There’s a deep sense of irony in adding to a never-ending series of headlines on a study that shouldn’t have had any attention paid to it at all. But the publication on the dangers of the “paleo” diet that’s spawned countless headlines is so flawed that it’s worth exploring why it got so much attention.

“Diabetes expert warns paleo diet is dangerous and increases weight gain,” claims the press release issued to promote a paper in last week’s Nature Nutrition and Diabetes. What's particularly flabbergasting about this situation is that the study didn’t actually have anything to do with a paleo diet—it used a low-carb, high-fat (LCHF) diet. The two diets can be similar—paleo diets tend to be lower in carbs and higher in fats—but they’re not the same thing, and it’s possible to eat a paleo diet that’s not high in fat.

The headline also doesn’t mention that the study looked at mice. But not many mice—only seventeen male New Zealand Obese (NZO) mice, which are inbred to be severely predisposed to obesity and diabetes. Given that the study wanted to find out whether the diet is suitable for obese, pre-diabetic people, it makes sense to study mice with a predisposition toward these conditions. But it does mean that the results don't apply more broadly. “It’s not even applicable to all mice, let alone all humans,” says Yoni Freedhoff, an assistant professor at the University of Ottawa with a specialty in debunking diet nonsense.

The motivation for examining a LCHF diet is sensible: some people think a LCHF diet could be good for diabetes because eating meals that are very low in carbs should help keep blood glucose levels low, reducing the need for insulin secretion and ultimately staving off insulin resistance and diabetes. But although low carbohydrates could be a good idea, the high fat content might be a cause for concern. We don’t yet fully understand what a diet like this will do to liver and pancreatic function, let alone weight control.

Unfortunately, the methods used to explore this question are eyebrow-raising. First, the researchers fed all seventeen mice a standard diet for six weeks. This diet consisted of 20 percent protein, 70 percent carbs, and 10 percent fat; it had 3,224 digestible kilocalories per kilogram of food.

Then, at six weeks old, nine of the mice were switched to a LCHF diet for 9 weeks. Their diet now consisted of 13 percent protein, 6 percent carbs, and a staggering 81 percent fat. “That’s not what generally gets recommended to people on LCHF diets, in my experience,” says Freedhoff. “That would be a very challenging diet for a human being to undertake.” This food had 5,732 digestible kilocalories per kilogram—about 1.8 times the amount in the original diet.

The LCHF mice got fatter. Weirdly, the paper says they didn’t actually eat more calories than the standard-diet mice; in fact, it suggests they ate fewer calories, but it doesn’t give any explanation for how or why this might have happened. The fact that they gained so much weight while eating fewer calories “doesn’t make a lot of physiological sense,” says Freedhoff. Coupled with the very small number of mice, it’s especially troubling, he adds; if they had found this result across thousands of mice, “it would perhaps be more robust.”

So why did this study get so much attention? People love talking about diets, and they especially love arguing about diets. But research on diets is so fraught with difficulty, says Freedhoff, that “any diet that believes it has incontrovertible proof of superiority over any other for long-term health or weight management is kidding itself.” In a nutshell, people just don’t follow the diets they’re prescribed, which means that nutrition studies are either based on the very faulty system of patient recall or constrain participants in an artificial controlled environment for the duration of the study. Consensus in the field is limited, and it gravitates toward a few pretty obvious claims.

Despite there being some decent reasons to be skeptical of both the paleo diet and the LCHF diet, this study and ensuing press release are not among the better reasons for skepticism. Ultimately, both diets can be helpful because people have individual preferences and tolerances for what they find sustainable, and any diet that gets people eating more vegetables and less junk food can be helpful, Freedhoff argues.

"You need to be very careful with fad diets,” said the paper’s lead author, Sof Andrikopolou, in the press release (he's a proponent of the Mediterranean diet). “Always aim for diets backed by evidence.” Better evidence than this, hopefully.

Nature Nutrition and Diabetes, 2015. DOI: 10.1038/nutd.2016.2 (About DOIs).