Speed of eating 'key to obesity'

http://news.bbc.co.uk/1/hi/7681458.stm

by chegra • 16 years ago

38 31 16 years ago

news.bbc.co.uk

I'd like to believe this, and have no real trouble doing so, but I've just spent the last several hours on activities that require me to be a complete sceptic, so here are some thoughts:

================================

The researchers have found a statistical link. What they haven't yet done is design a controlled experiment whose outcome is predicted by this apparent correlation and then done the experiment.

A UK nutrition expert says that problems in signalling systems which tell the body when to stop eating may be partly responsible. [emphasis mine]

He said deliberately slowing down at mealtimes might impact on weight. [emphasis mine]

Australian researchers ... said that a mechanism that helps make us fat today may, until relatively recently, have been an evolutionary advantage, helping us grab more food when resources were scarce. [What mechanism? No mechanism has been proposed.]

Dr Jason Halford ... said: "What the Japanese research shows is that individual differences in eating behaviour underlie over-consumption of food and are linked to obesity." [No, it showed there is a statistical link. Perhaps people who tend to be overweight have a drive to eat quickly.]

"Other research has found evidence of this in childhood, suggesting that it could be inherited or learned at a very early age." [What other evidence? No hint of references given, so we can't find out for ourselves.]

... there was no evidence yet that trying to slow down mealtimes for children would have an impact on future obesity rates. [So the one piece of experimental procedure that might really confirm this either hasn't been done, or doesn't support the conclusion.]

================================

Having said all that, when I lost weight recently I worked hard on eating more slowly, and I do feel that it helped me feel less hungry on my 1600 kCal/day "diet". My own experience would support the claims, but that's just anecdote.

It's not science, and neither is what the article reports. It's typical media.

chegra• 16 years ago

Yea, I realize it is alot maybe and mights in there. There is other studies but this was the best one in terms of explanation[media]. There was this study: http://www.independent.co.uk/life-style/health-and-families/... I didn't post it because the method didn't sound solid.

But it is almost zero cost method, so I said why not give it a go.

micheljansen2• 16 years ago

Keen observation. Correlation does not imply causation. Do keep in mind though that this is an old article (2008). Followup studies have been conducted, such as "Treatment of childhood obesity by retraining eating behaviour: randomised controlled trial", by Ford et al.: http://www.bmj.com/cgi/content/abstract/340/jan05_1/b5388

Quote: "Conclusions: Retraining eating behaviour with a feedback device is a useful adjunct to standard lifestyle modification in treating obesity among adolescents."

I have not read the whole article though, and some cautious scepticism is required as the authors seem to have commercial interests in the results :)

jules• 16 years ago

The mights don't really mean anything. This is just how scientists talk.

jquery• 16 years ago

Your first claim is not supported by your second. You might be wrong.

tel• 16 years ago

It's a style built out of a community of skeptics design to encourage further skepticism — so RoG is right on the money, right?

tokenadult• 16 years ago

It's not science, and neither is what the article reports. It's typical media.

That's why when I see a Hacker News thread posting a journalistic report about some preliminary scientific study, I link to Peter Norvig on how to read research

http://norvig.com/experiment-design.html

for the HN newcomers who haven't read this excellent article yet.

lionhearted• 16 years ago

> http://norvig.com/experiment-design.html

Best article I've read in a long time. That was amazing. I wish I could vote this comment up many times so that other people are sure to see it - I feel much, much more informed as a result of reading that.

Thank you.

goodside4• 16 years ago

There's an obvious alternative explanation here: Overweight people are generally hungrier than average. Hungrier people also tend to eat faster. Eating speed does not cause obesity, but correlates with it because it proxies a general propensity toward hunger.

Still, I suspect the article's conclusion is at least partially right, even if it's a bit sensationalized, but the present evidence is fully consistent with a non-causal relationship as well.

gaius2• 16 years ago

Have you ever eaten a meal, and afterwards felt uncomfortably full? Or have you ever been interrupted halfway through a meal and when you came back, you didn't want to finish it?

It takes about 20 minutes for satiety to kick in - the feeling that is the opposite of hunger. The stomach takes this long to communicate with the brain. If you eat quickly, you spend longer in the window of time between when you have eaten enough and when the sensation of hunger diminishes. That's the key.

goodside4• 16 years ago

Right, that's why I say I think they're at least partially right. However, I can come up with a few other theories for why the opposite could be true as well.

