Pasta makes you slim? Correlation vs causation

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timmmay

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#198406 8-Jul-2016 08:40

In this story some Italian researches came to the conclusion that pasta is associated with (effectively) being slimmer. They worked this out with surveys - people who ate pasta were slimmer.

To me this seems to cause causation with correlation. Perhaps people who are already slim choose to eat pasta. Perhaps people who ate pasta felt guilty and went for a run. Or perhaps pasta really does help you stay slimmer.

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#1587942 8-Jul-2016 08:51

By the same logic you could conclude that 100% of people who are fat consume water, therefore water makes you fat.

Fred99

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#1587952 8-Jul-2016 09:05

Every day there seems to be some new clickbait story based on equally dodgy health "research" suggesting something equally wonderful..

The correlation which should be considered first when reading the news is "if it seems too good to be true = it probably isn't", even when it's not counter-intuitive. That one was extremely poor - IIRC there wasn't even a hint of scientific method and the participant's diet was self-reported.

Choose to start believing some of the stories, and you''re at risk of even believing that there really are "superfoods" and behaviours that'll prevent or cure every ailment known to mankind, we'll be able to bulldoze all the hospitals and plant organic blueberries on the land.

freitasm

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#1587954 8-Jul-2016 09:13

The Italian pasta industry in no way sponsored the study, sure...

Fred99

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#1587962 8-Jul-2016 09:25

freitasm:

The Italian pasta industry in no way sponsored the study, sure...

Barrilla Spa (world's largest pasta maker) sponsored the research through the MISE (Italian Ministry of Economic Development).

More is revealed in the "Neuromed" website. It shows that organisation is mainly staffed by extremely attractive models wearing lab coats, with stethoscopes, peering at petri dishes. It could be legit. Next life I want to be an Italian lab-geek.

andrew027

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#1587963 8-Jul-2016 09:26

That pasta study is wrong, and directly contradicts the findings of my own research. I've discovered that 100% of people over the age of six months who died in 2015 had eaten food at some point during their lives. The majority of them ate something every day, and often two or three times a day. I've therefore concluded that eating is fatal and if you never eat anything you'll live forever. My findings will be published in a reputable medical journal (Stuff's lifestyle section) next week.

robjg63

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#1587967 8-Jul-2016 09:28

Eating pasta (or anything) doesnt make you fat or slim.

Eating more than your body needs makes you fat.

Eating less than your body needs makes you lose weight.

OMG - I should claim a research grant!

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Fred99

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#1587972 8-Jul-2016 09:36

robjg63:

Eating pasta (or anything) doesnt make you fat or slim.

Eating more than your body needs makes you fat.

Eating less than your body needs makes you lose weight.

I don't believe it's quite as simple as that. I'm sure I eat well in excess of what I need (calorific intake) yet I'm slim (same weight, waist measurement as when I was 18 - almost 40 years ago).

Genetics surely play a major part - even if how you play the hand of cards fate delivered you makes a huge difference.

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#1587977 8-Jul-2016 09:47

andrew027:

That pasta study is wrong, and directly contradicts the findings of my own research. I've discovered that 100% of people over the age of six months who died in 2015 had eaten food at some point during their lives. The majority of them ate something every day, and often two or three times a day. I've therefore concluded that eating is fatal and if you never eat anything you'll live forever. My findings will be published in a reputable medical journal (Stuff's lifestyle section) next week.

Reminds me of this:

THE SCIENTIST AND THE FROG

Previous Next

There once was a scientist who studied frogs. One day, the scientist put the frog on the ground and told it to jump. The frog jumped four feet.

So the scientist wrote in his notebook, "Frog with four feet, jumps four feet."

So the scientist cut off one of one of the frogs legs. The scientist told the frog to jump. Frog jumped three feet. So the scientist wrote in his note book, "Frog with three feet, jumps three feet."

So the scientist cut of another leg. He told the frog to jump. The frog jumped two feet. So the scientist wrote in his notebook "Frog with two feet, jumps two feet."

The scientist cut off one more leg. He told the frog to jump. Frog jumped one foot. So the scientist wrote in his notebook, "Frog with one foot, jumps one foot."

So the scientist cut off his last leg.

"He said, "Frog jump. Frog jump. FROG JUMP!"

So the scientist wrote in his notebook, "Frog with no feet, goes deaf."

itxtme

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#1590963 13-Jul-2016 13:28

P hacking pure and simple

dipkiwi

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#1606343 8-Aug-2016 14:13

From the Stuff article...

"Not only did the study find no correlation between eating pasta and an unhealthy weight - it was the opposite, with pasta consumption being linked to being slimmer"

Here is the study in question.

From table 1.

Women normal weight group averages
Energy intake kcal per day; 2070
Waist circumference; 80.5 cm
Hip circumference; 95.4 cm
Pasta grams per day; 57.3

Women obese weight group averages
Energy intake kcal per day; 1964
Waist circumference; 105 cm
Hip circumference; 114 cm
Pasta grams per day; 59.2

***

Men normal weight group averages
Energy intake kcal per day; 2417
Waist circumference; 86.7 cm
Hip circumference; 96.0 cm
Pasta; 75.6 grams per day

Men obese weight group averages
Energy intake kcal per day; 2451
Waist circumference; 108 cm
Hip circumference; 110 cm
Pasta; 58.5 grams per day

So how come the study's conclusions and subsequent press headlines are saying the opposite of what they actually found? Apparently the authors of the study suspected some of the participants from the obese woman category had underreported what they eat because of the fewer calories compared to the normal weight women, so they decided just to make sh!t up instead.

Quote from the study...

"On the other hand, bias of over-estimation or under-estimation presented generally in dietary data was evident also in the present datasets especially in women. As a result, pasta intake expressed as grams per day, seemed to be positively associated with BMI in crude analysis. However, to overcome the related bias, the correction of food group consumption by total caloric intake using the 'energy residual methodology' was elaborated as a relatively frequent procedure in dietary analysis. The association changed direction and from positive became negative"

A wave of the magic wand and positive became negative. Yay for science!

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#1610834 12-Aug-2016 17:19

I agree, I read the article and it didn't seem very convincing to me.

linw

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#1611023 13-Aug-2016 08:30

Assuming causation from correlation is SO common, and it irks me a lot.

After very many years I still remember my first Uni Psych 1 lab where the tutor made us write 50 times, words to the effect that correlation says nothing about causation!

I've forgotten a lot of things over time but I hazard that will be one of the things I remember till the end

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#1611028 13-Aug-2016 09:01

Every time I turn on the telly NZ loses a sevens match.

TwoSeven

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#1611041 13-Aug-2016 10:03

To me, 2400 calories is quite a bit to be eating, it would imply that the normal person is doing a bit more exercise than the overweight person, and the age isn't given, nor is the muscle mass of each individual - it would be hard to know the average calory burn of each individual.

Also, 50 grams of pasta is about 70 calories, so roughly the same as a slice of bread. As a percentage of daily intake it's quite a small number. Also, different types of pasta have a different glycemic index and also glycemic response.

Finally, I don't think the mediterainian diet contains much in the way of carbs anyway, so having a small amount I think would probably not really have that much if an impact.

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#1611053 13-Aug-2016 11:52

we should do the survey on the 7s team right now

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