You know the drill. Your 5 p.m. Friday happy hour turns in to a three-day bender when you're hanging out with this party lady. A hefty amount of two-for-one margs, 3 a.m. Taco Bell runs and a couple of day-drinking episodes later, the details are hazy, but one thing is clear: Your diet is as completely wrecked as you were.

While it's hard to say no to cocktails and conversation when you need to blow off steam, partying habits do more harm than good. Studies show that alcohol actually stimulates the appetite, meaning you're going to pile on even more calories than the ones you're imbibing. The next time your partying friend suggests a get-together, go somewhere where alcohol and food aren't the main attraction, says Conason. Time to dust off your bowling shoes (for an activity that burns 115 calories an hour!) and brush up on your pool skills.

Simpson offers this tip for nights out: "Be the first to order, and get the healthiest drink -- a spritzer, for example. Order a water and keep it in your other hand. It'll take you twice as long to finish your drinks, and you won't have another hand to accept a new one."

You haven't lived until you've tried this new restaurant, she says, at least once a month. She waxes poetic on crookies, cronuts, wonuts and $30 gourmet ramen burgers, and she'll be damned if you die before you try them all with her. Your foodie friend drags you to restaurant openings on the reg, and her foodie nature insists that experiencing the finer (read: fatter) things in life is way more important than watching what you eat.

Set boundaries with your foodie friend, suggests Conason. Make it clear what you're willing to eat and what you're not willing to eat. Simpson says preparing for your night out by snacking healthily on things like nuts and fruit beforehand can help you resist whatever of-the-minute concoction the foodie is pushing your way.

Alternatively, try bartering your activities with your friend. For every restaurant opening you attend with her, she has to go to a workout class or raw restaurant with you. When she's huffing and puffing her way through cardio barre for the third time in a week, or choking down cold green pea soup, she'll get the picture that not everyone has to love the same things.

A close cousin to the foodie, the over-orderer thinks of eating out as the perfect time to indulge. Buttered biscuits, spinach-artichoke dip and oysters with three kinds of dipping sauces to start, red wine all around, and multiple courses before you polish things off with a few samples from the decadent dessert menu is just a standard night out with this buddy. Before you know it, your stomach is beyond full (and your wallet is pretty empty after splitting the check).