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People are bad at reporting what they eat. That's a problem for dietary research

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Re: People are bad at reporting what they eat. That's a problem for dietary research

#161

Post by zeroonetwothree »

LPisGood wrote: post #132
wnorris510 wrote: post #130

I've done research in this space for many years at Google AI and now at SnapCalorie. The thing I find interesting is how confident people are in their ability to estimate portion size visually, and in truth how wrong they all are. We published in CVPR (top peer reviewed academic conference for computer vision) and people are on average off by 53% and even trained professionals are still off by 40%. Basically if you w…

>and even trained professionals are still off by 40% I find this very hard to believe, unless the term “trained professional” is quite broad. When I was much more into fitness and weighed every meal to the gram, I could tell if a bowl of cereal was a serving to within a gram or two.

If you read the paper it’s pretty easy to see what they mean by this. They tested “4 professional nutritionists”. I don’t know if nutritionists get any special training at estimating portion size but my guess would be they do not.

Re: People are bad at reporting what they eat. That's a problem for dietary research

#162

Post by onlyrealcuzzo »

lt_snuffles wrote: post #113

I feel bad for suggesting this, but what about using prison population for researching dietary science? Every single part of their life is controlled. As long as it's humane (stuff like coffee vs no coffee).

They're not guaranteed to eat what they are served - unless you're going to do force feeding as well.

So it's still not great.

Re: People are bad at reporting what they eat. That's a problem for dietary research

#163

Post by bluGill »

augustk wrote: post #107
llm_nerd wrote: post #89

Earlier quoted context omitted.

Such studies do exist - randomized feeding trials. In these studies the participants are provided all meals and snacks, and sometimes are under constant surveillance for weeks and sometimes months on end. https://pubmed.ncbi.nlm.nih.gov/39134209/ Obviously such studies are far more invasive and expensive to run than the classic "fill out of a survey" observational study [1], so they tend to be the outliers. But they…

Prisons seem like good places to make these kind of studies.

Prisons give you the control needed, but prisons generally are not realistic to how people could live their lives. When you are locked in a cell most of the day that limits movement (in ways different from an office where people get up to go to meetings and the like). Prisons will get you your 20 minutes a day of exercise, but it isn't representative of how most people will exercise (even counting only those who go to the gym). As such you can get a lot of data but it is unknown which data applies to normal people who live lives in ways that are likely different in ways that matter.

Re: People are bad at reporting what they eat. That's a problem for dietary research

#164

Post by wnorris510 »

ses1984 wrote: post #137
LPisGood wrote: post #132

Earlier quoted context omitted.

>and even trained professionals are still off by 40% I find this very hard to believe, unless the term “trained professional” is quite broad. When I was much more into fitness and weighed every meal to the gram, I could tell if a bowl of cereal was a serving to within a gram or two.

Isn’t that a bit of a special case because you know your cereal and you know your bowls? What about some cooked foods like meats which can vary in density and shape when raw, and also vary even further due to inconsistency in cooking, with more or less moisture cooked off? It’s possible to calibrate your estimates, but if you haven’t done that, it’s probably safe to assume you’re not particularly accurate.

There is definitely a lot of variation in density, moisture content, fat percentage between regions, cuts, cooking amounts and methods. IMO using an average number here is probably best because to some extent it's hopeless to account for all of these things.

Most people don't stay consistent in tracking long enough for any of this to matter, so really it's about what is the most accurate approach to achieve your goal and sustain longer term.

Re: People are bad at reporting what they eat. That's a problem for dietary research

#165

Post by amanaplanacanal »

BoxFour wrote: post #3

Does this actually pose an issue for most studies? This seems like it would be an issue for any studies relying on absolute food consumption being accurate. Most studies I come across frame their findings in relative terms (likely for this very reason): Individuals who engage in more of X compared to their peers show a correlation with outcome Y. For example, if you’re trying to determine whether morning coffee consu…

But finding correlations is only the first and easiest step in determining causation. And almost nobody continues with the hard work that follows. So we have tons of studies showing correlations one way or the other, and tons of conflicting studies. And we are apparently satisfied with this. The state of nutrition research is abysmal.

