People are generally more likely to pass on high-calorie food when there is a tax on it - though it might not matter to everyone, a small study suggests.

In a computer-based experiment with 178 U.S. college students, researchers found that the students generally “bought” fewer lunchtime calories when sugary, high-fat fare came with a tax of 25 percent or more.

The exception was when calorie-conscious eaters were given calorie information on their lunch options; the tax did not seem to sway their decisions.

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

In the U.S., proponents of taxes on soda and junk food argue that it would not only discourage people from buying them, but could also help offset the estimated $147 billion cost of treating obesity-related ills.

Supporters also point to research suggesting that cigarette taxes have helped curb tobacco use.

Policies to require restaurants and other vendors to be frank with calorie information have made greater gains. In 2008, New York City became the first U.S. city to mandate that fast-food and coffee chains put calorie information on their menus. And in 2010, the federal healthcare reform law set national labeling requirements for certain restaurants and vending machines.

But just how effective such measures have been, or could be, is controversial.

A study reported on Tuesday, for example, found that New York City’s law has so far done little to change children and teenagers’ eating habits at fast-food restaurants.

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 - and the customer’s own calorie-consciousness.

For the study, researchers led by Dr. Janneke Giesen of Maastricht University in the Netherlands had 178 U.S. college students choose a hypothetical lunch from a computer menu on three separate occasions.

Each time, the prices for high-calorie items - like bacon cheeseburgers, brownies and chips - were increased, first by 25 percent and then 50 percent.

About half of the students were given calorie information at all lunches, while the rest were not.

Overall, Giesen’s team found, 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 were given calorie information. They ate fewer calories than their peers without any food tax, and showed little change in their eating when taxes were added.