The summer's over, and with it, any need to show up in public in a bathing suit. But before you layer on the sweaters -- and the pounds they can hide -- check out this advice from Daphne Oz (yes, the daughter of Dr. Oz, RealAge medical advisor and Oprah health expert), who's just followed her first book, The Dorm Room Diet, with a down-to-earth sequel: The Dorm Room Diet Planner. After years of adolescent struggles with as much as 30 extra pounds, Daphne started to lose weight in high school -- and went to college determined: She not only avoided the loathed freshman 15 but lost 10 pounds. Talk about A+ work! Here are her top stay-slim tips, no matter what your age:

Drink half your body weight in ounces of water daily, including one glass before every meal.

Avoid emotional eating. The next time you reach for that cookie, ask yourself whether you're being prompted by stress, hurt, depression, boredom, or even joy. The purpose of eating is to fuel your body, not temper your feelings.

Always have breakfast. It gives energy to your body and brain, and keeps you from going into starvation mode and binge-eating later.

Schedule time to eat. Plan on three meals and two fruit or veggie snacks every day. Look at your schedule for the day and block out windows of time to eat; "not enough time" is not an excuse.

Count to your age before you "cheat." Anytime you find you are about to eat something that's not healthy, count to your age. If you still want a bit after your countdown, feel free; you've made a conscious decision to indulge.

Ditch the defeatist attitude. Everyone falls off the bandwagon sometimes. The important thing is to get back on. So when you succumb to that late-night bowl of ice cream, don't think, "Well, I've already been bad, so I might as well finish the rest of the carton." Instead, enjoy the occasional indulgence and resume your resolve.

Get off the couch. A daily exercise routine would be ideal. But even walking up a few flights of stairs for a face-to-face conversation is better than instant-messaging.

Avoid processed snacks. Always try to have a piece of fruit rather than processed snack foods, especially late at night. If fruit alone doesn't cut it, try adding some peanut butter. If you need a sugar fix, nuke a handful of dark chocolate chips in the microwave for a few seconds and dip your fruit into that.

Sounds simple. It is. And Daphne's proof that it works.