This diet bully is often disguised as a benevolent baker. She's always sending out an office email with the subject, "Treats in the Kitchen." In her spare time, she trolls Pinterest for new, impossibly difficult confectionary challenges, and she never misses a chance to unload 24 cupcakes on you for your birthday. Or Valentine's Day. Or Friday.

This person's heart is probably in the right place -- food is often a way to communicate or find common ground, so it could be her way of forging a friendship, explains Conason. If it's a coworker, leave the treats in the break room and ask her to go on an after-lunch walk instead (research shows a 15-minute walk can curb cravings, meaning you won't make a beeline for the treats when you get back to the office). If it's a friend, make sure she's aware that you're watching what you eat. Mentioning something about how much easier it is to resist sweets when they're out of sight will keep her from loading you down with sweets. Plus, if she knows you're eating healthier, she may try to do the same, which will make your goal that much easier. Researchers call it positive peer pressure -- when friends mirror each other's eating habits. Just make sure you're the one setting the trend.

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.