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.