Of course you know that protein's essential for a slimmer you and essential for losing belly fat—you couldn't have made it through the Paleo and South Beach crazes without hearing all about it. But here's why protein really needs to play a prime roll on your plate: "Your body starts to produce more insulin as you age, since your muscle and fat cells aren't responding to it properly," explains Louis Aronne, MD, Director of the Obesity Clinic at Cornell. And insulin promotes fat storage, especially around your belly (yippee!). A diet high in protein may protect you against insulin resistance, Aronne says. One easy way to up your intake is to add Organic Whey Protein to your smoothies, meals, or snacks.
Doing crunches until the cows come home? Stop it! When you're down to your final inches of belly fat, the dreaded crunch won't be the exercise that finally reveals your six-pack. "You can't spot reduce," Jill says. Instead, she suggests doing functional exercises that use the muscles in your core—abdominals, back, pelvic, obliques—as well as other body parts. "These exercises use more muscles, so there is a higher rate of calorie burn while you are doing them," she says. Planks are her favorite functional exercise—they activate not just your core muscles but also your arm, leg, and butt muscles.
Watch: 5 Best Moves for Flatter Abs