I act like an adult most of the time. I do my taxes, get my oil changed and even own place settings. But when putting together my own meal, it's hard for me to resist eating a plateful of mashed potatoes (weakness No. 1) or having ice cream for dinner (weakness No. 2). To keep my portions in check (something even Estée Lauder spokesmodel Joan Smalls says is tough, but vital to looking good), I try to live by these rules:

-Half of everything you eat should be a fruit or vegetable.

-Treat meat as a side dish.

-Dedicate one quarter of your plate to whole grains.

Listen, I love a pound-zapping juice cleanse as much as the next yoga-mat-toting Californian, but the numbers on the back of those multicolored bottles don't lie: Juice packs a whole lot of sugar. If you're looking for a beverage with flavor, try water infused with lemon, cucumber, mint or ginger. By drinking a single glass of water before meals, you'll eat 75 fewer calories. If you drink it iced, you can raise your resting metabolism by about 50 calories a day, because (the theory goes) your body burns more calories trying to warm up the cold water.

To keep things easy, I like to freeze bits of mint in ice cubes. Just add chopped mint to an ice cube tray, pour water over it and pop it into the freezer.

Breakfast (or brunch, if you're in Los Angeles on a Sunday) really is the most important meal of the day. If you do one thing for your health, this is it. Skipping breakfast in lieu of a big mug of light and sweet coffee isn't only bad for your metabolism, it also makes you more likely to reach for high-glycemic, quick-energy foods come lunchtime. Experts say that indulging in foods like bread, white rice and pasta messes with the way your body burns fat. Instead of processing it normally, your body tries to regulate your blood sugar by getting it into storage ASAP -- as fat.

To avoid packing on saddlebags, steer clear of breakfast food like bagels, granola, sugary cereals and doughnuts. Instead, I grab a hard-boiled egg, plain Greek yogurt or oatmeal topped with blueberries and almonds -- it's a quick way to jump-start my day -- and keep on-track till bedtime.

Sleep seems like the opposite of a calorie-burning activity, right? Wrong. According to the American Dietetic Association, people who get fewer than six hours of sleep a night eat up to 300 calories more during the day. A bad night's sleep also lowers your patience and performance levels, and makes you more stressed-out. Since dream time is when your skin repairs itself, going without can do a number on your complexion as well.

If work worries are keeping me up for more than a few nights in a row, I hightail it to a butt-kicking workout class, like cardio dance or barre. The concentration and motivation required to complete a class usually tucker me out mentally and physically. By the end of the day, I'm so drained that I get the best sleep ever, waking up refreshed and ready for the day.

Aim for at least seven hours of shut-eye every night -- no excuses.

When I'm in a bad mood, the last thing I want to do is throw on workout clothes and break a sweat. But a recent study found that besides giving your body a boost, working out has above-the-neck benefits, too. Just 20 minutes of cardio causes a rush of endorphins and other feel-good chemicals that can make you happy up to 12 hours after. That's an hour of happiness for every minute and a half that you work out -- talk about a productive way to use your time. Plus, working out instantly boosts your self-esteem (and nothing is sexier than self-confidence).