The new data from the Centers for Disease Control and Prevention (CDC) published in the American Journal of Clinical Nutrition summarises the findings of the nine National Health and Nutrition Examination Surveys (NHANES) the CDC has conducted between 1971 and 2010. Several thousand adults aged 20-74 were randomly selected every two to four years and asked to recall what they ate over the previous 24 hours.
What they found was that among adults, average daily energy intake rose by a total of 314 calories from 1971 to 2003, then fell by 74 calories between 2003 and 2010.
In a recent interview with the Reuters news agency, William Dietz, former CDC director of Nutrition, Physical Activity and Obesity and co-author of the study said: “It’s hard to reconcile what these data show, and what is happening with the prevalence of obesity. Seventy-four calories is a lot … and we would expect to see a measurable impact on obesity”.
Indeed a deficit of 74 calories a day, all things being equal, should produce nearly 8 pounds (3.5 kilos of weight loss) over the course of a single year.
And yet in that same time-frame the percentage of women who are obese in the US remained steady at 35% and the percent of men who are obese rose from 27 to 35%.
According to Dietz obesity rates should have levelled-off for both sexes and to be decreasing at this point, if people are consuming fewer calories.
The CDC released similar results last month for children: boys have cut their daily calorie intake by 150, and girls by 80, since 1999. Nevertheless the pattern in weight is similar to that of adults with obesity rates for girls holding steady and rising amongst boys.
For a more helpful explanation for what’s going wrong, it’s worth looking at the work of endocrinologist Robert Lustig, author of the book Fat Chance: Beating the Odds Against Sugar, Processed Food, Obesity, and Disease, which deconstructs the mythology of fat. According to Lustig exercise, for all its benefits, won’t help you shed pounds and fasting only worsens weight gain.
