Author Topic: The anecdote in diet  (Read 2325 times)

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Online bachfiend

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The anecdote in diet
« on: December 15, 2018, 08:40:58 PM »
It’s often written that the plural of ‘anecdote’  isn’t ‘data.’  And that anecdotes are useless as evidence.  And that clinical trials of diets are the only way of determining which diets work, and which ones don’t, and which ones are ‘best.’

Anecdotes actually are very useful.  They indicate which diets and strategies actually worked for at least one person. 


The best diet for a person is the one a person can keep to for years and decades.  Clinical studies of diet suffer from the drawback that they’re short term, limited to 6 or 12 months usually.  Clinical studies also aren’t in the ‘real world.’  The participants usually are receiving more counselling than usual, and the participants are often more ready to comply with the diet in order to please the investigators.

Colby Vorland on nutrition.org has written an interesting article.

https://nutrition.org/the-appropriate-evaluation-of-the-anecdote/

I argue that if you collect enough anecdotes, then you potentially have a long term observational study.  That the plural of anecdotes is data, and very useful data.
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Offline Harry Black

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Re: The anecdote in diet
« Reply #1 on: December 15, 2018, 09:03:58 PM »
Anecdotes are actually not very useful. At all.

If you collect anecdotes as people collect stamps then you will surely go wrong.
If you collect them as an actual scientist, tracking trends and controlling as much as one can for bias and methodology then it becomes a study.
All an anecdote tells you is one persons perspective on what happened to them.

Online bachfiend

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Re: The anecdote in diet
« Reply #2 on: December 15, 2018, 09:28:06 PM »
Anecdotes are actually not very useful. At all.

If you collect anecdotes as people collect stamps then you will surely go wrong.
If you collect them as an actual scientist, tracking trends and controlling as much as one can for bias and methodology then it becomes a study.
All an anecdote tells you is one persons perspective on what happened to them.

Well, there are anecdotes and there are anecdotes.  Some anecdotes are useless, being little more than ‘I went on diet x, and lost y kg in z months.’  Others are more useful, being virtually mini-autobiographies, detailing experiences and problems with particular diets.

Anecdotes have to be taken with a grain of salt.  As too do clinical studies.  Not all clinical studies or peer reviewed papers in journals are ‘true.’  All studies have some flaws.  And it’s a greater mistake to extrapolate from a clinical study, no matter how good, to think it’s giving an answer to a question it wasn’t asking.  For example, long term results from short term studies.
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Offline Harry Black

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Re: The anecdote in diet
« Reply #3 on: December 15, 2018, 09:39:52 PM »
Thats a kind of relativism I just cNt get on board with.
Sure, lots of studies have flaws and will get refuted.
But to say they are in any way comparable to anecdotes where people talk about how great the blood type diet or whatever is, is ridiculous.

Online bachfiend

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Re: The anecdote in diet
« Reply #4 on: December 15, 2018, 10:05:21 PM »
Thats a kind of relativism I just cNt get on board with.
Sure, lots of studies have flaws and will get refuted.
But to say they are in any way comparable to anecdotes where people talk about how great the blood type diet or whatever is, is ridiculous.

As I said, there are anecdotes and there are anecdotes.  And there are diets of varying degrees of respectability.  A recent popular fad diet is the low carbohydrate/high fat ketogenic diet.  Another one are the various forms of intermittent fasting.  Anecdotes regarding these can be useful, but not necessarily. 

All that clinical trials on diet can show is that on average in the short term they worked, nothing more.

You should only consider anecdotes about acceptable long term diets.  I wouldn’t put the blood type diet (or the fruit diet, or whatever) into that group.  And I would also reject the Paleo diet too, since no one knows what preagricultural hunter-gatherers were actually eating.

