WASHINGTON - Congressional Republicans are pushing back against proposed dietary guidelines that urge Americans to consider the environment when deciding what foods to eat.

House and Senate spending bills say the guidelines must focus only on nutrition and diet. That's a clear effort to thwart a recommendation by the Dietary Guidelines Advisory Committee that eating a diet higher in vegetables and other plant-based foods is better for the environment than eating a diet based more on foods from animals.

The advice from a government advisory panel of independent doctors and nutrition experts has raised the ire of the meat industry.

The dietary guidelines come out every five years, and the government advice informs everything from school lunches and food package labels to advice from your doctor. The departments of Agriculture and Health and Human Services are expected to issue a final version by year's end based on the advisory committee's February recommendations.

While the guidelines always have been subject to intense lobbying by food industries, this year's version has set off unprecedented political debate, fueled by Republicans' claims the Obama administration has gone too far in telling people what to eat.

The advisory panel also suggested a tax on sugary drinks and snacks as one way people could be coaxed into eating better. That idea angered beverage companies and conservatives in Congress.

Two spending bills in the House would set a new threshold for the science that can be used in setting the guidelines, saying the government only can make recommendations based on the strongest science. One of the bills was approved by a spending subcommittee last week, while the other was approved by the House Appropriations Committee Wednesday. Rep. Rosa DeLauro, D-Conn., offered an amendment to strike the dietary guidelines language from the bill but it was rejected.

The guidelines panel had used three grades to determine the strength of the science supporting its recommendations: Grade 1 is strong, Grade 2 is moderate and Grade 3 is limited.

The advisory committee sent a letter to lawmakers Tuesday strongly opposing the legislation.

"I don't think public policy should be driven by the economic interests or the lobbyists," panel chairman Barbara Millen said in an interview. "It needs to be driven by science, and good science."

Millen said "strong" recommendations are unlikely to change over the years and are much harder to come by with limited research dollars.

The recommendation that a more plant-based diet is better for the environment is based on science rated "moderate" in the report. The moderate threshold means there's a strong body of scientific evidence to support the recommendation, but it's not as conclusive.

"Research evolves and we expect it to change," Millen said. "That doesn't negate the importance of a large body of consistent data that may have limitations of a certain kind."

Rep. Robert Aderholt, the author of one of the House bills, said the goal "should not be to 'dumb down' the standards but instead increase the science certainty of each guideline." Aderholt, R-Ala., also has pushed back against healthier school lunch rules, and his bill tries to delay federal menu labeling requirements.

Republican Rep. Tom Cole of Oklahoma, the author of the other House spending bill, said the advisory committee had "enormously expanded" the scope of the guidelines.

The bill has frustrated groups such as the American Cancer Society, which says the legislation could strip the dietary guidelines of a recommendation that reducing consumption of red meat and processed meats can lower the risk of colon cancer. The cancer society's own guidelines have long urged people to take the same step.