"A calorie is a calorie" violates the second law of thermodynamics

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC506782/

by krishna2 • 15 years ago

120 61 15 years ago

ncbi.nlm.nih.gov

thirsteh• 15 years ago

I thought that "Richard Feinman" was just a misspelling of Richard Feynman, then I noticed the dates. That would be just like him to author something like this though.

dmarquis• 15 years ago

Its a good first approximation so to a physicist it might as well be true.

daoudc• 15 years ago

Ouch. Yes, I clearly remembering being taught that Physics is approximation.

rbanffy• 15 years ago

This is not be the Richard Feynman you are looking for:

http://en.wikipedia.org/wiki/Richard_D._Feinman

apinstein• 15 years ago

tl;dr version:

Calories derived from fat vs protein vs carbohydrates have different inefficiencies in converting them from their theoretical caloric value to their useful work in the body.

Fat is the most efficient with a loss of just @ 2-3%, carbs are at 6-8%, protein 25-30%. [edit Most of] this loss is in the form of heat.

It was not mentioned why this excess heat would not simply be offset by the body avoiding the normal processes it takes to maintain body temperature. Presumably the body generates enough heat as a by-product at room temperature and thus there is nothing the body can back off of to make use of the waste heat described above.

somebear• 15 years ago

FTA:

> Some of the available energy is lost as heat and in the internal rearrangement of chemical compounds and other changes in entropy.

So not all of the difference in efficiency is made up in the form of heat. Unfortunately, I don't remember enough biochemistry nor thermodynamics to dive deeper into this, but I think this article is a good starting point for a discussions, which has otherwise just been dismissed with the "a calorie is a calorie" argument.

kenjackson• 15 years ago

Funny, I learned this in nutrition class about 20 years ago. It's something that clearly has been known for a long time, yet its never been popuar in the common discourse.

Udo2• 15 years ago

Exactly. I also believe it doesn't really matter, because the inefficiencies of converting sugars to body fat are pretty much irrelevant. Proteins may have a more significant inefficiency, but it's hard find food where they are the majority component.

When people overeat grossly, those 5% won't make much of a difference. On my binge days, I consume upwards of 5000 kcal and it doesn't really matter if it's actually just 4750 kcal - it's still too much.

So yeah, in practice, a calorie is pretty much a calorie.

chipsy• 15 years ago

Related: I've been adding a bit of white vinegar to meals as a way to lower the effective GI of carby foods. Seems to work pretty well.

ghshephard• 15 years ago

Results will, apparently, vary. Your metabolism may be blessed as vinegar reactive. Timothy Ferris used a glucose meter to try and track impact of Vinegar on the GI, and didn't get positive results:

http://bodezfitness.com/blog/tasso/post.cfm/post/4841/2-pre-...

Evgeny• 15 years ago

Is it possible that the taste of vinegar caused you to subconsciously eat a bit less?

run4yourlives2• 15 years ago

"A calorie is a calorie" is good enough, however.

People aren't fat because they are consuming 2500 calories from a Big Mac and Fries rather than 2500 calories from carrots. People are fat because they are consuming 6000 calories and burning off 1300.

The message is simplistic, sure. For a large majority of overweight people though that's all that is required. Somewhere between reducing caloric intake and becoming fit, the message that not all calories are created equal sinks in, if for no other reason that it quickly becomes apparent that you'll starve only eating one meal of McDonald's a day.

cjp• 15 years ago

Negative. You miss the entire point of the article.

Why are people consuming 6000 calories? They are always hungry and eat too much food.

Why are they always hungry? They eat and drink too many carbohydrates. Too many carbohydrates leads to high blood sugar which leads to too much insulin. After the insulin does its job, the blood sugar crashes causing hunger. The cycle repeats, causing problems including insulin resistance, excess fat storage and type 2 diabetes.

What is the solution? Don't consume carbohydrates and avoid the hunger/sugar/insulin cycle.

Groxx3• 15 years ago

Erm... did you read the article?

The only mention of carbohydrate's effect is because it's chosen as a large, easy number to reduce in favor of raising the protein amount, raising the overall inefficiency of the system. They listed, in Atkins-like diets, that shifting from 55% carbs to 8% carbs (with the change going to increased protein intake) results in about 140kcals less useful energy.