It seems as though you’re not not interested in discussion, just rejecting anecdote as evidence, automatically.
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Offline Harry Black

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Re: The anecdote in diet
« Reply #5 on: December 15, 2018, 10:18:20 PM »
I think anecdotes are a great reason to look for more data and if data is not available, I would hope that a sufficient number of anecdotes might inspire someone to investigate and get us more data.
But I dont think they are a good enough basis to make lifestyle changes.
As I have said before, almost every great specimen I know has some pretty ridiculous and conflicting ideas as to why they are so.
By being here I am having a discussion. I just dont agree with you and you arent convincing me so far.

Online bachfiend

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Re: The anecdote in diet
« Reply #6 on: December 15, 2018, 10:47:28 PM »
I think anecdotes are a great reason to look for more data and if data is not available, I would hope that a sufficient number of anecdotes might inspire someone to investigate and get us more data.
But I dont think they are a good enough basis to make lifestyle changes.
As I have said before, almost every great specimen I know has some pretty ridiculous and conflicting ideas as to why they are so.
By being here I am having a discussion. I just dont agree with you and you arent convincing me so far.

Agree with much of which you say.  Anecdotes aren’t a good enough basis to make lifestyle changes, but they can be a good enough basis to decide which lifestyle changes could be considered if lifestyle changes are necessary - for example if a person is overweight or obese, or very sedentary.

And it’s usually obvious rapidly if the lifestyle changes are working or not, giving the person the opportunity to try something else.

Diet isn’t in the same category, as for example, ‘alternative’ therapy for cancer, regarding which I wouldn’t take any notice of anecdotes.
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Offline Harry Black

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Re: The anecdote in diet
« Reply #7 on: December 16, 2018, 05:42:48 AM »
Take notice. But what are you going to do with it? The stakes arent really that high but if you have a goal, you want to give yourself the best chance of achieving it no?
The effect of diet on the body is usually a ship that takes a long time to stop or turn around, so you could potentially get no closer to your goals for a couple of years if you go through a few different anecdotes that dont pay off.
Its hard enough even if you are following well tested advice and then, the advice is pretty mundane and unsurprising.
If trying those things is interesting to you then great, but I wouldnt expect it to be convincing to anyone else.

Offline daniel1948

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Re: The anecdote in diet
« Reply #8 on: December 16, 2018, 09:48:41 AM »
... And I would also reject the Paleo diet too, since no one knows what preagricultural hunter-gatherers were actually eating. ...

Indeed, nobody knows what prehistoric people were eating, except that in different areas they were eating different diets, so there is no one “paleo” diet. However, any diet characterized by its practitioner as “paleo” would give just as valid anecdotes as any other diet that someone stayed on long-term. One would just have to be careful not to conflate that diet with all the other variations of “paleo” diets.

But I’d like to illustrate the weakness of anecdotal evidence with a personal story: In my 20’s I was so overweight that I was afraid to get on a scale and find out how heavy I was, and I’d failed on a series of diets, when I decided to try a “diet” of my own devising: I allowed myself to eat all I wanted of most foods, but I prohibited myself from eating anything from any of four food types which are trigger foods for me, that I could not eat in moderation: nuts, dried fruits, pasta, and baked sweets such as cake and cookies. Whenever I ate these things I ate way too much. I began to lose weight and reached the middle of the healthy weight range for my height. The charts say that for a 5’ 6” person, the healthy range is from 120 to 140 pounds. I got to 130 pounds. My diet worked, anecdotally.

A few months after reaching this weight an employer commented that I looked sick and insisted that I see a doctor. He was so emphatic about it that I did. It turned out that I had become hyperthyroid. I was losing weight in spite of my “diet,” not because of it. I got radioactive iodine treatment for my thyroid and then began gaining weight again, while still on my “diet.” That was when I began exercising and adopted a healthier diet with the advice of my doctor. With a healthy balanced diet and exercise I got my weight back down, and it remained low for a number of years until I made some bad lifestyle choices. (Since corrected.)

