NEW YORK (Reuters) - Kind LLC wants a U.S. federal agency to change its standards for what can be labeled as healthy, months after the snack bar maker received a warning letter for using the term on packaging for bars that were deemed too fatty.

Kind argues that fat from items like fruits, vegetables, nuts and whole grains should not be counted in the tally, in a citizen petition the company said it plans to file with the U.S. Food and Drug Administration on Tuesday, a copy of which was seen by Reuters.

An FDA spokeswoman declined comment, but said the agency would respond directly to Kind once a petition is filed. Kind's petition would be reviewed by the agency's commissioner and open for public comment, according to the FDA's process for dealing with petitions.

The dispute represents a new front in an emerging battle over what is officially considered healthy in the United States, in the light of dietary research over the past two decades pointing to processed sugar in foods, rather than fat, as a greater threat to health.

Under current rules laid down by the FDA, foods labeled as healthy must contain less than 3 grams of total fat and less than 1 gram of saturated fat per serving.

Kind, known for its nut-based bars wrapped in clear packaging, received a warning letter in March from the FDA for exceeding those limits.

“Once we learned that we had not done a couple of regulatory things correctly and we fixed them, we delved deeper into understanding the rationale of those regulations,” said Daniel Lubetzky, Kind’s founder and chief executive, in an interview. “There was one aspect to those regulations that we really felt was not in the interest of public policy.”

Created in 1993, when dietary recommendations focused on limiting fat intake rather than sugar, the rules prohibit foods that are nutrient-dense from being marketed as healthy, Lubetzky said. Products such as sugary cereal and low-fat pudding meet the definition while foods like avocados and salmon are too high in fat.

Some experts said that while they do not endorse Kind bars specifically, the FDA should update food labeling standards to reflect changing views on fat.

The case of Kind "shows the fragmented and outdated nature of a lot of our federal policy," said Dariush Mozaffarian, Dean of the Friedman School of Nutrition Science & Policy at Tufts University.

(Reporting by Anjali Athavaley; Editing by Bill Rigby)