You've tried a lot of diets. You work out every day. But you're still carrying around those extra pounds. It seems like there should be something simple to do that's clinically proven to help you lose weight. In fact, there is, and it's surprisingly easy: keeping a food journal. A 2008 study from Kaiser Permanente's Center for Health Research showed that one of the best things you can do to lose weight is to write down what you eat.

Low cost, high return

This weight-loss plan costs little or nothing, and it doesn't involve suffering (unless you get writer's cramp). All you need is a pen and a notebook. If you want to get high tech, you'll find even more options. There are numerous online programs and apps to help you keep track of your food intake.

One popular program called Lose It lets you record what you eat, how many calories you've consumed and how much you exercise. It balances that data against your weight goals and tracks your progress. An online food journal is convenient since you can carry it with you wherever you go as a smartphone or tablet app.

But does it really work?

"Food journals are great if you go into it knowing that it's not an exact science," says licensed nutritionist Kathleen Putnam. "For some, it can be a lifesaver and great eye opener; for others, it becomes a quick road to insanity."

That's because you can get a little fixated about counting every calorie and end up feeling bad about it. Putnam says, "It can become a way to beat yourself up. If there's shame involved, people give up, or fill in what they think they should have eaten, rather than what they really ate—and that's not helpful."

But don't beat yourself up over what you eat—instead, learn from what you consume now, so that you can begin to change the way you eat. Positive results won't happen overnight, but the first step is being truthful with yourself.

Andie Petkus, a Portland, Oregon, photographer, never used to have a problem with her weight, but lately she's been feeling that she could stand to drop a few pounds. "I used Lose It on my iPhone, and I had good results the first time I tried it," she says. "I was surprised by how quickly the calories added up."

Petkus notes that having an accurate count of calories and a record of the hours she spent exercising made it easy to be consistent over time. "In my mind, I was exercising way more than I actually was," she says. "Now I can tell right away if I need to make up during the weekend for any mistakes I made during the week."

Finding your journal style

No matter what format you choose, whether it's a small spiral notebook, an app or an online diary, make sure it's handy at all times. As Putnam says, "Use a mode that's portable so you can carry it with you and you can record the food you're eating accurately." After all, it's hard to remember everything you eat and drink when several hours have gone by. Plus, we sometimes forget exactly what was on our plate when looking back on it later.

More tips for a successful food journal:

  • Record all of the food you eat. That includes regular meals, snacks and quick bites. Nuts are great for you, but even a handful of them can add up for your diet.
  • Keep track of what you drink. Many people consume a huge amount of extra calories from sodas, coffee drinks and juices.
  • Try to include exact serving sizes. There's a world of difference between a small serving of popcorn and a large one or between 8 ounces and 22 ounces of soda. And don't forget condiments: Butter, salad dressing, ketchup—they all add up, too.
  • Take note of where, when and how you eat. Are you snacking late at night? Do you overeat while watching TV? Do you always drink too many beers with certain friends? Write it down.

Putnam also suggests measuring and weighing your food for the first week or so. "We all underestimate how much we eat," she says. "After a week of measuring, most of us are ready to calculate accurately."

Along with writing down your meals and snacks, you may want to comment on hunger, mood, stress, energy level and anything else you think might be useful. In fact, the more information you provide, the better. "I highly recommend including a notes section," Putnam says. But it's your journal. Make it personal and you'll increase your chances for success—and for lasting weight loss.

Published on Jan. 23, 2012; updated on May 2, 2014.