Portion Distortion in Home Kitchens

It's not just fast-food restaurants that have supersized the way Americans eat. Cookbooks share the blame.

So-called portion distortion, the trend of eating larger and larger servings, is as much a problem with recipes as it is restaurants, and it has been going on even longer, according to a study published this week in the Annals of Internal Medicine.

The study, which looked at how classic recipes have changed during the past 70 years, found a nearly 40 percent increase in calories per serving for nearly every recipe reviewed, about an extra 77 calories.

The study identified the trend in numerous cookbooks, but it focused on American kitchen icon "Joy of Cooking," first published during the 1930s and regularly updated with new editions since then, most recently in 2006.

Of the 18 recipes published in all seven editions, 17 increased in calories per serving. That can be attributed partly to a jump in total calories per recipe (about 567 calories) and also to larger portion sizes.

Only the chili con carne recipe remained unchanged through the years. The chicken gumbo, however, went from making 14 servings at 228 calories each in the 1936 edition, to making 10 servings at 576 calories each in the 2006 version.

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