Study: Junk food not related to obesity
Total diet, environment determines how we handle weight
Consumption of "junk food" is unrelated to weight for the vast majority of Americans, according to a new study suggesting that weight loss efforts focusing on these foods are too simplistic.
For 95 percent of Americans, the study found no significant relationship between one's body mass index, or BMI, and junk food consumption. The exceptions were the underweight and the most morbidly obese.
The study defined junk foods as soft drinks, French fries, desserts and sweet and salty snacks. These foods are widely regarded as a major cause of the obesity pandemic that has inflated the American waistline -- and rates of diseases such as type 2 diabetes -- for decades.
Junk foods have been condemned by the medical community, banned from school lunch programs, and targeted by politicians. Former New York City Mayor Michael Bloomberg pushed a ban on big sodas that wasstruck down last year.
But losing the pounds and keeping them off is more complicated than turning down the chili-cheese fries, the study indicates.
The message is that weight-watchers and public policy makers need to consider the whole nutrition picture instead of fixating on a few factors, said David R. Just, who led the study with Brian Wansink.
“It’s not just these foods, and we can’t just target these foods,” Just said. “It’s really the entire diet ... If we’re talking about food policy to curb obesity, if all we do is pick out a few villain foods, our policy is going to be pretty ineffective.”
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The study was published Thursday in the journal Obesity Science & Practice. Go toj.mp/studyjunkfood for the study. No outside funds were used in the study, the authors say.
According to a previous study by Just, banning junk foods can actually backfire, as they become more desirable. Children who can’t get cookies at school might eat more at home, for example. A better strategy would be to make junk foods harder to get to, he said, perhaps by placing them in an inconvenient location.
It remains to be seen whether this new finding will hold up under additional research. So it’s not a green light to cram down mass quantities of chili-cheese fries. However, it does provide yet another example of how nutritional beliefs once regarded as unassailable fact, such as the role of fats and salt in cardiovascular disease, has been undermined by further study.
Responses
Researchers used weight and diet information from 5,000 people interviewed in 2007-2008 by the Centers for Disease Control and Prevention's National Household and Nutrition Examination Survey. They were adults of 18 years or older, who completed two detailed surveys of what they ate in a 24-hour period.
A slight negative correlation was actually found between body mass index and consuming junk food, Just said. In other words, those with a lower BMI consumed a bit more. However, the correlation was not significant.
Two physicians not involved in the study gave differing reactions.
Dr. Ken Fujioka, an endocrinologist and weight loss specialist at Scripps Health, said he was skeptical of the study because it was based on observational and epidemiological research. A controlled, randomized trial would produce more rigorous results.
Fujioka has long maintained that observational studies are insufficient because they merely establish correlation, while randomized controlled studies can establish cause and effect.
A more positive reading of the study was provided by Dr. Eduardo Grunvald, program director of the UC San Diego Weight Management Program.
“It does not surprise me at all,” Grunvald said. “When you’re talking about obesity, you’re really talking about weight regulation. You can never target just one aspect and make a huge impact. When I treat patients, I have to look at every single aspect from their diet to their physical activity, to their medication, to their social support, to their microenvironment to their macroenvironment.”
“I can’t tell someone if you stop drinking sodas or stop eating candy bars you’re all of a sudden going to lose 30 pounds and keep it off,” Grunvald said.
Compensatory eating can defeat junk food avoidance, Grunvald said.
In general, adopting specific diets to lose weight doesn’t produce long-lasting results, he said.
“What you really have to do is change someone’s environment so that making decisions is much easier,” he said. “Just relying on sheer willpower really doesn’t work.”
A changed environment can mean providing social support, so that sustaining a desirable eating pattern doesn’t require constant effort.
“The more you have to think about each step, the harder it is,” Grunvald said.
Calories rising
“It’s probably what arises when people who are overweight become conscious of their weight and try to cut back on things they think make them fat,” Just said. He also cautioned about interpreting the study to mean that increasing junk food consumption won’t increase weight.
“There are a bunch of good studies that show if you drink too much soda, you gain weight, or too much cake, or whatever the junk food is,” he said. The study makes a more subtle point: that reducing junk food consumption in isolation isn’t likely to help.
A more likely explanation for the increase in obesity is an increase in overall calories consumed in recent decades.
“It’s not like we had a great wave sweep into the U.S. where everybody suddenly woke up to the great taste of cola,” he said.
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