Over the past quarter-century, historical research has revealed how major industries from tobacco to lead to petroleum have meddled in science to conceal the hazards of their products. Drawing on secret industry documents, these studies have shown how special interests have used financial incentives to influence scientists, fabricate doubt, and delay regulation. Recently, similar allegations have been made against the sugar industry, with claims that prominent industry-backed researchers in the 1960s downplayed or suppressed evidence linking sugar and heart disease. Building on a newly popular narrative holding that the low-fat campaign of the 1980s was not based on solid science, these allegations have suggested that if not for the machinations of the sugar industry and its cadre of sponsored researchers, the history of U.S. dietary policy might have unfolded very differently. In this article, we argue that the historical evidence does not support these claims. Although we do not defend the sugar industry and cannot address every aspect of this history, we believe recent high-profile claims come from researchers who have overextended the analogy of the tobacco industry playbook and failed to assess historical actors by the norms and standards of their time. Our analysis illustrates how conspiratorial narratives in science can distort the past in the service of contemporary causes and obscure genuine uncertainty that surrounds aspects of research, impairing efforts to formulate good evidence-informed policies. In the absence of very strong evidence, there is a serious danger in interpreting the inevitable twists and turns of research and policy as the product of malevolent playbooks and historical derailments. Like scientists, historians must focus on the evidence and follow the data where they lead.