A tried-and-true approach to losing weight the healthy way.

A tried-and-true approach to losing weight the healthy way.

Dieting used to be about what you couldn't eat: Fat. Carbohydrates. Anything that wasn't cabbage soup. But the latest science shows that when it comes to losing weight, what's most important isn't really what you're eating. It's how much.

In a study published last year in the New England Journal of Medicine, scientists assigned 811 overweight people to one of four weight-loss plans. All focused on heart-healthy foods and were designed to help people lose about 1.5 pounds per week (by providing 750 fewer calories per day than they were eating at the start of the study). The only differences between the diets were the relative proportions of fat, protein and carbohydrate. Each of the plans was either low in fat (20 percent of total calories) or high in fat (40 percent of total calories), average in protein (15 percent of total calories) or high in protein (25 percent of total calories). Across the four plans, carbohydrate ranged from 35 to 65 percent of total calories. After two years, the researchers checked to see which plan resulted in the biggest weight loss. It was a four-way tie. Participants lost about 9 pounds, on average, regardless of the mix of nutrients they were eating. Lesson learned: you can lose weight eating whatever you like so long as you limit calories.

There's the rub. We're living in a world where a cup of coffee-albeit a fancy one-can cost you 450 calories. A world where football-size burritos-that pack 1,000 calories-are the norm. Home-cooked meals can balloon out of control too. In a February 2009 report in the Annals of Internal Medicine, EatingWell Nutrition Advisor and Cornell University Professor Brian Wansink, Ph.D., compared recipes that appeared in both the original Joy of Cooking cookbook, published in 1936, and its most recent edition. He found that the average number of calories per serving jumped from 268 to 437 in the past 70 years. Why? Ingredient changes (usually adding more fat and sugar) and bigger portions.

The good news: we can return to "sane" serving sizes and still feel satisfied, with some smart planning. Having a 500-calorie dinner is one way. Of course, the rest of the day matters too. Most people can lose weight on 1,500 calories a day. If you want to be even more precise about cutting calories, a simple calculation will give you a daily calorie goal that can help you lose a healthy 1 to 2 pounds per week.

1. Find your magic number-like this: Multiply your current body weight by 12. (That's what you need to maintain your weight.) Then, subtract 500 from that number to lose a pound a week, 1,000 to lose two. (If your result is less than 1,200 calories, bump your goal up to that level. It's very difficult to meet your nutrient needs eating less than that.)

2. Make a plan. What will you eat for breakfast? For lunch? For snacks? According to one study published in Obesity Research, a menu plan for the whole day really does help you lose weight. Perhaps it's because it forces you to keep healthier foods on hand. In the study, people who had menu plans were more likely to keep nutritious low-calorie foods, such as fruits and vegetables, stocked at home than those who didn't. Planning ahead also helps to keep your eating on schedule: if you already know what you're having for lunch (and it's waiting for you in the fridge), you're less likely to let 6 or 7 hours pass without having something to eat-a situation that usually results in eating too much when you finally do sit down to a meal.

3. Avoid portion distortion. When you're trying to lose weight, learning to size up portions accurately is an important skill to master. According to Wansink's research, people tend to underestimate calorie intake by 20 to 40 percent. To combat "portion distortion," many weight-loss experts suggest using a kitchen scale or measuring cups to make sure you're getting the "right" number of calories-and not more. But whipping out measuring cups at meals may feel, well, obsessive. (And downright awkward at someone else's house.) There are other ways to keep an eye on portions. You might try the "Rule of Thumb" method, which uses your hand as a reference. If you're a relatively small-framed woman, 1 teaspoon equals the tip of your thumb (to the middle joint); 1 tablespoon is the size of your thumb and 1 cup is about the size of your fist. Obviously this isn't a precise way of portioning-and the margin of error is greater the bigger your hand is-but it'll work in a pinch. It might be a good technique to try when you're eating out or at a friend's house. When you're at home, you're using the same bowls and utensils over and over again. Why not find out how much they hold? Just once, measure out the amount of soup that your ladle holds. If it's 3/4 cup you'll know forever that two scoops equal a satisfying 11/2-cup serving. On the flipside, you can measure out a given portion of a particular favorite food and serve it in the dish you regularly use when you eat that food. Once you know that one serving of cereal reaches only halfway up your bowl, you'll know to stop there. (This is a good trick to try with wineglasses too.)

4. Write what you bite. Studies show that writing down everything you eat helps you lose weight. Buy a journal and jot things down. In your diary, include what you ate, how much and the calorie count. You might also note where you ate or how you felt. The more detailed your notes are, the more they help. One way to ensure that you don't exceed your "magic number" is to fill out your food diary before you eat anything. That's right: Write in what you're going to have for breakfast, for lunch, for snacks and for dinner-making sure it tallies up to your calorie goal or just a tad below (don't skimp).

January/February 2010