Are you serious about sliming down? Do you feel like you're eating healthy but you can't seem to convince your scale? Are you having trouble reaching your diet goals?

Then it's time to start keeping a food journal.

A study from the August 2008 issue of the American Journal of Preventive Medicine shows that food diaries can have a tremendous impact on your weigh loss success. Within the study group, people who kept a food diary lost twice as much weight as those who didn't!

"People think twice about overeating or having unhealthy food if they have to write it down," says dietician Elizabeth Zemelman. "It keeps you accountable." That's why the founder of the Toronto-based Nutrition Group recommends that all of her clients who want to lose weight keep a strict record of what they're eating and drinking in a food journal.

You can use an old-fashioned pen and paper to jot down your daily eats, or use Canadian Living's new online food journal to help you keep track of exactly what you ate and drank for breakfast, lunch, dinner and snacks. This handy online tool also helps you track calories, carbs, fat and protein and shows the progress you’re making towards your goal.

Here's how it works:
• Write down, in detail, what you eat and drink for meals and snacks each day.

• Include portion sizes, such as two scoops of ice cream, one cup of carrots or one tablespoon of Italian dressing.

• Don't forget items like your daily double double, the fries you stole off you child's plate or the mini Snickers you snuck in before bed.

At the end of the day or week, look back at what you've entered into your food journal. You'll be surprised at how it affects you — you'll be proud of your healthy choices, you'll notice where you slipped up, but most importantly you'll be aware of exactly what you're eating. Often just a glance at your food journal will reveal where extra calories are coming from and what could be cut.

"People who graze and snack throughout the day may not realize what they're eating until it's down on paper," says Zemelman. "When you look at it at the end of the day you think, 'Oh my, maybe I did overeat.' Quite often we go through a client's journal and they say, 'Holy, I didn't realize I was doing that badly! I thought I was doing well.' They don't realize what they're putting in their mouths."

Judging by the trends among her own clients, Zemelman says people should watch out for too many high calorie junk food snacks and not enough fruits and veggies. Many people also overdo fruit juices and alcoholic beverages, which are full of extra calories and don't make you feel full.

"All those drinks contribute to excess calories," Zemelman warns. "You've got to be really careful with those."

Another tip she gives her clients, and probably the most important part of keeping a food journal: it doesn't pay to cheat.

"I tell my clients all the time that if you're cheating, you're just cheating yourself because you're the one who wants to get healthy. Write everything down."

Read more:
• 5 kitchen tools you need for healthy eating
• 6 ways to maximize your exercise
• 10 good-for-you eating strategies