My anecdote was useless, even though it spanned a considerable length of time, because I was not able to account for a factor unrelated to my list of approved foods.
Daniel
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Online bachfiend

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Re: The anecdote in diet
« Reply #9 on: December 16, 2018, 02:30:04 PM »
... And I would also reject the Paleo diet too, since no one knows what preagricultural hunter-gatherers were actually eating. ...

Indeed, nobody knows what prehistoric people were eating, except that in different areas they were eating different diets, so there is no one “paleo” diet. However, any diet characterized by its practitioner as “paleo” would give just as valid anecdotes as any other diet that someone stayed on long-term. One would just have to be careful not to conflate that diet with all the other variations of “paleo” diets.

But I’d like to illustrate the weakness of anecdotal evidence with a personal story: In my 20’s I was so overweight that I was afraid to get on a scale and find out how heavy I was, and I’d failed on a series of diets, when I decided to try a “diet” of my own devising: I allowed myself to eat all I wanted of most foods, but I prohibited myself from eating anything from any of four food types which are trigger foods for me, that I could not eat in moderation: nuts, dried fruits, pasta, and baked sweets such as cake and cookies. Whenever I ate these things I ate way too much. I began to lose weight and reached the middle of the healthy weight range for my height. The charts say that for a 5’ 6” person, the healthy range is from 120 to 140 pounds. I got to 130 pounds. My diet worked, anecdotally.

A few months after reaching this weight an employer commented that I looked sick and insisted that I see a doctor. He was so emphatic about it that I did. It turned out that I had become hyperthyroid. I was losing weight in spite of my “diet,” not because of it. I got radioactive iodine treatment for my thyroid and then began gaining weight again, while still on my “diet.” That was when I began exercising and adopted a healthier diet with the advice of my doctor. With a healthy balanced diet and exercise I got my weight back down, and it remained low for a number of years until I made some bad lifestyle choices. (Since corrected.)

My anecdote was useless, even though it spanned a considerable length of time, because I was not able to account for a factor unrelated to my list of approved foods.

If you were hyperthyroid you would have had other symptoms other than losing weight.  Such as heat intolerance and anxiety.  One patient I saw was so anxious, i was considering sending her to a psychiatrist, until I thought I’d better exclude hyperthroidism. 

Around 2005, i developed the reverse problem and became hypothyroid, and i put on weight, despite my diet and exercise program.  The penny dropped when I turned up for work one morning in March wearing 3 jackets (the temperature was 8.3 degrees Celsius which is cold for Perth in March) and one of my colleagues asked me why I was wearing three jackets, and I answered that I feel the cold, and that I must have a slow metabolism, and i suddenly realised, and rushed off and had a thyroid function test.

Anecdotes include how the person feels on their diet.  I doubt seriously that you would have felt well losing weight.  Your anecdote is actually very useful if you’d expanded it.  What was the healthier diet and exercise program your doctor advised for you to adopt for you to lose weight?  What were the subsequent bad lifestyle choices that caused you to put the weight back again?

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Offline daniel1948

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Re: The anecdote in diet
« Reply #10 on: December 16, 2018, 03:37:01 PM »
I was not aware of any symptoms other than weight loss, which I was trying to achieve, so attributed wrongly to my diet. In retrospect I was more tired than usual, but since I was not in good physical condition until much later, when I began jogging, I didn’t really notice that I was more tired. My pulse was greatly elevated, but I was unaware of that as I’d never been in the habit of taking my pulse, and probably didn’t even know what a normal pulse was. Apparently my eyes were bulging, but I was not aware of that either. But when I went to the doctor he diagnosed it immediately. Apparently I was a classic case. But I was not aware of feeling any differently. I never liked heat, but I was not aware of being more sensitive to it.

My doctor pretty much just advised me to eat a balanced diet and cut down on dairy fat, which I’d been consuming a lot of. In those days I worked on a dairy farm and got my milk there. It was 3.75% butterfat. Standard whole milk is 3.5%. I made it into chocolate milk and drank a gallon about every two days. And in those days my staple main dish most days was pizza with typically half a pound of aged cheddar cheese (much better than the conventional mozzarella.)