Re: People are bad at reporting what they eat. That's a problem for dietary research

#166

Post by vladvasiliu »

taeric wrote: post #153
wnorris510 wrote: post #130

I've done research in this space for many years at Google AI and now at SnapCalorie. The thing I find interesting is how confident people are in their ability to estimate portion size visually, and in truth how wrong they all are. We published in CVPR (top peer reviewed academic conference for computer vision) and people are on average off by 53% and even trained professionals are still off by 40%. Basically if you w…

This goes a long way to further convince me that it is portion sizes in the US. Having traveled, it is quite absurd to see the difference in standard order sizes. Even for zero calorie things like water and unsweetened teas/coffees. You just get smaller cups. I'm not even sure you can get a US large in Japan for most drinks?

Probably depends on where you go.

I don't know about "the US", but as a "European" I thought serving sizes were comparable to what I get in restaurants at home. Drinks were an exception, since basically all restaurants had unlimited soda for next to nothing. This was actually great, since I was riding a motorbike in the desert in July.

For reference, I live in France and visited LA and random towns in the western states.

Re: People are bad at reporting what they eat. That's a problem for dietary research

#167

Post by bluGill »

dnpls wrote: post #135
tzs wrote: post #116

Earlier quoted context omitted.

This won't be useful for you because you share food with others, but for people who do not share food and are interested in long term tracking rather than short term (e.g., they want to take off some weight at a healthy rate and keep it off, as opposed to people who just want to lose a few pounds rapidly for their class reunion and will make no effort after that to keep it off) there is a simple trick that can make i…

A jar of mayonnaise?? you can measure by the spoonful (or better, by weight, since its nutritional value is in the package) whenever you eat. A month is a long time and the measurement error will accumulate every day, especially with fats. Not so much problem if you do that with cucumber or spinach.

> A month is a long time and the measurement error will accumulate every day, especially with fats

Over several months the errors will average out. Unless you eat out a lot, then the above method doesn't work. However if you are single (this is the most unlikely factor!) and cook most meals at home then calories in the door - what you throw away = calories that you ate. That is good enough.

Re: People are bad at reporting what they eat. That's a problem for dietary research

#168

Post by amanaplanacanal »

BoxFour wrote: post #58
liveoneggs wrote: post #49

Earlier quoted context omitted.

All of those headlines are based on meta-studies putting together 100 junk studies, based on bad data, which then informs actual medicine and health trends and American X Association and... For your specific example - "morning coffee" could be anything from plain espresso shot to full 600+ calorie starbucks "coffee" but the meta-study-machine will lump them together. It's kind of like feeding all of reddit's comments…

> "morning coffee" could be anything from plain espresso shot to full 600+ calorie starbucks "coffee" but the meta-study-machine will lump them together. You're inadvertently proving my point, though. If morning caffeine is correlated with longevity, regardless of the vehicle/extra sugar/etc and controlling for the easy usual circumstances like income, that's pretty useful information!

It might be useful information for other researchers to try to figure it what is actually going on, but probably not. And it is not at all useful for you and I trying to make sense of what we should eat.

Re: People are bad at reporting what they eat. That's a problem for dietary research

#169

Post by wnorris510 »

zeroonetwothree wrote: post #161
LPisGood wrote: post #132

Earlier quoted context omitted.

>and even trained professionals are still off by 40% I find this very hard to believe, unless the term “trained professional” is quite broad. When I was much more into fitness and weighed every meal to the gram, I could tell if a bowl of cereal was a serving to within a gram or two.

If you read the paper it’s pretty easy to see what they mean by this. They tested “4 professional nutritionists”. I don’t know if nutritionists get any special training at estimating portion size but my guess would be they do not.

Some do, some do not. We put them through a standard portion size training course regardless to be sure.

Re: People are bad at reporting what they eat. That's a problem for dietary research

#170

Post by stevesimmons »

taeric wrote: post #153
wnorris510 wrote: post #130

I've done research in this space for many years at Google AI and now at SnapCalorie. The thing I find interesting is how confident people are in their ability to estimate portion size visually, and in truth how wrong they all are. We published in CVPR (top peer reviewed academic conference for computer vision) and people are on average off by 53% and even trained professionals are still off by 40%. Basically if you w…

This goes a long way to further convince me that it is portion sizes in the US. Having traveled, it is quite absurd to see the difference in standard order sizes. Even for zero calorie things like water and unsweetened teas/coffees. You just get smaller cups. I'm not even sure you can get a US large in Japan for most drinks?

Portion sizes in the US are ridiculous... often 2-3x larger than here in Europe.

When I regularly visited New York for work, and we'd get takeaway sandwiches, I'd have to open them and remove half the filling. I just couldn't physically eat that volume of meat, cheese or especially mayonnaise. For all drinks, I'd order small.

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