Shutterstock. Set (and write down) reasonable expectations for what you plan to achieve during your challenge. "You can absolutely make a difference in 10 days," says Brooke Alpert, RD, a dietitian in New York City and the author of The Diet Detox, but don't expect to shed 20 pounds a la The Biggest Loser. "While actual weight loss will be around three to four pounds, you can really notice the ...