Since processed foods account for most of the salt in the American diet, national health officials, Mayor Michael R. Bloomberg of New York and Michelle Obama are urging food companies to greatly reduce their use of salt. Last month, the Institute of Medicine went further, urging the government to force companies to do so.

But the industry is working overtly and behind the scenes to fend off these attacks, using a shifting set of tactics that have defeated similar efforts for 30 years, records and interviews show. Industry insiders call the strategy “delay and divert” and say companies have a powerful incentive to fight back: they crave salt as a low-cost way to create tastes and textures. Doing without it risks losing customers, and replacing it with more expensive ingredients risks losing profits.

When health advocates first petitioned the federal government to regulate salt in 1978, food companies sponsored research aimed at casting doubt on the link between salt and hypertension. Two decades later, when federal officials tried to cut the salt in products labeled “healthy,” companies argued that foods already low in sugar and fat would not sell with less salt.

Now, the industry is blaming consumers for resisting efforts to reduce salt in all foods, pointing to, as Kellogg put it in a letter to a federal nutrition advisory committee, “the virtually intractable nature of the appetite for salt.”

The federal committee is finishing up recommendations on nutrient issues including salt. While its work is overseen by the Department of Agriculture, records released to The New York Times show that the industry nominated a majority of its members and has presented the panel with its own research. It includes two studies commissioned by ConAgra suggesting that the country could save billions of dollars more in health care and lost productivity costs by simply nudging Americans to eat a little less food, rather than less salty food.