Health Secretary Robert F. Kennedy Jr. escalated his war against the food industry on Tuesday, declaring that “sugar is poison.”

Mr. Kennedy’s comment came during a highly publicized news conference where he also asserted that he has “an understanding” with major food manufacturers to remove petroleum-based food colorings from their products by 2026.

No one from the food industry attended the event, and none have publicly agreed to Mr. Kennedy’s demands, although the International Dairy Foods Association has pledged to eliminate artificial colors in milk, cheese and yogurt sold to schools as part of the federal lunch and breakfast programs by the start of the 2026 school year.

However, Mr. Kennedy and his advisers said that every major food manufacturer and some fast-food companies have contacted the agency looking for guidance.

“Four years from now, we are going to have most of these products off the market, or you will know about them when you go to the grocery store,” Mr. Kennedy said.

Mr. Kennedy’s push to get food manufacturers to remove dyes from their products is his first effort at sweeping reform of the food industry, which he has long blamed for creating and marketing ultra-processed foods that he says are making Americans obese and contributing to a host of diseases, including diabetes and heart disease.

He ratcheted up his campaign with the remark about sugar, lamenting that government agencies recommend “a huge amount of sugar” for children, “and it’s hurting them, and it’s addicting them, and it’s changing their taste buds.”

The Food and Drug Administration recommends that added sugar — sugar that is not found naturally in foods, including fruit — account for no more than 10 percent of the diet for both children and adults.

“Sugar is poison,” Mr. Kennedy said, “and Americans need to know that it’s poison.”

Critics of Mr. Kennedy say that while his goal of making the food supply healthier is laudable, the cuts he is making to scientific research grants, coupled with significant staff reductions at agencies like the F.D.A. and the National Institutes for Health, will hinder his efforts. The very same people who police the food industry, they pointed out, are now out of jobs.

Some have quit in frustration. The leading nutrition scientist at the N.I.H., Kevin Hall, recently resigned, saying he was being censored. Jim Jones, the chief of the F.D.A.’s food division, quit last month, saying “indiscriminate” layoffs would make it “fruitless” for him to continue.

“I was looking forward to working to pursue the department’s agenda of improving the health of Americans by reducing diet-related chronic disease and risks from chemicals in food,” Mr. Jones wrote at the time.

Mr. Kennedy delivered his remarks in the grand hall of the Department of Health and Human Services on a stage filled with so-called MAHA Moms — women who power his “Make America Healthy Again” movement — and their children.

He was joined by Dr. Marty Makary, the F.D.A. commissioner; Dr. Jay Bhattacharya, the director of the National Institutes of Health, and Republican leaders of states that have signed onto his MAHA movement, including the governor of West Virginia, who recently signed legislation banning dyes in most foods.

Dr. Makary said he expected cooperation from the food manufacturers.

“You win more bees with honey than fire,” Dr. Makary said, adding “I believe in love, and let’s start in a friendly way and see if we can do this without any statutory or regulatory changes.”