U.S. Food and Drug Administration Commissioner Robert Califf defended the agency's role in addressing the country's obesity epidemic as he was grilled by senators over FDA regulation of the food and beverage industry on Thursday.

The hearing of the Senate Committee on Health, Education, Labor and Pensions follows President-elect Donald Trump's selection of Robert F. Kennedy Jr, to lead the Department of Health and Human Services, the country's top health agency. Kennedy, a vaccine skeptic, has also said those at the agency in charge of nutrition labels on food have "to go."

Kennedy has criticized popular weight-loss drugs such as Novo Nordisk's Wegovy and called for removing ultra-processed foods from school lunches as part of a goal to reduce the incidence of diet-related chronic diseases.

"We have just completed the largest reorganization in FDA's history, in no small part, so that we could take on the issues of nutrition and chemicals in our food supply," Califf said during testimony to the Senate committee led by Bernie Sanders.

Sanders and other senators questioned agency officials over several regulations related to the food and beverage industry, including a delayed proposal to require nutrition labels on the front of products.

"According to the CDC, the rate of childhood obesity in America has tripled since the 1970s, and from where I'm standing here the FDA has not responded in any way with the urgency of the crisis. How long does it take to put a bloody label on a product?" Sanders said.

Califf said the agency was trying to do its part within its authority and budget.

"As you know, I'll be leaving FDA (with) the change of administrations, but I can assure you that our people at FDA want to do more, and we need your partnership," he said.

Califf, a cardiologist and researcher, has held the role of FDA commissioner for a second time since 2022. He previously led the world's most influential health regulator during the Obama administration between 2016 and 2017.

Trump has nominated surgeon and author Martin Makary to succeed Califf as FDA Commissioner.

Califf said the research around popular new weight-loss drugs had helped understanding of the addictive nature of some of the foods that Americans consumed. Unlike with drugs, he emphasized that the agency did not have insight into research done by the food industry.

Lawmakers grilled Califf, and FDA executive James Jones, who has been tasked with leading the agency's new human foods program, over the use of food dyes and criticized inadequate and complex labeling of plant-based and genetically-engineered products.

Califf said the FDA had repeatedly asked for better funding for chemical safety, calling it a huge priority. He added that the agency was also trying to recruit more employees for food manufacturing site inspections, but said it did not always have the resources to do so.

(Reporting by Bhanvi Satija and Christy Santhosh in Bengaluru and Leah Douglas in Washington; Editing by Bill Berkrot)