Have you seen the latest headlines about pasta?
You know, the ones that excitedly declare that it can help you lose weight.
Here are some examples:
Eating Pasta Linked to Weight Loss in New Study
Eating Pasta Can Help You Lose Weight, New Study Reports
Pasta Was Linked to Weight Loss in a New Study–and We Know What We’re Having for Dinner Tonight
Eating Pasta May Help With Weight Loss, Study Finds
Study Finds Pasta Can Help You Lose Weight
Eating Pasta 3 Times a Week Won’t Make You Gain Weight, According to a New Study — and It Could Even Help You Lose It
There’s a glaring problem with these headlines – and you don’t even have to read the study to figure it out.
Claiming that any particular food “can help you lose weight” or is “linked to weight loss” is incredibly dishonest.
It also oversimplifies weight loss, which is, in reality, a complex subject.
Saying that pasta is linked to or causes weight gain is just as dishonest, by the way.
The truth is far more complicated.
But the cringe-worthy headlines aren’t even the worst thing about this debacle.
The “research” itself is bizarre.
Let’s take a look at the study that inspired the headlines above.
Titled Effect of pasta in the context of low-glycaemic index dietary patterns on body weight and markers of adiposity: a systematic review and meta-analysis of randomised controlled trials in adults, the study was actually a review and meta-analysis of 30 randomized control trials involving almost 2,500 people who ate pasta instead of other carbohydrates.
The glycemic index, or GI, measures how a carbohydrate-containing food raises blood glucose when the food is eaten by itself. Foods are ranked on a scale of 0-100. The higher the number, the greater the effect.
The carbohydrates in foods with a high GI are quickly broken down into glucose and absorbed, leading to a rapid rise in blood sugar and a greater release of insulin, the hormone that moves glucose from the blood into cells, where it is used for energy. Eating foods with a low GI could, in theory, result in fewer spikes in blood sugar.
There are serious flaws with the glycemic index, but we will get to that later in this article.
Now let’s break down the study’s claims to try to figure out what’s really going on here.
Here’s what the authors stated in the Conclusion section of the study’s abstract.
Pasta in the context of low-GI dietary patterns does not adversely affect adiposity and even reduces body weight and BMI compared with higher-GI dietary patterns. Future trials should assess the effect of pasta in the context of other ‘healthy’ dietary patterns.
Pasta “in the context of low-GI dietary patterns” – that detail raises an important question:
Did the low glycemic diets do better because they included pasta, or despite pasta consumption?
The people involved in the clinical trials on average ate 3.3 servings of pasta a week instead of other carbohydrates. One serving equals about one-half cup of cooked pasta.
One-half cup of pasta is a small portion, so it is not surprising to hear that people who consume that amount 3 times a week may not necessarily be overweight. When was the last time you ordered pasta in a restaurant? In the US, pasta portion sizes are 2-3 times larger than they are in Italy – where a small portion of pasta is served as an appetizer or a side dish, not the main course. Think about the last time you had pasta. Did you only consume a half-cup?
Note that the study says the people involved in the clinical trials ate pasta “instead of other carbohydrates.”
From the press release:
They identified 30 randomized control trials involving almost 2,500 people who ate pasta instead of other carbohydrates as part of a healthy low-glycemic index diet.
Instead of WHAT other carbohydrates? What else did the people who were studied eat? We are not provided with that information. All we are told is that the people studied were eating “healthy low-glycemic diets”.
The study says people lost 0.63 kilograms (1.39 pounds) more than those on the high-glycemic diets without pasta.
Why did this study compare people who ate low-glycemic diets with those who ate high-glycemic diets? If the researchers really wanted to find out if pasta contributes to weight gain or weight loss and pasta’s role in all of this, wouldn’t it have made sense to study people who ate low-glycemic diets that included pasta and those who ate low-glycemic diets without pasta instead? What did the people on the high-glycemic diets eat?
Again, we don’t know what the people on either kind of diet was eating, or how much, or if they exercised regularly…or ANYTHING else.
The study says there was a slight decline in BMI with the low-glycemic diet, but no other measures of body fat changed.
There are several problems here. For starters, BMI is not a good tool for measuring weight or body fat – it is a simple height-to-weight ratio, and does not take into consideration one’s body composition. Athletes and bodybuilders with low body fat often are labeled as overweight or even obese on the BMI scale because they carry a lot of muscle.