That's it. From where in the article are you drawing insulin/diabetes/hunger connections?

ak4life• 15 years ago

Don't consume carbs? This sounds insane. What about a balanced diet of caloric value inline with one's caloric output?

noarchy• 15 years ago

I expect that you'll end up getting downvoted by the "carbs are evil" crowd, but I think you're largely correct. Too many people are looking for the magic bullet that will let them remain sedentary, overeat, and yet still lose weight.

Groxx3• 15 years ago

Nice to meet you, Nostradamus v2.0 :)

ugh4• 15 years ago

Simply counting calories will reduce your weight. I can pretty much confirm that now. Over the last eight months I tried to stay below 1900 calories per day and I have lost 17 kilo. As much as I wanted to, I did not manage to change my diet in any meaningful way, I’m just eating less. I didn’t even manage to keep up a regular sports routine. But my fallback – mercilessly tracking my weight and counting calories – saved me. (I would very much want to eat better. Many of the things I’m eating now have so high calorie densities that I can only eat very little of them.)

I do know that I will have to track my weight and count calories for the rest of my life. That’s ok. (As a teenager I already lost a substantial amount of weight with the same method but I gained it all and more back because I stupidly stopped tracking my weight and counting calories. I’m confident that I won’t make the same mistake again.)

keeptrying2• 15 years ago

If you simply cut out carbs you will lose a ton of fat.

But yeah if you want to eat carbs and be healthy you have to basically count calories for the rest of your life.

mannicken2• 15 years ago

I agree with that. I lost around 10kg in a couple of months on a steady diet of ice-cream and chicken, counting calories as I happily ate my ice-cream.

regularfry• 15 years ago

Surely this is just an application of the maxim "Anything measured improves," rather than anything specific to weight control?

lionhearted• 15 years ago

Experiment with healthy foods you can pre-cook. Rice cooker with rice and beans takes 5 minutes to put on and feeds you all day. Leave it soaking in water overnight and it's 5 minutes of cleaning in the morning.

Can hard boil eggs with minimal attention (set the alarm on your cellphone), can make 6 or 12 at a time and those will last you a couple days.

Get some vegetables that require minimal preparation - I used pickled vegetables and like them, but canned would be fine too. Maybe tuna or sardines, try them all and see what you like.

Then you've got rice+beans, and you add on some vegetables to it, and then either hard boiled eggs, tuna, or sardines - fast, cheap, healthy.

colomon3• 15 years ago

Errr.... consuming 6000 calories and burning off only 1300 would cause you to gain more than a pound. That might be a daily intake for someone weighing 600 pounds, but it's hardly the situation for your run-of-the-mill fat person.

Putting it in practical, personal terms -- I was laid up for six weeks for medical reasons this winter, and my bad habits continued for the next six weeks as well. Over that period I gained about 18 pounds, one of the worst periods of weight gain in my life. Simple math (and ignoring the data presented in the article!) tells you I must have been eating about 5250 excess calories a week. Roughly speaking I was probably eating 23,000 calories a week when I should have been having 18,000.

Now suppose I had gained that weight on a low-fat diet. The study cited in the article suggests that if I had been on a low-carb diet instead, I wouldn't have gained any weight at all! That's a pretty significant result. (Of course, in practice I was on a "whatever" diet.)

For those of us living on the edge, trying to shave off 500 calories a day, the knowledge that not all calories are created equal is a Big Deal.

run4yourlives2• 15 years ago

It was an exaggeration to make the point. Sorry, thought that was obvious.

For your example: If you had eaten a low-carb diet, you'd probably need to have eaten 50% more food in terms of quantity in order to meet the caloric intake you were getting on the "whatever" diet.

That's my point. If you simply focused on the caloric intake and kept it at 18,000 a week (which seems high for someone lying in bed, to be honest) and still ate whatever you wanted, you would't have put on 18 pounds.

cschneid• 15 years ago

The other big thing that people end up missing is that most of your weight isn't from the food you eat. That's just where the energy came from. Your weight is oxygen / carbon / water / etc.

Also note: a giant tree doesn't dig out a giant hole where it grows in the ground. The dirt isn't the bulk of the tree's wood.

bruce511• 15 years ago

I'm not sure I follow you here. Aside from a medical condition you're not gonna accumulate water. And I'm not sure " breath less" would be a popular or effective diet technique. Yes, your body needs water and oxygen as part of using food, and turning into muscle or fat, but it's the food that does all the damage. A very brief evidence of this fact are those that exercise all the time (hence have both elevated breathing and water intake, and yet don't gain weight.)

