The myth that drinking Ice water or eating ice forces your body to burn calories to melt the ice and heat it up to 98.6 degrees is all over the web, (and was mentioned by Cecil in a 1997 post about beer), but doesn’t your body produce excess heat as a waste product of metabolism?
I’ll forgo the obvious calculations and Calorie/calorie confusion and just ask - Will eating ice cause you to lose weight, or just radiate less ‘waste’ body heat?
My sanity begs for a reply
No. It is a negligible expenditure of energy.
There was a series of threads, some quite acrimonious, on this topic a few years back. The most convincing point of view seemed to be:
Yes, your body produces lots of waste heat.
Yes, your body uses energy getting rid of it.
No, exercising in the cold or drinking ice water will not always burn more calories than exercising in normal temperatures or not drinking ice water. It may just cause you to have to sweat less.
At some point, like when you swim across the Arctic Ocean in January, it certainly does burn extra calories.
Nobody seems to have the faintest idea at what point it becomes beneficial
Here:
http://boards.straightdope.com/sdmb/showthread.php?t=57799&highlight="ice+water"+weight
http://boards.straightdope.com/sdmb/showthread.php?t=163582&highlight="ice+water"+weight
And Cecil’s input: Is it possible to diet with beer?
Short answer: about 3/4 of a gallon of ice water = 110 calories. Which is, conveniently, about as many calories as you’ll burn running a mile. Your choice.
Sorry, I read closer and realized that you already read the beer article.
Also, it takes energy to bring your body to its average core temperature from either direction, so I don’t think eating ice would just cause you to radiate less body heat. It would indeed burn calories, the question is simply how much.
My understanding is as follows.
Your body has to burn calories to heat the water. The question is whether these calories are extra calories that may have otherwise been stored as fat (making the ice diet valid) or if they are calories that would otherwise be lost as heat.
First off, being cold will actually lower your metabolic rate. . . but that’s not the main issue
As I see it, all food that is burned generates both usable (bio-chemical) energy and unusable heat (which is dissipated). Almost always the bio-chemical energy is the limiting factor, but when the body is unable to maintain its temperature (IE heat is the limiting factor) - we shiver which burns extra calories - wasting the bio-chemical energy in the form of muscle spasms, and utilizing the heat to raise internal body temperature.
This implies to me that unless you’re shivering, you will not lose fat by drinking cold water or eating ice.
This seems right to me, but so many sources seem to quote the ice diet as working that I’m not sure anymore.
More input would be appreciated.
I don’t understand how the second part follows from the first part. Since it takes energy to bring your body to its average temperature from either direction, doesn’t that means that drinking ice water (below a certain threshold where you start to shiver and actively generate heat) could in fact cause you to burn fewer calories, since the ice water would be doing the job of keeping you cool rather than forcing your body to expend the energy?
I don’t see the difference. Exactly what do you mean by “that would otherwise be lost as heat”? The important point is that the calories are being burnt, isn’t it?
After all, where are these calories coming from? If we’re drinking ice water, or some other frozen (or cold) zero-calorie (or low-calorie) food, then there is only two possible places when the body can get the energy to heat it with: (1) fat that has already been stored, or (2) food that is currently in the process of being digested and will become fat if we don’t burn it to heat up this ice water. – Either way, this is effective, isn’t it?
**Chorpler ** has it mostly right. Put simply:
1/ The body produces a lot of heat as a by product of living [which means that it might very well be able to heat the cold liquid without doing additional work, beyond that which it would have anyway].
2/ The body has multiple strategies for maintaining core temperature, only one of which is increasing metabolism or shivering (ie using additional calories)
3/ Those latter strategies only kick in when you are already quite cold [a situation which is not normal for most people most of the time]
The only points I would disagree with Chorpler on are:
I have never seen any cite for this that put the energy cost of getting rid of heat at above the completely and utterly trivial: so trivial that it is an effect that can be safely ignored for the purposes of this question. It just doesn’t take any significant calories to open valves leading to surface capillaries to allow warm blood to the extremities to radiate more heat, or to sweat. There is no significant work being done whatever.
Yes, they do. Read this very detailed paper on the subject. It’s all pretty well studied, by the look of it. There are pretty well established thresholds involving your core temperature, your shell temperature, and things you might then do (like drink cold liquids) and what will and what will not happen. I’m not going to go over it all again but basically you have to be moderately cold already before your body’s reaction to the ingestion of ice water is going to be to burn more calories just to warm up.
If you read the cite you will find that if you sit in a bath of 20C (68F) water up to your neck, then drink iced water you will induce shivering ie burning of additional calories. Above that shell temperature, the body does not significantly burn additional calories just to stay warm. 20C may not sound too cold, but don’t forget that 20C water is quite cool because it takes heat away so much faster than air. It is far below what is comfortable to sit still in for any length of time.
Do you have a cite for the proposition that it takes any significant amount of energy for your body to reduce core temp?
Do you have a cite for the proposition that eating ice would indeed cause your body to burn any significant number of calories under normal climactic conditions?
My experience in this debate (which as you will guess is long) is that these are canards repeated endlessly but never cited.
