5. A health halo on fast food restaurants.

Eating at a restaurant that bills itself as better for you may backfire if you aren’t careful about what you order. According to a recent study from Cornell University in Ithaca, N.Y., people who go to a fast-food restaurant with a healthy image (think Subway) often end up eating more calories than those who go to traditional fast-food establishments like McDonalds. “When people think a type of food is good for them, they think that it can do no wrong, so they don’t pay attention to their portion sizes and don’t check to see how many calories they’re consuming,” explains Blatner, author of The Flexitarian Diet (McGraw Hill, 2008).

Slimming solution: Do your homework. “Before you go to a restaurant, visit its website to find the nutrition information for its items,” recommends Blatner. “That way, you can make an informed decision when you arrive. ”Healthy choices should have approximately 500 calories and less than 6 grams of saturated fat.

6. A “free” day.

Giving yourself a “free” day on the weekend to eat whatever you want isn’t an effective strategy, although it’s often touted as a way to keep your diet from being too restrictive. “People tend to overeat and make very poor food choices on the ‘cheat day’ and they feel deprived the rest of the week as a result,” says Beck.

In fact, researchers at the National Weight Control Registry found that people who shed pounds were more likely to regain them after a year if they allowed themselves to eat more on weekends and holidays.

Slimming solution: A little wiggle room in each day’s calorie count can keep you from feeing deprived. “Give yourself 150 bonus calories a day,” advises Beck. “That’s enough to satisfy cravings, but not so much that you’ll blow your healthy eating habits.”