The Times has run into similar trouble with other prominent articles purporting to cut through the supposed mystery of why the world keeps getting dangerously fatter. One such piece pointed the finger at sugar and high-fructose corn syrup, another at bacteria. But perhaps the most controversial of the Times’s solution-to-the-obesity-crisis articles was the magazine’s cover story in 2002, by science writer Gary Taubes, that made the case that high-fat diets are perfectly slimming—as long as one cuts out all carbohydrates. His article’s implicit claim that copious quantities of bacon are good for weight loss, while oatmeal, whole wheat, and fruit will inevitably fatten you up, had an enormous impact on the public’s efforts to lose weight, and to this day many people still turn to Atkins and other ultra-low-carb, eat-all-the-fat-you-want diets to try to shed excess pounds. Unfortunately, it’s an approach that leaves the vast majority of frontline obesity experts gritting their teeth, because while the strategy sometimes appears to hold up in studies, in the real world such dieters are rarely able to keep the weight off—to say nothing of the potential health risks of eating too much fat. And of course, the argument Taubes laid out stands in direct opposition to the claims of the Parker-Pope article. Indeed, most major Times articles on obesity contradict one another, and they all gainsay the longstanding consensus of the field.

The problem isn’t unique to the Times, or to the subject of weight loss. In all areas of personal health, we see prominent media reports that directly oppose well-established knowledge in the field, or that make it sound as if scientifically unresolved questions have been resolved. The media, for instance, have variously supported and shot down the notion that vitamin D supplements can protect against cancer, and that taking daily and low doses of aspirin extends life by protecting against heart attacks. Some reports have argued that frequent consumption of even modest amounts of alcohol leads to serious health risks, while others have reported that daily moderate alcohol consumption can be a healthy substitute for exercise. Articles sang the praises of new drugs like Avastin and Avandia before other articles deemed them dangerous, ineffective, or both.

What’s going on? The problem is not, as many would reflexively assume, the sloppiness of poorly trained science writers looking for sensational headlines, and ignoring scientific evidence in the process. Many of these articles were written by celebrated health-science journalists and published in respected magazines and newspapers; their arguments were backed up with what appears to be solid, balanced reporting and the careful citing of published scientific findings.

But personal-health journalists have fallen into a trap. Even while following what are considered the guidelines of good science reporting, they still manage to write articles that grossly mislead the public, often in ways that can lead to poor health decisions with catastrophic consequences. Blame a combination of the special nature of health advice, serious challenges in medical research, and the failure of science journalism to scrutinize the research it covers.

Personal-health coverage began to move to the fore in the late 1980s, in line with the media’s growing emphasis on “news you can use.” That increased attention to personal health ate into coverage of not only other science, but also of broader healthcare issues. A 2009 survey of members of the Association of Health Care Journalists found that more than half say “there is too much coverage of consumer or lifestyle health,” and more than two-thirds say there isn’t enough coverage of health policy, healthcare quality, and health disparities.

The author of a report based on that survey, Gary Schwitzer, a former University of Minnesota journalism researcher and now publisher of healthcare-journalism watchdog, also conducted a study in 2008 of 500 health-related stories published over a 22-month period in large newspapers. The results suggested that not only has personal-health coverage become invasively and inappropriately ubiquitous, it is of generally questionable quality, with about two-thirds of the articles found to have major flaws. The errors included exaggerating the prevalence and ravages of a disorder, ignoring potential side effects and other downsides to treatments, and failing to discuss alternative treatment options. In the survey, 44 percent of the 256 staff journalists who responded said that their organizations at times base stories almost entirely on press releases. Studies by other researchers have come to similar conclusions.

David H. Freedman is a contributing editor at The Atlantic, and a consulting editor at Johns Hopkins Medicine International and at the McGill University Desautels Faculty of Management.