It s common knowledge that obesity has become an important part of American health care costs, as well as impairing the quality of life for up to a third of the population. And experts have been concerned that obesity rates have increased all age groups in the last few decades. Both energy intake and expenditure are key aspects of body weight changes. Thus a recent report in the American Journal of Clinical Nutrition provides some hope that the obesity epidemic is beginning to wane.
Researchers from the CDC examined trends in energy intake by adults as provided by the National Nutrition and Health Examination (NHANES) surveys between 1971-75 and 2009-2010. They analyzed trends in energy intake by adults between the ages of 20 and 74 years in the nine NHANES surveys performed during that time period.
NHANES surveys include personal, in-home interviews with participants, followed by direct measurements (such as body weight and height) of those who are willing to be further involved.
Analysis of energy intake by nearly 64,000 participants showed that between the survey in 1971-75 and that done in 2003-04, energy intake increased from 1955 calories per day to 2269 calories per day. It then declined, so that by the 2009-10 survey the average energy intake was 2195 calories per day. These intake trends were highly statistically significant.
In addition, the investigators also noted that adults between the ages of 20 to 39 years, those with BMI under 25 (normal) and BMI over 30 (obese), and both men and women had reduced their energy intake significantly between the 1999-2000 and the 2009-2010 NHANES surveys.
Over the course of the analyzed surveys, the researchers found that the percentage of calories consumed from carbohydrates (sugars and starches) increased between the 1976-80 and 1988-94, while that from fat decreased slightly. Protein intake remained constant. They remarked that, Future research into behaviors that guide energy intake may help to clarify the underlying dynamics of the observed trends in energy intake.
ACSH s Dr. Ruth Kava agrees with the authors that More information is needed to clarify the importance of such factors as frequency of eating out, changes in portion size and changes in dietary pattern. In addition, we need to better understand how to motivate individuals to make the appropriate changes in their intake so that we can continue the trend of decreasing energy intake documented in this analysis.