Regarding the tree, you're absolutely right. If only you were a tree that would be a useful comment. Unfortunatly the metabolic process of a tree (all plants) is different to that of an animal. A plant requires water, carbon dioxide and sunlight. Throght the process of photo-synthesis (which only plants can do) carbon is removed from the atmosphere using sunlight as the primary fuel. So, if you like a plant "breaths" sunlight, "eats" air and defecates oxygen.

acon• 15 years ago

The fact that a tree builds itself out of thin air is one of my favorite tidbits of knowledge. However, this kind of metabolism is only used by plants. Humans, as all animals, gets their building blocks from what they eat and drink. All the oxygen we use from the air we breathe is exhaled as carbon dioxide.

Geee2• 15 years ago

This is actually pretty interesting point of view. In essence, you should try to breath out all the carbon you ingest. Measuring the carbon dioxide output would be a pretty accurate measure of the actual energy consumption in the body.

auganov• 15 years ago

I cannot comment much on thermodynamics/biochemistry as I don't know a bit about those, but unfortunetaly it seems like this study has ommited the fact that a high protein diet will always be more efficient in the beginning. They should NOT have taken weightloss that occured in the first week or two (to be on the safe side) into account.

Why? Protein-rich food tends to weight less, doesn't cause as much bloat. Actually a very high fat diet might cause most loss in the beginning. For example I eat a very high-carb diet,a lot of raw food that is not too calorie dense, it bloats you a lot providing few calories at the same time. If one day I decide to eat only ice cream (keeping ammount of calories the same) then on the next day there will be a sudden big loss. Of course it will be gone once back to eating what I eat before.

So when measuring efficienct of a diet you should exclude anything that happens in the beginning because it's always very very volatile in that stage. Especially when subjects tested ate a very different diet beforehand. You could also go on to talk about sodium intake which affects water retention which translates to changes in weight. That will cause a lot of fluctuation in weight in the beginning too.

I keep a very detailed log of what I eat and my weight with CRON-o-Meter. When I eat and drink same food for an extended period of time (and stay home all the time) my weight loss is almost calorie-perfect, meaning that you could convert the daily calorie deficit to grams and this is how much I would loose on each day. Only once every 4-5 days there would be a slight "bump", but if you look at the 7-day moving average it's virtually a straight line.

I went on vacations once and decided to binge, big time, 6000 calories a day (really!), at the end of the day it was very unplesant, but well the food was worth it, haha. Keep in mind that I weight 110lbs and eat around 1700 on a normal day. The weight of my body has increased probably by around 5-6 kg, 4kg was expected, rest was water retention etc. So the first few days back on a diet were crazy. One the first day a loss of 1.3kg (and that is after a 2 day fast already!). Next day 0.3kg, then 0.2 kg, 0.15kg, one day of no change and then a sudden increase of 0.6 kg, after that it gruadually stareted to approach the expected rate of loss (0.1kg/day).

Many people, when they begin a diet are very much like me going off a binge. Not as dramatic of course, but similiar. In a choice of different food can yield a big loss that won't be there long term. A lot of fad diets exploit that fact and so do high protein diets. People often go on those diets, loose even up to 5-10lbs purely because of eating a food that digests and affects water retention in a different way and maybe some other factors that I don't know of (10 would be a lot, but I guess plausible for a very fat individual). Some get satisfied with that small loss, go back to the old diet and then we hear about the mysterious "yo-yo effect", but in fact nothing strange has happened. Those that last and continiue the diet will often say that the "starvation mode" has kicked in. No, "starvation mode", the "water retention effect" is gone (simplification). Some, after hitting the "starvation mode" will even swtich to more calorie dense food increasing their total intake of calories but reducing the sheer volume of food and claim to have beaten the "starvation mode" with more calories. I even consciously use those tricks to manipulate my weight sometimes (as there it can affect my mood :-) ).