Just off the top of my head: Whether the food you consume is burned immediately or stored as fat is regulated significantly by taste sensations, as evidenced by studies where people were forced to eat diets consistent of bland-tasting (but otherwise not especially healthy) food, and lost significant weight. Also, people who eat ad libitum will gain more weight than people who consume identical amounts of food through a gastro-nasal feeding tube. Studies on livestock have shown you can promote weight-gain by adding water to dry chow, which makes it taste better but obviously does not alter its nutritional content, even though the animals are fed the exact same quantity of chow. So, it's reasonable to at least suspect that doing something that increases the taste sensation of food, such as instructing people to chew longer before swallowing, might cause weight to increase.

I don't know which of these is true with certainty. The evidence is still somewhat ambiguous.

jerf• 16 years ago

Yes, but when I stuff myself on one meal, accidentally or otherwise, my next meal is smaller or sometimes even nonexistent. That won't a priori lead to obesity.

This does nothing to address the real question, does overeating cause obesity or does obesity cause overeating? I'd be much happier if the dietary research community would stop designing experiments that are intrinsically blind to that question and start actually examining it.

("Good Calories, Bad Calories" has already been brought up, but I would point out that if there is anything to take away from that book, it is not that he has proved the point that obesity causes overeating, rather than the other way around. The point he really proves is that it is a reasonable hypothesis that fits the facts, including the experiments that have been done, and it has not been adequately tested. It has been unscientifically discarded-by-axiom. If it is put to the test and fails, so be it. But this appears to be yet another experiment that fails to distinguish between the two cases at all, and therefore is not all that interesting to me. This, BTW, is not news to Taubes, it is all he really claims, too.)

fgf• 16 years ago

I eat calorie dense (but low carb) food quickly. I got really low body fat eating this way. I think this, at most, is a key.

rsheridan62• 16 years ago

Sure. I think it probably works due to my own experience, but slowly sipping milkshakes all day is not going to make you slender. Obesity has multiple causes.

sedachv• 16 years ago

I strongly suspect the key connection here is insulin response. Eating slowly is probably akin to eating foods that do not cause spikes in insulin levels. What leads me to believe this is that there has been a study (sorry, don't have the link) that changing the order in which you eat certain foods as part of one meal has a similar insulin dampening effect.

jacksoncarter2• 16 years ago

The key to obesity is simple:

  Calories In > Calories Burned = Weight Gain

If you consume calories that you do not burn, you store them for later use in fat. Is that simple answer incorrect or do people refuse to believe it because they don't want to increase output or consume less?

This is a subject of irrationality I have trouble understanding. The answer is there and known, but it isn't believed or accepted or something. Or do we accept it, but we just have a greater desire to avoid manual labor than change our habits.

goodside4• 16 years ago

"If you consume calories that you do not burn, you store them for later use in fat."

This is completely and utterly not true. There is significant caloric content in excrement, and countless factors that determine how much of the food you consume is absorbed or excreted. Many weight-loss drugs (e.g., orlistat) exert their effects by preventing absorption rather than consumption.

jacksoncarter2• 16 years ago

If I change the word "consume" in my comment to "absorb" then the point is the same. I'm not really one to care to argue about particular words used in the discussion, but more the point of the discussion.

If you consume fewer calories, you also absorb fewer calories. Is that not true?

Your comment only reinforces my point, which is that people would rather consume more, that is, pay for a doctor to prescribe a drug, pay for the drug, consume the drug on a regular basis, than simply consume less food or do more work. I'm sure orlistat has a huge list of side effects. It probably does stuff to your body they don't even know about. It would be better to consume less food or burn more calories than to consume a drug to enable the overweight person to consume more food than they need. And think of the moral implications of over-consumption. Doesn't it seem odd that we are selling people pills to enable them to consume more than they need? What about those who need more than they get?

Yet, people choose to consume the drug. The question is, Why? and you didn't even come close to answering that question, but rather focused on a semantic issue that doesn't move us any closer to understanding.

At one point, I too was overweight. I ate 3 big meals a day, I sat behind a computer all day. I never exercised. Then I started eating less and exercising and I lost weight and became healthier.

ars• 16 years ago

That is the key, but not the solution.

You have two problems:

Feedback loop: When you burn more calories the body requests more calories in. So simply increasing calories burned does not work.

