1. You'll get a reality check about how many calories you consume. continued...
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. Or try nutritiondata.com, which also lists the stats for many foods.
2. You'll cut back on between-meal munching.
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.
3. You'll discover where your diet detours.
"I thought I ate a lot of vegetables — it seemed like I was constantly cooking spinach, broccoli, or Brussels sprouts," says Melissa Smith, a 32-year-old mom from Omaha 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.