Start Recording
The crucial info to write down: the time you ate, what you ate, and how much you ate. Make a habit of jotting notes right after you eat. “If you wait until the end of the day, it’s too easy to leave things out,” warns Suzanne Farrell, R.D. Tracking your diet online? Remember to take paper with you to restaurants, so you can write down every ingredient and calculate its nutritional content afterward.

You may also want to invest in measuring cups — they’ll help you learn what a one-and-a-half-cup portion looks like (it’s a lot less than you think) — as well as a calorie-counter book and a calculator. Armed with these tools, you can track your calories like a nutritionist would.

Get Personal
Customize your diary so it reflects the info that’s most useful to you. For example, if you’re someone who eats whenever food is in front of you, create columns in your journal to rate how hungry you were before and afterward. If you snack your way through hard days, add a column to describe how you were feeling when you ate. Trying to figure out when you’re most drawn to junk food? Record where you were when you indulged and what was going on at the time. Also, if you’re trying to break a specific habit, like scarfing down ice cream at night, create a column for that, so you can give yourself a star for each day you resist the urge.

Be Honest
Include every single bite, lick, and taste (anything larger than a crumb counts). And don’t forget to keep track of your sips. Even the most diligent diarists often forget to include the glass of white wine they had at dinner (120 calories) and their 3 p.m. can of Coke (155 calories).

Experts suggest that, to help break bad habits, you record not only what you eat, but the circumstances that prompt you to eat. For example, maybe you indulge in more sweets at work because you sit close to the vending machine. Maybe you have a milkshake several times a week because you pass Wendy’s on the way home. Or maybe every time you worry about money, you retreat into the kitchen for chips.

When you begin to notice these patterns, you can figure out ways to change them. If the vending machine is a constant temptation, stock your desk drawers with fruit and granola bars. If you can’t resist a fast-food sign, MapQuest a new route to work. If you eat when you’re under pressure, steer clear of snacks and take a short walk instead (it’s a scientifically proven stress buster).

“I thought I ate a lot of vegetables — it seemed like I was constantly cooking spinach, broccoli, or Brussels sprouts,” says Maria Sanders, a 34-year-old mom from Orlando who’s been keeping a food diary for the past 18 months. “But looking back over a few weeks of my journal, I was surprised to realize that I was only eating veggies once or twice a week.” So she made salads a regular part of dinner and noticed that it helped her eat less of her entrée. Her analysis and follow-up action paid off: She’s lost more than 27 pounds.
A balanced diet is the key to weight loss, says Suzanne Farrell, R.D.”Whole grains, low-fat dairy, green vegetables, orange veggies, beans, nuts — science shows that we need to eat these regularly to reach a healthy body weight. So when I flip through my clients’ journals, I always look for what I’m not seeing.”

Make a mental checklist of what you ate yesterday. Sure, you can probably remember breakfast, lunch, and dinner — but what about that mini Snickers you snatched from your coworker’s stash? Or that spoonful of mashed potatoes you took off your husband’s plate?

It’s easy to overlook bites, licks, and tastes (known as “BLTs” to professionals). But that’s a huge mistake — there are 25 calories, on average, in each mouthful. Translation: Six little bites a day add up to around 15 extra pounds a year.

“I remember one client who was keeping a diary and couldn’t understand why she wasn’t losing weight,” says Bethany Thayer, R.D., spokesperson for the American Dietetic Association. “We were discussing the problem when she took out a peppermint. I asked her how many she ate every day, and she said, ‘A bag.’ They’re nine calories each, but the whole bag is several hundred.”

Writing everything down can also help you make smarter food choices. If you often order a Starbucks Grande Dulce de Leche Latte, entering the data will bring you face-to-face with the fact that your beloved drink packs 440 calories, versus 23 calories for the same-size regular coffee with milk.

Americans typically underestimate their daily intake by about 25 percent, reports nutritionist Carrie Latt Wiatt, author of Portion Savvy. The situation gets even more complicated when you eat out. In a 2006 study led by Cornell University, 105 diners in fast-food restaurants were asked how many calories were in their orders. For the small items, almost everyone guessed correctly; for the larger orders, the diners underestimated the calories by a whopping 38 percent. It may be an issue of perception, says study author Brian Wansink, Ph.D. The larger the quantity, the harder it is to make an accurate guess — the same is true for distances and heights.

Even professionals can be tricked by hefty portion sizes. When an NYU researcher asked 200 dietitians to estimate the calorie count of four popular restaurant dishes, the experts lowballed the number for each by a whopping 250 to 700 calories.

So stop assuming and start calculating. A good manual, like the classic Calorie King Fat & Carbohydrate Counter, makes it easy by giving you the calorie counts and fat grams for a huge number of foods.