And self-controlling calories in is pretty much impossible for most people who have access to food.

The solution is tricks. All sorts of tricks to trick a person into reducing calories in despite the bodies demands.

gaius2• 16 years ago

Because a thing is simple, doesn't mean it's easy.

rsheridan62• 16 years ago

Sure, it's simple. A newborn baby doubles it's weight in a month. Why? Because it's eating a lot. A woman gets pregnant and puts on 30 pounds? Why? Because she's eating a lot. A teenager goes through a growth spurt and puts on 20 pounds? Why? He's eating a lot. A cancer patient loses 20 pounds quickly. Why? He's not eating much.

But this might not be the most useful level of abstraction to look at. It's sort of like looking at this comment and thinking that it's on your screen because your computer fetched it from your wireless router.. true, but not very useful or informative. You might want to step back and ask why these people are eating so much or so little. Surely it isn't just willpower (whatever that is). There are plenty of slender people who can't bring themselves to do things like study for an exam.

karzeem• 16 years ago

Every HN thread on diet mentions Gary Taubes' book Good Calories, Bad Calories, so I'll be the first to do it here.

The book makes a strong case that the key you mention is in fact a fallacy. There is a correlation between calorie surplus and weight gain, but saying the first caused the second is like saying (to use an example from the book) that alcoholism is caused by drinking too much — tautological, and not useful in fixing the condition.

Taubes goes on to argue that because of an underlying metabolic condition (induced by a carb-heavy diet, as it turns out), your body decides to gain weight and so makes you eat more calories than you burn. So it's not that you gain weight because you eat too much, it's that you eat too much because you're gaining weight.

Edit: sorry to rsheridan6 for using the "true, and not useful" turn of phrase without having realized someone else beat me to it. Guess that means it's a good one here.

nova• 16 years ago

> This is a subject of irrationality I have trouble understanding

That's because you are utterly, terribly wrong, and like you millions of people, including doctors. And that's why so many people have trouble losing weight. You think you have THE TRUTH, your truth is not working, then blame the world.

Just two things:

1) The actual first law of thermodynamics is:

(Calories In) - (Calories Out) - (Calories Stored) = 0

Note in particular this is a constraint, i.e., the absence of causality assumptions.

2) You don't eat pure energy. After the first law there is the second: http://www.nutritionj.com/content/3/1/9

3) Please read Taubes.

micheljansen2• 16 years ago

Although this is a pretty old article, I think it's still pretty relevant.

Interestingly, a colleague of mine has graduated on the subject by designing an augmented dinner plate to help people adjust their speed of eating: http://www.lissakooijman.nl/changing%20eating%20patterns.htm

She's currently working with dieticians and people suffering from obesity to develop this into a product. I don't know all the details, but they certainly seem to benefit from changing their eating habits.

ck2• 16 years ago

Correlation does not imply causation, though there is probably some truth here.

jasonkester• 16 years ago

It never ceases to amaze me that otherwise smart people will sit down to a meal and eat until they are physically incapable of stuffing more food into themselves. Every single time. The concept of "meal" is synonymous with eating until full, rather than eating until no longer hungry.

Further amazement comes when these same people, now obese, don't immediately do something about it. If you had any other terminal condition, you would do anything in your power to fix it. If you're fat, you just ignore it and get on with life.

It all seems so simple, watching from the outside.

narrator• 16 years ago

The only thing that affects how much weight you gain or lose over a period of time is calorie consumption, your height, age and weight, and to a lesser extent, your activity level.

Here's everything you need to know: http://www.fourmilab.ch/hackdiet/www/hackdiet.html

Literally, that's it. Read the hacker diet and you won't need to listen to or read another thing about dieting for the rest of your life.

Evgeny• 16 years ago

Personal anecdote: I eat quite fast and I have no troubles keeping my weight at a stable 75kg at 178cm height. Secret? Well, I know generally how much I eat, so that's how much I put on my plate. When it's finished, it's finished, no matter if it took me 5 or 50 minutes to munch through stuff. And of course, if I sometimes give in and consume a lot of pizza, ice cream or similar - I will see my weight go upwards, even if I eat that pizza veeeery slow...

davidwparker• 16 years ago

Based on my personal experience in the military, I'd have to disagree with this. Perhaps obese people are just plain hungrier and that drives them to eat faster? But eating faster in itself does not lead to obesity.

Speed of eating 'key to obesity'

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