Robert Lustig on Ultra-Processed Food: warns against

Dr. Robert Lustig warns against ultra-processed food (NOVA class 4), saying modern UPF products are not healthy and that current U.S. ultra-processed products fail his metabolic-matrix test. In a March 2026 interview, he carved out a nuance: re-engineered UPF could theoretically pass his three-precept test (protect the liver, feed the gut, support the brain), though he says today’s products do not.

His stated reasoning is that processing strips fiber, adds sugars and additives, and breaks the three metabolic precepts — which is also the basis of his harm-reduction reformulation work with KDD, aimed at making processed products metabolically healthier rather than asking consumers to avoid all processed food.

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