Enticing packaging and nutrition labels with words you can hardly pronounce can make it hard to make healthy choices in the supermarket.

Janis Jibrin, who is a registered dietician and author of Good Housekeeping's new book, "The Supermarket Diet," has some tips on how to buy the right foods.

"Fiber is very important for people trying to lose weight because it makes you feel fuller longer. Cereals vary greatly in the amount of fiber they contain. So the rule of thumb is per 100 calories, you want at least 5 grams of fiber and 5 grams of sugar or less," Jibrin said.

Jibrin also recommends whole-grain foods, but said that it is not always easy to tell whether you are buying the real thing.

"The words multi grain do not always mean they are whole grain. Unbleached wheat flour, that sounds great, but it is not a whole grain," Jibrin said. "Light means it is light in flavor and light in color. (There's) no difference in calories, no difference in fat. So once again, you have to go to the nutrition-facts panel. Check the calories, check the serving size, check the fat to make sure you're really getting a light product," Jibrin said.

She also recommends buying whole fruits rather than fruit juices. You can feel fuller on fewer calories with the actual fruit.

"The Supermarket Diet" is the first diet book Good Housekeeping has published. It also includes exercise advice.