Food tax could trim some peoples' calorie intake

Would you still reach for those french fries if their price was jacked up by a substantial tax? A study says not everybody would.

Junk food taxes and greater openness with calorie information have both been advocated as ways to help consumers limit their calorie intake -- and, the hope is, to keep their weight in a healthy range.

In a computer-based experiment with nearly 200 US college students, researchers led by Janneke Giesen of Maastricht University in the Netherlands found that the students generally "bought" fewer lunchtime calories when sugary, high-fat fare came with a tax of 25% or more.

"The most important finding of our study is that a tax of 25% or more on (high-calorie) foods makes nearly everyone buy fewer calories," Giesen told Reuters Health in an email.

The exception was when calorie-conscious eaters were given calorie information on their lunch options, in which case the tax did not seem to sway their opinions.

Policies to require restaurants and other vendors to be frank with calorie information have made gains recently -- most notably in New York, which in 2008 became the first US city to mandate that fast food restaurants and coffee chains put calorie information on their menus. But just how effective such measures have been, or could be, is controversial.

The current study, reported in the American Journal of Clinical Nutrition, suggests that the effectiveness of junk food taxes might partly depend on whether calorie information is given or not, as well as the customer's own awareness of calories.

Giesen and colleagues had 178 US college students choose a hypothetical lunch from a computer menu on three separate occasions. Each time, the prices for high-calorie items such as bacon cheeseburgers, brownies and chips, were increased -- first by 25%, then 50%..

Overall, students tended to order fewer calories when a junk food tax was in place. They curbed their average calorie intake by about 100 to 300 calories, depending on the tax in place.

The only students who did not respond to the price increases were those who were already watching their diets and given calorie information. They ate fewer calories than their peers without any food tax, and showed little change in their eating when the tax was added.

"However, if one wants to help people in general to prevent caloric overconsumption, then our results indicate that imposing a high tax on (high-caloric) food items is much more efficacious," Giesen said.

Barry Popkin, a professor of nutrition at the University of North Carolina, Chapel Hill, said that while the study had limitations, including the small sample size, its results fit with larger experiments that suggest a junk food tax might work.

But Industry trade groups argue that there is no evidence the taxes will fight obesity and say that these taxes would unfairly burden low-income families.