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

71–80 of 470 posts

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

#71

Post by jjcob »

varispeed wrote: post #56
jjcob wrote: post #52

Earlier quoted context omitted.

I've done that for weight loss, so I focussed on calories only. That was pretty easy: - while cooking, you weigh every ingredient. Either I just take photos of the scale with my phone, or I write it on a sheet of paper. - when cooking is done, you weigh the total food (easiest if you know the weight of your pots) - when eating, you weigh your portions After some time, you realise that you need to be precise for some…

How do you calculate calories?

Some foods I know, eg. oil 9kcal/g, but mostly I just check the label. Every food in the EU has the calories/100g or calories/100ml on the label. If it's not packaged, I look it up it FDDB [1].

[1]: https://fddb.info/db/de/produktgruppen/produkt_verzeichnis/i...

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

#73

Post by manfre »

FriedrichN wrote: post #21
elektrolite wrote: post #11

Earlier quoted context omitted.

I think being consistently inaccurate helps. If you always get the same thing at a certain restaurant, you can start by giving your best estimate of the calories in that meal. Then if your average weight doesn't move in the direction you want you can adjust your target calories to compensate.

That probably doesn't work either unless they work in an automated fashion. Did the chef put two or three dashes (official SI unit) of this or that on your meal? A a "dash" or "splash" or "spritz" of certain things can easily mean 100-200 kcal. And if you deal with things like meat, maybe the cut you get today is more or less lean than what you got last week. I think tracking calories for a couple of weeks can be ver…

Healthy foods are not healthy in an excessive quantity. Diets don't need to be tracked to the individual calorie. We don't burn the same amount l number of calories each day and food labels show an average of the nutritional value. If a person is consistent, they will achieve the desired result; either gaining or losing weight.

I've been tracking consistently for about 5 years. It's feasible.

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

#74

Post by jona-f »

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…

Well, caloric value isn't that exact to begin with, so there is no point in being overly exact. Afaik it's derived by burning the food and measuring the heat it produces, but your body doesn't burn it (like pyrolysis), it uses specialized proteins. So the energy conversion varies, some can't be digested at all.

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

#75

Post by FredPret »

We're far too generous with what we allow to be called "science".

There is no dietary research, because you can't pull off an unbiased dietary study over a meaningful period of time. Practical and ethical problems abound.

Maybe one day we can simulate n=10mm people from the neck down for a period of 30 years, and feed half of them bacon and half of them beans, but even that will have the major problems of being a simulation and that only from the neck down.

Read the original "fat = heart attacks" studies by Ancel Keys from the 1950's. I've done free online 5-minute long data science tutorials with more statistical rigor.

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

#76

Post by abhaynayar »

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…

What I did is just get a rough estimate of calories of things I'm eating. Along with tracking weight every day. Then over a couple of weeks, calibrated calorie estimates with recorded weight changes. Developed an intuition.

After that, I never looked up another calorie, and counted based on how the food felt, and basically lost exactly 0.5 kg/week over a period of 5 months. (500 kcal deficit/day).

Even if I'm wrong for a particular meal, the over/under-estimates must be cancelling out. My food situation makes it extremely hard to actually calculate calories, so I had to develop this skill.

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

#77

Post by Retr0id »

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…

I don't, but what I did do was track everything obsessively in a spreadsheet for about a week, while exercising and eating and sleeping a nominally correct amount. As you indicate, it's a lot of manual effort to track everything like that, and I couldn't see myself doing it long term.

But over that week, I "calibrated" myself. I know, vibe-wise, how it feels to be eating the correct amount of food. And now I just keep doing that.

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

#79

Post by _dark_matter_ »

FredPret wrote: post #75

We're far too generous with what we allow to be called "science". There is no dietary research, because you can't pull off an unbiased dietary study over a meaningful period of time. Practical and ethical problems abound. Maybe one day we can simulate n=10mm people from the neck down for a period of 30 years, and feed half of them bacon and half of them beans, but even that will have the major problems of being a sim…

There are ALL kinds of things we can't run experiments on. Climate, society, evolution, tech development, surgery, and more. We don't throw our hands in the air and say "science here is impossible!". Instead we roll up our sleeves and develop more and better causal inference models that improve over time.

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

#80

Post by BoxFour »

OkayPhysicist wrote: post #67
BoxFour wrote: post #34

Earlier quoted context omitted.

Why would that be a problem for reporting relative results if everyone is under-reporting things they're embarrassed about and over-reporting the opposite?

Different people are embarrassed by different things. A frat student's probably going to overstate their alcohol consumption, a Morman understate. People with bigger appetites underestimate their food consumption, people with smaller appetites overstate. Not to mention the degree of over/under statement will vary wildly. "A big meal" might be 300 calories for somebody with an eating disorder, or 3000+ for somebody on…

Sure, but in a representative sample size this is largely irrelevant. The fraternity brothers and the Mormons cancel each other out, and regardless both are dwarfed by the large middle of the population that likely systematically and reliably under-reports their drinking by a few units.

The idea of outliers and systematic biases isn’t new to statistics, relative comparisons are still useful.

Post reply on HN