The lifestyle screw-up a decade later is a different issue for a different post. While I continued exercising and healthy eating I maintained my weight for a decade and felt very healthy. In those days I jogged 21 miles a week. I cannot do that any more, but now I paddle most mornings.
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Online bachfiend

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Re: The anecdote in diet
« Reply #11 on: December 16, 2018, 03:58:59 PM »
I was not aware of any symptoms other than weight loss, which I was trying to achieve, so attributed wrongly to my diet. In retrospect I was more tired than usual, but since I was not in good physical condition until much later, when I began jogging, I didn’t really notice that I was more tired. My pulse was greatly elevated, but I was unaware of that as I’d never been in the habit of taking my pulse, and probably didn’t even know what a normal pulse was. Apparently my eyes were bulging, but I was not aware of that either. But when I went to the doctor he diagnosed it immediately. Apparently I was a classic case. But I was not aware of feeling any differently. I never liked heat, but I was not aware of being more sensitive to it.

My doctor pretty much just advised me to eat a balanced diet and cut down on dairy fat, which I’d been consuming a lot of. In those days I worked on a dairy farm and got my milk there. It was 3.75% butterfat. Standard whole milk is 3.5%. I made it into chocolate milk and drank a gallon about every two days. And in those days my staple main dish most days was pizza with typically half a pound of aged cheddar cheese (much better than the conventional mozzarella.)

The lifestyle screw-up a decade later is a different issue for a different post. While I continued exercising and healthy eating I maintained my weight for a decade and felt very healthy. In those days I jogged 21 miles a week. I cannot do that any more, but now I paddle most mornings.

If you were reporting your anecdote regarding your ‘successful’ weight loss on your diet, you would have been a little more introspective about how you actually felt on your diet, and perhaps the penny might have dropped earlier, instead of your boss expressing concern about your health, and insisting that you ought to see your doctor.

And anyone reading your anecdote would either realise that your ‘diet’ wasn’t for them, or if they tried it, wouldn’t have any success, and abandoned it quickly.

There are anecdotes, and there are anecdotes.  Some anecdotes are better than others.
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Offline daniel1948

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Re: The anecdote in diet
« Reply #12 on: December 16, 2018, 07:53:38 PM »
Back then I don’t think I’d have been any more introspective. And in fact, I did “report” my diet, in the sense that I told people about it. And while my list of trigger food groups was specific to me, the concept of eliminating your own trigger foods sounded reasonable to me, and very well might have sounded reasonable to others. The internet didn’t yet exist, or at least not in a form open to the general public. A person inclined to regard anecdotes as data could well have taken my diet seriously. My employer figured out that there was something wrong with me, and my doctor diagnosed it immediately, but nobody else of all the people I saw on a regular or irregular basis spotted anything wrong with me.

People believe in pseudoscience because they regard anecdotes just like mine as meaningful.
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Offline John Albert

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Re: The anecdote in diet
« Reply #13 on: December 16, 2018, 07:58:12 PM »
The best diet for a person is the one a person can keep to for years and decades.

I could easily live on nothing but junk food and alcoholic beverages for at least a few decades. That doesn't mean it would be a 'healthy' or beneficial diet.

Offline Harry Black

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Re: The anecdote in diet
« Reply #14 on: December 16, 2018, 08:19:20 PM »
Saying that some anecdotes are better than others is both a true and meaningless statement.
By what standard to we evaluate their merit? As skeptics, who do we promote a more robust standard of epistemology while telling people to effectively go with their gut on random anecdotes?
And to be clear, gut is all it is because its far easier to post hoc make an anecdote fit our purposes than a more rigorous body of data.
Why on earth would we need to move to anecdote when we have pretty good data anyway? 

 

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