Robert H. Lustig is an American pediatric endocrinologist at the University of California, San Francisco where he is a Professor of Clinical Pediatrics. He practices in the field of neuroendocrinology, with an emphasis on the regulation of energy balance by the central nervous system. He also has a special interest in childhood obesity.
Lustig came to public attention through his efforts to establish that fructose can have serious deleterious effects on human health if consumed in too large amounts. On May 26, 2009, he delivered a lecture called "Sugar: The Bitter Truth" which was posted on YouTube the following July and "went viral" with some 4.2 million viewings. In his lecture, Lustig calls fructose a "poison" and equates its metabolic effects with those of ethanol.