Monday, May 11, 2009

It's all about portion control

And finally, more evidence that super sized servings are causing obesity. This just in from Reuters:
By Megan Rauscher
NEW YORK (Reuters Health) - The major reason for the obesity
epidemic that has gripped the United States in the past three decades is
increased food intake, not reduced physical activity, according to a study
released Friday at the European Congress on Obesity in Amsterdam.
The study is the first to quantify the relative contributions of food and exercise habits
to the growing number of Americans with bulging waistlines. "In the U.S., over the last 30 years, it seems that the food side of the equation has changed
much more than the physical activity side," Professor Boyd A. Swinburn, director
of the World Health Organization Collaborating Center for Obesity Prevention at
Deakin University, Melbourne, Australia, noted in a telephone interview with
Reuters Health.
Weight gain in the American population seems to be virtually all due to the consumption of more calories, with declines in physical activity playing only a minor role, Swinburn explained.
"We absolutely need to continue to promote increased physical activity and a healthy diet because they are both obviously beneficial factors in terms of obesity," he emphasized. "But
when it comes to placing priorities, I think it needs to be on reducing energy intake. It's particularly important for policymakers to focus on the energy intake side of the equation."
In the study, Swinburn and his colleagues calculated how much adults need to eat in order to maintain a stable weight and how much children need to eat in order to maintain a normal growth
curve.  They then figured out how much Americans were actually eating, using
national food supply data from the 1970s and the early 2000s. This information
allowed them to predict how much weight Americans would be expected to gain over
the 30-year study period if food intake were the only influence.
Next, the investigators determined the actual weight gained over the study period using
data from a nationally representative survey that recorded the weight of
Americans in the 1970s and early 2000s.
In children, according to Swinburn and colleagues, the predicted and actual weight increase matched exactly, which indicates that the increases in energy intake alone over the 30 years studied could explain the added pounds, they say.
In adults, the data predicted that they would be 10.8 kg (23.8 pounds) heavier, but in fact they were only 8.6 kg (18.9 pounds) heavier. This finding, Swinburn noted, "suggests that excess food intake still explains the weight gain, but that there may have been increases in
physical activity over the 30 years that have blunted what would otherwise have
been a higher weight gain."
"To return to the average weights of the 1970s, we would need to reverse the increased food intake of about 350 calories a day for children (about one can of fizzy drink and a small portion of French fries) and 500 calories a day for adults (about one large hamburger)," Swinburn noted
in a statement from the meeting.
"Alternatively, we could achieve similar results by increasing physical activity by about 150 minutes a day of extra walking for children and 110 minutes for adults, but realistically, although a combination of both is needed, the focus would have to be on reducing calorie
intake," he added
How much more evidence do we need before we apply pressure to restaurants (especially fast food) to reduce portions?