Many people have since commented on how the press coverage was based on unpublished, non–peer-reviewed results. It is fair to criticize media outlets for highlighting such preliminary research but also the AHA for promoting it. There is nothing wrong with poster presentations and preliminary research, but there should have been more circumspection before presenting it for public consumption.
Diet Quality and Multiple Analyses
Beyond these surface-level objections were some more substantive issues. The study was, by nature, observational and therefore prone to confounding. Researchers adjusted for relevant variables, but as we have learned multiple times in the past, residual confounding is always a potential issue. Also, researchers didn't have information on the quality of the study participants' diet. If someone breaks their 16-hour fast with ultraprocessed junk food, the type of food might be more relevant to long-term cardiovascular health than when it was eaten. People may have engaged in intermittent fasting because they had shift work or an irregular sleep schedule, which are independent cardiovascular risk factors. It's also possible that people adopted time-restricted eating as a dietary strategy precisely because they were at high risk for cardiovascular disease, an association that could be explained by reverse causation. Suffice it to say, many other external factors might be at play here.
