The prevalence of obesity in the United States increased from 14.5% in 1971 to 30.9% in 1999. This substantial increase is attributable, at least in part, to changes in dietary habits: Americans are eating more.

In this “supersized” culture, it appears that portion sizes have gotten bigger. One study has shown that the most commonly available food portions exceed the US Department of Agriculture (USDA) standard portion sizes, and that most foods are available in larger portion sizes than they were in the 1970s. Another study showed that portion sizes of meat have increased, but did not look at other foods.

A study published in the January 22/29 Journal of the American Medical Association, providing the first systematic review of eating patterns among Americans, finds that portion sizes have indeed increased between 1977 and 1998.

About the Study

Scientists from the University of North Carolina at Chapel Hill analyzed nationally representative dietary intake data from 63,380 people aged two and older. The data was collected from three surveys, conducted in 1977, 1989, and 1996.

In addition to quantity of food consumption, participants specified whether the food was part of a meal or a snack, and whether the food was obtained in a fast food establishment, a restaurant, or in the home.

The foods were broken down into categories that were selected by researchers because combined, they represented the biggest change in caloric intake between 1977 and 1996. Specifically, these categories, which included salty snacks, hamburgers, and soda, comprised 18.1% of all calories consumed in 1977-78 and 27.7% of all calories consumed in 1994-96.

The Findings

The researchers found that fast food establishments served the biggest portions; the smallest portion sizes were found in restaurants. Portion sizes served at home, which fell in between, saw a large increase between 1977 and 1996.

Food portion sizes increased for all foods (except pizza) in all locations between 1977 and 1996. The following shows the increase in portion size and calories consumed from 1977 to 1996 for specific foods and food categories.

  • Salty snacks (including crackers, potato chips, pretzels, puffed rice cakes, and popcorn): 93 calories (from 1.0 to 1.6 oz)
  • Soft drinks: 49 calories (from 13.1 to 19.9 fl oz)
  • Hamburgers: 97 calories (from 5.7 to 7.0 oz)
  • French fries: 68 calories (from 3.1 to 3.6 oz)
  • Mexican food (including burritos, enchiladas, tacos, and tostadas): 133 calories (from 178.6 to 226.8 g)

How Does This Affect You?

This study confirms the long-held suspicion that portion size has increased over the last two decades. As the study highlights, larger portions are not only found in fast food restaurants—larger portions have become the norm even in our homes. These findings are particularly striking given the fact that only ten additional, unexpended calories per day result in an extra pound of weight per year.

As the authors of the study point out, if we are to successfully combat the growing epidemic of obesity, we will have control not only what we eat, but how much we eat.

The first step in portion control is being able to identify what constitutes a “serving”:

  • A deck of playing cards = one serving (three ounces) of meat, poultry, or fish (can also use the palm of a woman's hand or a computer mouse).
  • Half a baseball = one serving (one-half cup) of fruit, vegetables, pasta, or rice (can also use a small fist).
  • Your thumb = one serving (one ounce) of cheese.
  • A small hand holding a tennis ball = one serving (one cup) of yogurt or chopped fresh greens.

The American Institute for Cancer Research (AICR) recommends the following tips to control food portions:

When at home:

  • Take time to "eyeball" the serving sizes of your favorite foods (using some of the models listed above).
  • Measure out single servings onto your plates and bowls, and remember what they look like.
  • Avoid serving food "family style." Serve up plates with appropriate portions in the kitchen, and don't go back for seconds.
  • Never eat out of the bag or carton.

When in restaurants:

  • Ask for half or smaller portions. (Don't worry if it doesn't seem cost-effective; it's worth it.)
  • Eyeball your appropriate portion, set the rest aside, and ask for a doggie bag right away.