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Eat spaghetti, lose weight? Message from Big Pasta-funded study needed more scrutiny from journalists

Kathlyn Stone is an associate editor with HealthNewsReview.org. She tweets as @katkstone.

Like father like sonA news release from Italy’s Neuromed Institute this week is driving media outlets from the U.S. to China (and all points in between) to react excitedly to the “best study ever” on pasta.

The release claims that pasta contributes to a lower body-mass index, lower waist circumference, and “better waist-hip ratio.” It doesn’t include any data – no quantification of results, no description of the evidence such as how the data was collected and measured, and it doesn’t say who funded the study, which we’ll get to in a bit. The release does have plenty of platitudes:

  • “pasta consumption is actually associated with a reduced likelihood of of both general and abdominal obesity”
  • “By analyzing anthropometric data of the participants and their eating habits – explains George Pounis, first author of the paper – we have seen that consumption of pasta, contrary to what many think, is not associated with an increase in body weight, rather the opposite. Our data show that enjoying pasta according to individuals’ needs contributes to a healthy body mass index, lower waist circumference and better waist-hip ratio”.

The brief release concludes with a fairly honest assessment. “The message emerging from this study…is that Mediterranean diet, consumed in moderation and respecting the variety of all its elements (pasta in the first place), is good to your health.”

There’s plenty of evidence that the Mediterranean Diet is a good balanced diet comprised of fresh fish and vegetables, olive oil, whole grains, legumes and nuts. And there’s little doubt that pasta can play a role as part of that diet pattern. But do these facts support the idea that pasta “isn’t fattening” and “contributes to a health body mass index”? The release appears to twist itself into a fusilli to make this point, and does so without broader context on the study’s significant limitations or its practical real-world implications.

Tell the people what they want to hear

Predictably, many of the headlines sparked by the superficial news release also conveyed misleading messages about the findings.

Turns Out Pasta Isn’t Fattening — and Can Actually Help You Lose Weight

Pasta doesn’t make you fat, say Italian scientists

Pasta may promote weight loss

Upending years of misconceptions, researchers have found that eating pasta can keep us lean

Eating pasta makes you slimmer, apparently

This Study on How Pasta Can Help You Lose Weight Is Easily the Best Science of 2016

But is there another side to this story?

We asked nutrition research expert Christopher Gardner, PhD, professor of medicine at the Stanford Prevention Research Center, to weigh in on the pasta hoopla brought about by the Italian study. He suggests that the associations drawn between pasta consumption and weight in the study aren’t nearly as solid as these headlines would have us believe.

“The various headlines seem to indicate ‘Despite the impression that eating more pasta leads to weight gain, in fact it leads to weight loss….you should eat pasta,’” says Gardner. “It is possible that statement is true, but the study that was published does very little to support this. The published study provides a somewhat torturous piece of evidence that it could be possible.” [Emphasis Gardner’s]

The study, published in Nature’s Nutrition & Diabetes journal, should have been served up with a side of caveats and qualifiers that mostly didn’t make it into the coverage. For example:

  • The study, which is actually based on cross-sectional data taken from two separate data sets, is observational in nature and does not prove cause-and-effect. So the release’s contention that pasta “contributes to a lower body mass index” isn’t supported by the results. In fact, we don’t know what effect, if any, eating pasta may have had on participants’ weight in this study.
  • One of the groups studied (the INHES group of 14,402) completed a single survey of what they’d consumed in just one 24-hour period. The published study states: “The one 24-h dietary recall could not be considered as representative of the dietary habits of an individual. The telephone-based interviews are under the limitation of mis-reporting and or under/over-estimation of food consumption. The body weight and height was self reported and under the related bias.”
  • In the other group of 8,964 people studied (the Moli-Sani group), dietary information was retrieved only once and “may be prone to recall bias and seasonal variation.”

There are quite a few other holes, as well.

“The fatal flaw in all of this is trying to pull one nutrient or one food out of the mix and attributing benefit or harm, when in fact people don’t eat individual nutrients or individual foods,” says Gardner. “In this case, there were people following a Mediterranean diet, more closely, or less closely, and pasta was one of dozens of components of that diet pattern.”

Data adjustments make findings ‘more contrived and less straightforward’

Gardner noted that one of the tables in the study showing the crude data analysis indicates that obese men and women reported eating more pasta than under-, normal-, or overweight individuals. The data collection methods were inaccurate, however, and the authors use adjustments to mathematically correct those errors. Gardner says:

These are legitimate adjustments, but nonetheless they make the associations drawn just that  much more contrived and less straightforward. Translated to English….you can’t tell what the relationship is because the data collected are very inaccurate, so if we manipulate them with reasonable assumptions to hopefully make them more accurate the relationship actually flips from pasta being associated with higher BMI, to pasta being associated with lower BMI.

Of course, not every reporter was satisfied to base their entire story on the sunny news release. Some actually looked at the study, sought an outside perspective, and brought some critical analysis to bear on the subject.

After a breathless headline and lead, Susan Rinkunas at New York Magazine did point out some problems with the “best study ever,” such as: “If this all sounds too good to be true, remember that observational studies can’t prove cause and effect; there are likely lots of other factors at play here.”

NJ.com’s Kathleen O’Brien was also on to something when she wrote: “But might there be some caveats within the study’s fine print?”

From reading the study she learned that those who consumed pasta were likely to follow a Mediterranean diet, “so to the extent that it enticed them in that direction, it helped them avoid obesity, the researchers concluded.” In other words, increased pasta consumption may have been a marker for a more healthful overall diet in the groups studied.

She also spotted what may be “bad news for Americans.” What’s considered a “large” portion of pasta in Italy (86 grams or 3 ounces) is considered “measly” in the US, O’Brien noted. So forget about that “Never Ending Pasta Bowl” featured at some American chain restaurants, she says.

Business Insider noticed that Barilla, the world’s largest pasta maker and whose labels are familiar on US store shelves, was a funder of the study, along with the Italian Ministry of Economic Development. That certainly wasn’t highlighted in any of the other stories listed above.

The takeaway for journalists and consumers

When something looks too good to be true, it probably is. The same with a promise – even from scientists – that you can indulge in your favorite foods in order to lose weight.

All of this can be summed up in a quote attributed to Italian-American chef and Food Network television host Giada De Laurentiis. Speaking to People magazine in 2013 she said,

Pasta doesn’t make you fat. How much pasta you eat makes you fat.”

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Comments (1)

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George Henderson (@puddleg)

July 11, 2016 at 5:28 am

This is a good summary, especially Chris Gardner’s comments. I want to add one thing – the results, such as they are, are presented as Pearson’s coefficients, that is, (if I understand correctly) they give the calculated degree of concordance between pasta and weight. This results in a number that no-one can apply to their own life, because it does not tell us – how much pasta? How much weight difference? What are the odds, based on the study, of an individual who eats x amount of pasta gaining or losing weight? These sorts of figures could have been generated from the data (I’m not saying they would have been accurate at all, but they would have been possible for a reasonably intelligent person to understand) but a different decision was taken, and the likely reason for this is that any real difference was trivial.