US childhood obesity has plateaued as calorie-intake falls, studies suggest

Two-thirds of the US population is considered overweight or obese. Photograph: Fiona Hanson/PA

Two reports offer mixed signs of progress in US as 36% of adults and 17% of children remain overweight or obese

• Karen McVeigh in New York
• guardian.co.uk, 21 February 2013

Children in the US ate fewer calories in 2010 than they did a decade ago, a new health study shows. Health researchers found an overall trend towards the consumption of less carbohydrates (but more protein) than 10 years before; the percentage of calories from fat in children's diets remained broadly the same.

While the results are a promising sign that the obesity epidemic may have plateaued, children are still eating too much fat, researchers said in one of two reports published by the CDC's National Center for Health Statistics on Thursday. Two-thirds of the US population is considered overweight or obese. According to the CDC, 36% of US adults, or 78 million, and 17% of youth, or 12.5 million, are obese. Another third are overweight.

However, after years of increasing levels of obesity which have worried law and policy makers in the US and around the world, the numbers have leveled out in recent years.

R Bethune Ervin, a researcher at the Centers for Disease Control and Prevention and a co-author of both reports – Trends in Intake of Energy and Macronutrients in Children and Adolescents From 1999–2000 Through 2009–2010 and Caloric Intake From Fast Food Among Adults: United States, 2007–2010 – said that the study's findings that the energy intake and carbohydrate intake of children had decreased could be one of several factors in the stabilisation of obesity.

"With our study showing a decline at least in some groups, in energy intake and carbohydrate intake, perhaps it is a factor, although there could be lots of factors contributing to the stabilisation of obesity" Ervin said. She stressed that researchers only measured calorific intake and did not compare it to guidelines on various factors including physical activity, "so we can't say whether they are overeating or not".

Among children and adolescents aged 2–19, caloric intakes decreased for most age groups over a 10-year period. The average energy intake for boys, which was 2,258 kilocalories in 1999–2000, dropped to approximately 2,100 kilocalories in 2009–2010. Girls ate an average of 1,831 kilocalories in 1999–2000, compared to 1,755 kilocalories in 2009–2010.

The percentage of fat consumed by children was still between 11% and 12%, which is above the recommended dietary guidelines of America, which recommend less than 10% of all calories.

A similar study on calorific intake in adults over a 10-year period, carried out two years ago, showed no such drop in food intake, according to researchers. But while US adults were eating the same amount of calories, less of the calories were coming from fast food, scientists found. Frequent fast-food consumption has been shown to contribute to weight increase.

During 2007-10, adults consumed an average of 11.3% of their total daily calories from fast food, a decrease of 12.8% from 2003-1006, the study showed. No significant difference was found between men and women or between people of different income levels. However, in the youngest age group, 20-30, the percentage of calories consumed as fast food decreased significantly with increasing income levels. The decline increased with age – adults aged 60 and over consumed the lowest percentage of their daily calories from fast food.