I guess you understand by now. Unfortunately most studies fail to account for that, so whenever I see a study that tries to prove something with a small sample size, conducted over a short time frame I'm very very skeptical. But then again, once your sample size and time frame get bigger controlling those people gets hard, too hard. You have to make sure they eat the exact ammounts of food they are supposed to eat. They sometimes give people directions like eat one cup of this, 2 cups of that, CRAZY! You have to portion the food for them, unless you explain what a "cup" of any given food is and make sure they PERFECTLY understand you will have huge errors even with 100% honest people. Accounting for bias is very tricky with those studies too, not going to work too good. Psychological effects actually get stronger and harder to control the longer the time frame is, so large N and a long time frame doesn't solve the problem either. Physical activity is another thing. Some people burn 200 without noticing. There's very few people that truly have naturally "fast metabolism", yet a big proportion of people that are thin claim to have that. "I eat whatever I want and stay lean", yea you do eat whatever you want but you don't want to eat much. Or they do sports. Or fidget all the time (which some claim could even burn off 500 in extreme cases).

Do a study with each group having at least 30 people, same gender, similiar weight, similiar height, healthy, close to no physical activity, not a fidgeter. Portion food for them, don't let them do it themselves. Measure everything they put in their mouth, water and multivitamin included. Weight each day at the same time, same clothes, make sure they pee beforehand. Do that for 3 months. Discard first 2 weeks of results. Perhaps the last 2 weeks too (people are more likely to cheat at the end). That's a study that I might care about, of course probably forgot about 20 other things I'd do.

I think conducting such a study would only be possible if you gathered a large group of dieting/nutrition enthusiasts like me. Too hard otherwise. I really sometimes wonder how they find people for those larger studies.

Getting my mom to diet was/is a BIG pain even given the fact that she was willing to drop some weight. She was also extremely biased in a lot of things she said even given that she probably knows more about nutrition then the average person as I give her a lot of lectures :-). Now try that with 100 "normal" people that you probably DO NOT control on a daily basis. I know for a fact that unless you drug those people, they are BIG enthusiasts or lock in a cage and monitor the bias will be enormous.

I could go on talking for a very long time. The conclusion is pretty simple. Most studies about weight loss are simply useless. There are many smart people in the field of nutrition I'm sure, unfortunatelly it's very very hard to find these amongst legions of incompetent people. I mostly see 2 kinds of the incompetent. One group is those that are simply stupid/lazy/don't care. They do a study to seem smart, probably because they need it to get some kind of a credential. They study something that 100 people already did, change two things, come up with a conclusion that is not too controversial so there's not too many people questioning (when you're findings are interesting everybody is going to point out even a slight flaw in the study, if you say what people want to hear you might get away with a large, fundamental flaw, because you state "the obivious" anyways). Another group of incompetent people are something I'd call the "ideology-driven", those are scientists that will do anything to prove their thesis. Actually I think those are a little better than the first group of the incompetent. You see, the stupid/lazy ones, they have almost a zero chance of comming up with anything interesting. The ideology driven ones can actually find something interesting.

Ok, well I'm tired writing that long rant on the field of nutrition (but I guess it applies to so many more fields of science). If you was bored enough to read the whole thing please also keep in mind that I admittedly have no education in that field, or any whatsoever, so everything I wrote is basically based on my personal experience and what I read on the Internet. But I do not think I have said anything that is far from the truth.

So as to that particular study, their reasoning might be right, but I wouldn't use that data to substantiate it. They are honest people though as they do explicitly say "one can't predict that the ratios will stay the same over a long term dietbut the calculations show that the possibility of metabolic advantage should not come as a surprise." And I'm afraid that the advantage would wear off. Also note that I'm not saying that I know from my experience that it does, because I have never really went long term on diet that's not high carb, I hate low-carb stuff. I only have tons of experience with short term effects and what I see in most studies are those short term effects that I know a lot about.

jvdongen• 15 years ago

The car/fuel analogy is a bad one. High-test fuel only makes sense if the engine in which you intend to burn it is designed to actually make use of its qualities to reach higher efficiencies (e.g. a higher compression ratio). If not, you're just burning more expensive fuel at the same efficiency.

That said, what really interests me is the mechanisms behind addictions. Why do smokers smoke, knowing full well by now that it will kill them earlier than non-smokers? Why stuff obese people themselves, knowing full well that it will cause serious health issues down the line.

Bottom-line I tend to agree with those who hold that 'a calorie is a calorie' and simply cutting down on food intake is a good enough principle, though perhaps not entirely scientifically correct, for the majority of obese people.

But why don't they do it? What makes it so attractive that they simply ignore the serious long-term disadvantages - and even in some cases deny the existence of said disadvantages even though in reality they must know they are real.

janjan• 15 years ago

> That said, what really interests me is the mechanisms behind addictions. Why do smokers smoke, knowing full well by now that it will kill them earlier than non-smokers? Why stuff obese people themselves, knowing full well that it will cause serious health issues down the line.

