What do the iVillage Food and Fitness Tracker, FitDay.com, NutraWatch.com and MyPyramidTracker.gov have in common? They're all online food journals that can help you keep track of what you eat, and they're an essential component of any successful weight loss program.

Lose weight

A study involving 2,000 weight loss program participants in Oregon showed that people who kept food records for at least five days each week lost more weight than folks less committed to writing down everything. Keeping a food journal was more predictive of weight loss than exercise habits. But food journals aren't just for weight loss; they're also an essential tool to maintain your new, lighter weight.

Conquer cravings

Keeping track of what, when, where and why you eat is one of the best ways to figure out what's causing your food cravings. Do you crave cookies every afternoon? Find yourself snacking in the evening while watching TV? Or maybe you reach for the ice cream when your kids are driving you up the wall. Writing down what's happening in your life helps identify the cause of cravings. Once you've figured out what's going on, it's much easier to make changes.

Portion control

Did I eat a small apple or a large one? Was that two tablespoons of peanut butter on my sandwich or three? Did I pour one cup of Cheerios into my bowl or two? The difference between a small and large apple is 55 calories, between two and three tablespoons of peanut butter is 8 fat grams and 94 calories, and between one or two cups of Cheerios is 111 calories. Err on the larger side all day, and you'll easily gain weight instead of lose it. If you write down what you eat, however, you'll pay more attention to your portion sizes.