U.S. Adults Eating More—& More Often

Jul 14, 2011

Do your overweight and obese clients have trouble losing weight and keeping it off? Part of the problem may be how frequently they eat. Over the past 30 years U.S. adults have been eating larger portions and eating more often, according to a new study by University of North Carolina at Chapel Hill researchers. Their findings help illustrate how Americans’ eating habits are contributing to the country’s obesity epidemic.

“First, the food industry started ‘supersizing’ our portions, then snacking occasions increased and we were convinced we needed to drink constantly to be hydrated,” said Barry Popkin, PhD, the study’s senior author and W.R. Kenan Jr. Distinguished Professor of Nutrition at the UNC Gillings School of Global Public Health.

The study is believed to be the first to examine the combined contribution of changes in three key factors—portion sizes, food energy density and eating frequency—on people’s total calorie consumption. The findings appeared in the June 2011 issue of PLoS Medicine.

Study Findings

In the study, Popkin and Kiyah Duffey, PhD, postdoctoral fellow at the UNC Interdisciplinary Obesity Center, analyzed U.S. adults’ dietary intakes over four separate 24-hour periods, based on surveys taken in 1977–1978, 1989–1991, 1994–1998 and 2003–2006. The researchers found that the average daily total energy intake, measured in calories (kcal), increased from 1,803 kcal in 1977–1978 to 2,374 kcal in 2003–2006, an increase of about 570 kcal.

Increases in the number of eating occasions (meals and snacks) and in the portion sizes of foods and beverages over the past 30 years accounted for most of the change. Changes in the energy density of foods and beverages (i.e., the number of calories in a specific amount of an item) contributed a slight decrease in daily total energy intake over the 30-year study period.

In daily total energy intake, portion size accounted for an annual increase of nearly 15 kcal between 1977–1978 and 1989–1991, whereas changes in the number of eating occasions accounted for an increase of just 4 kcal per year. Then, between 1994–1998 and 2003–2006, changes in the number of eating occasions accounted for an annual increase in daily total energy intake of 39 kcal, whereas changes in portion size accounted for an annual decrease of 1 kcal. The average energy density of foods and beverages remained steady between 1977–1978 and 1989–1991, then declined slightly between 1989–1991 and 1994–1998.

A Way to Prevent Obesity

As participants in the surveys may have under- or over-reported the amount of food they consumed, the findings may not be completely accurate, Popkin noted. “Still, these findings suggest that efforts to prevent obesity among adults in the U.S should focus on reducing the number of meals and snacks people consume during the day and reducing portion size as a way to reduce the energy imbalance caused by recent increases in energy intake,” he said. “I would speculate that the same advice would apply to other developed countries.”

For more information, see www.plosmedicine.org/article/info%3Adoi%2F10.1371%2Fjournal.pmed.1001050.

IDEA Fit Tips, Volume 9, Issue 8

© 2011 by IDEA Health & Fitness Inc. All rights reserved. Reproduction without permission is strictly prohibited.


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  • Howard Yoshino

    As a Type 2 diabetic, I too eat 5-6 small healthy meals a day. I consume a meal every 2-3 hours. It prevents my hypoglycemia from kicking in. In the process I've been able to drop undesired weight (body fat) as well as control my diabetes. Drinking at least 64 fluid ounces of water a day is very important too.
    Commented Aug 15, 2012
  • Pamela Amos-Rose

    I agree with Stephanie, there is an overconsumption of meat, processed and packaged foods.
    Commented Aug 21, 2011

    A calorie is a calorie. Some are better then others. Portion control and eating good food in smaller portions thoughout the day works for me and I am extremely active.
    Commented Aug 21, 2011
  • Sue D'Alonzo

    I think our definition of "food" has changed. People are eating processed food and fast foods more than ever. Look at our grocery stores- the processed, packaged foods are taking over. If we would eat wholesome foods, whole fruits and real veggies we wouldn't be having this discussion! Sugar, fat and salt are taking over.
    Commented Aug 07, 2011
  • Sarah Parker

    Fabio: you are quite right, especially when frequent meals/snacks are very large or calorie dense. I eat 5-6 small meals a day, and this works for me. I am very active, so I need to eat frequently or I become famished. But because of GI issues, I cannot eat large quantities/calories in one sitting. Stephanie: I think it is important to find what meal frequency works well for your body and activity level
    Commented Aug 04, 2011
  • Karyn Edison

    I say, plan three balanced meals. Divide them in half to eat six times per day. By the end of the day you will meet nutritional and frequency standards.
    Commented Aug 04, 2011
  • Fabio Comana

    The information shared can be misleading. While we recognize the benefits of more frequent meals during the day, the convent here is that unless total caloric intake is monitored, more frequent meals/snacks can be problematic. More frequent, smaller meals that demonstrate caloric control is what you should pursue.
    Commented Aug 04, 2011
  • Stephanie Rasband

    It can be very confusing trying to keep up with the advice on meal frequency, size and weight loss. I always heard that snacking was what led to an uptick in Leptin so 3 meals, lower GI and no snacks. In recent years it is all 5 small meals or 3 and two snacks. What is the scientific truth?
    Commented Aug 04, 2011
  • Eliana Ghen

    So true, unfortunately in the USA!
    Commented Aug 04, 2011

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