from a given beverage. “There are genetic differences in how people respond,” Haskell-Ramsay says. She, for one, avoids coffee. “It’s too stimulatory for me,” she says. That is, unless she’s desperate. “I was at a conference once, and the tea was terrible. By day four or five, I was so caffeine-deprived, I finally bit the bullet and ordered a cappuccino.”