In addition, one study found that a low BMI and high body fat percentage are independently associated with increased mortality in both men and women. Having a lower BMI isn’t necessarily a good thing! So, using BMI as a health measure for this study was not an optimal choice.
If the researchers didn’t explore how pasta impacts weight specifically, why is it the supposed topic of their study?
The researchers admit they didn’t look at pasta specifically!
Here’s what they wrote in the Strengths and Limitations section of the study:
None of the available trials evaluated the effect of pasta alone or in the context of other dietary patterns. Whether the observed effect of pasta in the context of low-GI dietary patterns will hold in the context of other healthy dietary patterns, such as Mediterranean and vegetarian dietary patterns, is unclear.
Instead, they decided to look at studies testing the effect of a low-glycemic diet (that included pasta) compared to a higher-glycemic diet. Again – this doesn’t make sense.
The glycemic index has a lot of flaws, so why did the researchers use it?
The study failed to mention the flaws associated with the glycemic index:
- It only applies when you eat the food in isolation.
- Adding starch, sugar, or fiber alters the GI of a food.
- So does adding fat, protein, salt, or organic acids (like vinegar), and so does chewing food longer.
- GI changes with food preparation.
- There are variations in glycemic response among people who eat the same food. University of Toronto scientists found that the value can vary by 23 percent to 54 percent from person to person. It can even vary within the same person!
- A slice of chocolate cake has a lower GI (54) than an apricot (82), an orange (60), a cup of strawberries (57), or a cup of watermelon (103).
What kinds of pasta did the study participants eat? Did they eat the pasta by itself, or was it served with other foods? How was the pasta cooked? All of these things matter – a lot. It is safe to assume the study didn’t consider those factors, because they were not mentioned at all in the paper.
Was this study even worth conducting?
In the study’s Conclusion, the authors state:
Although the clinical significance of the observed weight loss is debatable, this finding increases our confidence that pasta in the context of low-GI dietary patterns does not result in weight gain.
I’m sorry, but…what?
I have read that blurb at least five times and I can’t figure out one thing…
What was the point of this “study”?
Dr. John Sievenpiper, the study’s senior author, said of his “research”:
“We work in the areas of carbohydrate quality, doing randomized trials on glycemic index and plant-based diets that are higher in carbohydrates. And we’re seeing a lot of anti-carbohydrate sentiment and a real attack on carbohydrates, in particular a lot of the staples, like rice and bread and pasta.
So we wanted to test the question, ‘Does (pasta) have an adverse effect as suggested by the headlines and blog posts, and some of the expert opinions that you once find both in social and conventional media on this?’”
Maybe there’s an underlying (and sneaky) reason this research team decided to look into this “pasta” thing…
Some of the authors have received prior research grants, in-kind donations of pasta for a randomized controlled trial, and travel support from the pasta maker Barilla.
Take a look at the “competing interests” disclosure at the bottom of the study, and you’ll see “Barilla” mentioned more times than you’ll care to count.
Now, just because a study is funded by an industry or company that stands to benefit from results in their favor doesn’t mean the research itself is flawed.
But it IS worth consideration, especially when a study makes claims that sound suspicious, or if the study itself is filled with holes or is missing critical information.
When he was interviewed for that film, he was asked about industry-funded studies.
Here’s what he said:
DR. SIEVENPIPER: Part of the reason we have so much industry funded research is because the
governments have pulled back so much on their research budgets. And you know, academics, as
much as people wanna believe that they’re biased, they- they- they wanna do good research, and
they wanna do research. And if they can’t get the money to do- answer the important questions as
they see them, uh in their labs and clinics, from the government, then they will look to other
Text on Screen: The food industry continues to provide grants for sugar research to scientists,
including Dr. Sievenpiper. (source)
Follow the money.
By the way, this isn’t the first time Barilla has given scientists dough for studies. In 2016, the pasta company helped fund a “study” that conveniently found that pasta doesn’t “cause” obesity. That study was flawed too, and the media ran headlines about it that were terribly misleading (“Don’t Skip the Spaghetti! New Study Says Pasta Not Fattening” is one actual example).
The Bottom Line…
If something seems too good to be true, it probably is. Nutrition studies are, by nature, hard to conduct and are often flawed. View sensational headlines that make bold proclamations with a skeptical eye. Seek out various sources of information. Wait for more information before making big decisions about your health.
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