Portion Size
Chester J. Zelasko, Ph.D. | February 4, 2003

Weight gain is not complicated: you take in more calories than you use in physical activity. If you do that frequently, you'll gain weight. Evidently, many Americans have been doing that in the past 25 years--over 64% of all U.S. adults are overweight (1). The official definition of overweight is a Body Mass Index (BMI) of 25-29.9. (To calculate your BMI, use our Body Mass Index Calculator.)

What is more alarming is that we're getting even fatter. Obesity is officially defined as a BMI greater than 30. More than 30% of all adults are now considered obese. To see how the rate of obesity has changed over the past 15 years, simply click on the link in Reference 2. This will take you to the website of the Centers for Disease Control and you can see a PowerPoint presentation of how obesity has increased since 1985 (2).

The question is, "Are we really eating more?" The answer is yes according to a recently published study (3). Researchers analyzed data from three prior nutritional surveys collected in 1977, 1989, and 1996. The subjects included over 63,000 men, women, and children two years old and older. Caloric consumption increased at every interval of time surveyed. People were eating almost 100 more calories in 1996 than in 1977. While that sounds like a small increase, an extra 100 calories per day can lead to a weight gain of 10 pounds in a year.

What's even more interesting is that portion sizes increased in both fast-food meals and meals eaten at home. Of all the foods examined, hamburgers eaten at home had the largest increase in calories--over 200 calories per burger. Salty snacks, soft drinks, french fries, and desserts all increased in calories and serving size. Only pizza remained about the same size.

What does this mean? We have to pay attention to the quantity of food that we eat not only at fast-food restaurants but also in the meals we prepare at home if we expect to reduce body weight. That means preparing smaller meals at home and either avoiding fast-food restaurants altogether or resisting the urge to supersize. While it may seem like a good deal at the time, the cost of disease far outweighs the low price of fast food.


  1. Flegal KM et al. Prevalence and trends in obesity among US adults, 1999-2000. JAMA 2002; 9;288(14):1723-7.
  2. www.cdc.gov/nccdphp/dnpa/obesity/trend/maps/
  3. Nielsen SJ and Popkin BM. Patterns and trends in food portion sizes, 1977-1998. JAMA 2003; 22;289(4):450-3.
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