Let's take this one step further: Is the reason/mechanism a smoker smokes the same why I browse reddit and HN all day instead of working on my PhD?

eru2• 15 years ago

Probably not completely the same. There's a variable reward schedule behind browsing HN (and that can be addictive). Smoking seems to give a different `reward'.

stcredzero• 15 years ago

Here is an example that one of the best "rocks to look under" (as in pg's "What You Can't Say" essay) is the misapplication of fundamental laws:

http://news.ycombinator.com/item?id=2254906

The researchers who wrote this paper looked under that rock. (In this case, pop-science application of fundamental physical law. It's hard to get more fundamental than thermodynamics.)

(An example for you entrepreneurs out there, I'd suggest looking under Kerchoff's Law. Yes, it's a great principle to keep in mind when designing security tools like ciphers and cryptographic protocols. However, I contend it's applied in a counter-productive way when people think about real-world systems -- those have boundaries that are way too complicated for the application of Kerchoff's Law. Often, this is just an opportunity for someone to show they understand crypto theory, then throw up their arms and declare nothing can be done. However, the truth is that security often works or doesn't work because of the economics!)

raleec• 15 years ago

Also refuted here: http://news.ycombinator.com/item?id=1006980

hackermom2• 15 years ago

This is entirely besides the point of the study and the article, but why are the Americans the only ones who, in terms of human energy intake/consumption, say calorie when it should be kilocalorie? Why do they insist on being one thousand times off? "It's easier"? From where does this come from, and why does the rest of the world insist on being accurate?

woobar2• 15 years ago

Americans use term 'Calorie', not 'calorie'. 1 Cal = 1000 cal

http://en.wikipedia.org/wiki/Calorie

hackermom2• 15 years ago

...and the case-sensitive nature of this confusion is exactly the point I'm trying to get across - people just don't know the difference. A Calorie is a calorie! Just read the nutritional declaration on a few American food products and you'll find an equal amount of both. MB, Mb or mb, anyone?

terio2• 15 years ago

I don't think the difference in conversion efficiency between carbs and fat is relevant in a "normal" diet. The main difference is in how they are metabolized, and the effect they produce in the body.

I can only recommend everybody to stop loading huge amounts of carbs, specially sugar. Go for simple unprocessed foods, like fruits, vegetables, meat, fish, and so on.

The paleo lifestyle works just fine for me. I know it is hard to convince other people to do it. Even when they see me eat like I do, and they have seen the change in other people that adopted that practice, most people simply resist the idea. Check out http://www.scientificamerican.com/blog/post.cfm?id=mummy-say...

zecg• 15 years ago

I have found the perfect diet (or, rather "weight control algorithm"), have lost about 60 pounds and haven't gained them back for a couple of years now. The algorithm is extremely simple: "If you ate yesterday, don't eat today." It means I fast AT LEAST half days in a year (see: alternate day fasting). On fasting days, I drink water and green tea (with no sugar, of course). It has numerous purported health benefits. I can vouch for weight loss, lower blood pressure, more energy (perhaps paradoxically) and better digestion. It also frees a lot of time, since you don't have to plan, eat, or acquire food half the time and it turns out digestion also "needs" sleep, so I can get by with sleeping less on days I'm empty. The only side effect is that of lower blood pressure - I sometimes get dizzy if rising up fast from crouching. I started doing this after fasting for 60 hours every fortnight for a year, I loved the feeling and wanted more of it. It also makes me appreciate food much more on the days I do eat. As disclaimer (YMMV), I tend to avoid food additives which are known to be bad (coal tar-based paintstuffs, artificial sweeteners, certain emulgators and such) - the lists of those are widely available. And I try to eat whole-grain cereal products. I also keep kombucha as pets (very clean and quite pets, fermented tea is best poo ever) and I bake my own bread with wild yeast that has apparently managed to have aerial sex with my kombucha scoby.

shin_lao• 15 years ago

Careful with that kind of advice and things like "I have found the perfect diet".

It's much safer and simpler to lose weight and improve overall health by simply not eating crap (which is quite hard to do in a typical western country, I agree) and having regular exercise.

"A calorie is a calorie" violates the second law of thermodynamics

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