Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

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

science.org

Post reply on HN
Print view View original

131–140 of 470 posts

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

#131

Post by dnpls »

beezlebroxxxxxx wrote: post #70
aziaziazi wrote: post #29

For those that "track and weight everything" (how ?) do you manage ?: - sauces you make yourself? I often mix some different oils, mustard, seeds, miso, bit of leamon juice and spices… but weighting and logging everything will take 3x the time to do the sauce itself - different cooking time in one receive : oignons going first, tomato sauce in the middle and parsley at the end (but still cook a bit with residual heat…

Counting works for people because it quantifies their food intake. For many people, that's an effective way to overcome a learned idea that portions should be huge, or that feeling hungry has to be addressed immediately, or that feeling "full" has to be constant. It's not perfect, and I don't recommend it to people with an ED history; however, after about a month or 2 of doing it, it can really change how you look at…

This is it. There will always going to be impossibly unpredictable errors even if you measure everything perfectly.

The point of measuring is to be * as accurate as possible *, not 100% error-free. It helps to better estimate portion sizes, calorie / macro amounts. This is enough precision to control weight gain / loss correctly.

A lot of people also get their maintenance calories estimation wrong, so it doesn't matter if you can measure your food down to the molecules but still eat too much / too little.

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

#132

Post by LPisGood »

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.

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

#133

Post by tomrod »

lm28469 wrote: post #41
tomrod wrote: post #23

Earlier quoted context omitted.

You reduce the uncertainty of the remaining 20 by substantially increasing sample size across a randomly selected sample. Unfortunately for these studies you have multiple selection criteria that are nonrandom: (1) interest in the study (2) adherence to protocol of the study (3) reporting back in If nutrition science wants to be serious, their N should not be in the 10s but rather the 10,000s. That has an expense, bu…

Until they track absolutely everything including each trial subject microbiome, hormone profile, &co over time, I still feel it just won't cut it. Plus it doesn't even matter what is true for the statistical average, given the infinite amount of variables and outcomes one glass of wine might be statistically beneficial but absolutely terrible for your own health because you have one specific gene combination or one s…

Actually, this is why stats exists in the first place. Larger samples (including metastudies) are so powerful -- you can measure and predict causal impact of test factors even if you can't control for unobservables. The goal is to minimize type 1 and type 2 error. So long as those unobservables are not driving a selection bias, you get wonderful things like the central limit theorem coming to the rescue.

No one can monitor or measure everything, whether philosophically (Heisenberg uncertainty principle) or prosaically (cost). But if something is true, we can often probe it enough to get at least a low-res idea of the nature of it. This moves us light years ahead of primarily using our personal experience, gut, and vibe to establish epistemologically sound assertions.

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

#134

Post by bluGill »

Havoc wrote: post #110

It’s also just really hard unless you live off packaged meals or only eat thing that are isolated. Something like a curry cooked in kitchen and shared among a family is a complete black box as to who got how many calories. Maybe one person got a different ratio of rice to curry. Or this family likes a sweeter type of curry etc

For an individual trying to lose weight this isn't a problem - if you are not losing then you just need to eat less. For population level trying to figure out if curry is healthy in the first place this matters though (is it curry itself that is good/bad, one of the spices, or how much sweetener added - if all we know is curry that isn't helpful)

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

#135

Post by dnpls »

tzs wrote: post #116
aziaziazi wrote: post #29

For those that "track and weight everything" (how ?) do you manage ?: - sauces you make yourself? I often mix some different oils, mustard, seeds, miso, bit of leamon juice and spices… but weighting and logging everything will take 3x the time to do the sauce itself - different cooking time in one receive : oignons going first, tomato sauce in the middle and parsley at the end (but still cook a bit with residual heat…

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.

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

#136

Post by JoeAltmaier »

People are bad at reporting ANYTHING. Exercise, food, sex, grooming. Just ask a lawyer or anybody trying to get a story out of somebody.

This should be a fundamental understanding of anybody asking people anything. That scientists imagine there's some accurately-reporting population of subjects for their experiment is an example of the breathtaking naivete of scientists.

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

#137

Post by ses1984 »

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.

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.

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

#138

Post by watwut »

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.

There is no profession that would require you to estimate portion sizes up to grams visually. So, trained professional will be someone who was trained in something different - a doctor for example.

I guess, maybe cooks should have the best precision for this.

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

#139

Post by m_ke »

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…

At Bitesnap we were surprised at how much interest there was from researchers to use our app for diet tracking. It turns out giving people a piece of paper to write “grilled cheese sandwich for lunch” is not a scalable and reliable way to collect research quality data.

We even worked with USDA on putting together a food logging dataset: https://agdatacommons.nal.usda.gov/articles/dataset/SNAPMe_A...

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

#140

Post by derbOac »

everdrive wrote: post #81

A lot of people seem to have a purely emotional relationship with resources which logic doesn't seem to be able to penetrate. Food and finances seem similar here. For years I tried to get my wife to stick to a grocery budget. That is, we have $n per week for all groceries. She'd blow badly over the limit every time. "But we needed [food]" or "These were toiletries, so they don't _count_ as groceries." Ultimately we n…

It's really hard (emotionally or motivationally) to undereat, which is what you need to do consistently for a long time to lose weight.

Aside from the hunger issue, food is enmeshed in all sorts of value having nothing to do with nutritional value per se and everything to do with sociopsychological value.

I think I've massively underestimated that in my own life, or misunderstood what that meant or something. I think the way it plays out is much more pervasive and subtle than what people realize. I'm not even saying it's wrong, it's just hard to suddenly deprive yourself of something that is meaningfully rewarding, and especially so when you're unaware of it consciously.

Post reply on HN