Cecil’s calculation is wrong. He doesn’t consider physiology or that humans are generally have waste heat on hand at all. I don’t know exactly how wrong he is, because I have never found a cite giving precisely the data required. But the only question is how wrong he is.
No it isn’t. Calories are always being burnt. You burn significant calories just being alive. A diet that gives you no advantage doesn’t qualify as a diet.
This is the point that trips up a lot of people (it did me when I first started thinking about it). The ice water gets warmed, that has to use up calories, so the ice water diet has to work, right? What is missing is a consideration of whether drinking the ice water uses up much more calories than would have been burned by your body over the same period of time anyway. If not, the diet ain’t a diet.
Think of the cold beer can on a car engine driving from A to B analogy. By the time you get to B, the beer would have been warmed. Conversion of fuel into heat sufficient to have warmed the beer must have been burned. But no more fuel will have been burned than if the beer can was in the trunk, right? So you’d hardly call putting a can of beer on the car engine a “diet” that increases fuel consumption.
To give the question some perspective, consider this. According to this site a 175 pound man burns 14k/cal per 10 minutes just sleeping, and 57 k/cal per 10 minutes when engaged in light activity. At only 40% efficiency (per this SDMB staff report) that is some 50 k/cal per hour of heat production just sleeping, and 205 k/cal of heat production per hour when gardening. That is sufficient (according to Cecil’s figures) to warm a 355ml beer can from freezing to body temp in 15 minutes sleeping or about just 4 minutes gardening without using one additional calorie beyond that which you would have burnt, just doing those activities.
Princhester, you are the man - thank you. I think what you’ve said is a more eloquent and cited version of what I was trying to say. I have been trying to inform a coworker who’s using the ice water diet, and they cited multiple sources on-line saying it worked. . . most of which were retarded blogs, or ‘diet’ columns written by morons. . . but then I saw that Cecil had kinda endorsed it!
Glad to know he was wrong.
The car hood analogy is great.
Again thank you.
Yes. Heat is heat, there isn’t any ‘extra’ that we somehow get rid of without the normal laws of thermodynamics applying. Metabolic energy will go to melting the ice and heating it up to 37°C. It just doesn’t take very many calories to do that in comparison to the number of calories in food, or in fat deposits.
No, but I have run many miles in the sweltering heat and can vouch for how much more exhausting it is than in cooler temperatures. I guess what I meant to say is that it takes energy to maintain body temperature, but I realize now that I’m talking out of my ass and I’ll let more educated folks take over.
Thanks for the corrections, Princhester. It’d been so long since I read the threds referenced that I forgot about the points you mentioned, particularly the vasoconstriction and 68-degree shell temperature thing.
After re-reading that thread and looking at swyves’s claim that the whole thing is pretty much accurate, I did a Google search for “non-shivering thermogensis” and came up with some interesting reading.
Brown Adipose Tissue (Wikipedia)
I wonder how much brown adipose tissue adults have.
Back in the late 80’s, the answer to that question was ‘none’. The answer doesn’t appear to have changed in the intervening years:
Of course the normal laws of thermodynamics apply, but that doesn’t have anything to do with the question. Your body does produce a lot of extra heat that it dissipates into the environment. The average person generates heat equivalent to a 100-watt light bulb, if I recall correctly, when you’re just standing there. The point under discussion is, will ingesting something cold cause your body to burn extra food to warm it up, or will it just warm up as a side effect of all the waste heat your body is pouring out anyway?
Fascinating. Thanks for that, Squink. So it appears that adults lack the type of tissue that specifically generates heat in infants.
There ain’t no such thing as ‘side effect’ heating.
People put out a hundred watts or so at rest, and if they want to maintain body temperature after eating something cold, they must temporarily put out 120 watts or whatever, to warm it up.
This common misunderstanding of heat flow is the same one which Una Persson addresses so nicely in this thread: Most Efficent Home Heating Strategy?
What? How about the analogy in the other thread about how running your car’s heater doesn’t take any extra gas, because it’s already producing way more heat than you need?
Your body produces a lot more heat than you need (assuming you are in a normal environment, not floating in a frozen lake or something) as a consequence of metabolic activity, and in order to maintain a constant body temperature, it has to shed a lot of that heat. If you cool some things down a bit, why would it suddenly start putting out more heat rather than just pour out less heat to the environment?
I can vaporize liquid nitrogen by breathing hot air onto it, but I’m not thinking that that somehow uses up extra calories. That heat was lost anyway.
I don’t see how it applies.
At first, this made a lot of sense to me. But then I tried to think of ways to challenge it, and came up with this:
A car engine does not require any particular temperature to operate properly. All it needs to do is consistently produce little explosions in the pistons. It does have a coolant system, but that is merely to prevent overheating, which does bad things to the oil and other fluids. Being too cold is bad also, but the car does run when it is cold, just not as efficiently. There’s no system to burn more fuel when the engine is below optimal temperature.
In sharp contrast, my understanding of the concept of “warm-blooded animals” is that if anything occurs which has the effect of lowering the body temperature, the body will work extra (i.e., burn more calories) to bring the temperature back to the proper level. This will occur not only when one drinks the ice water, but even when one carries a bottle of ice water in his pocket: The ice water in the pocket does cool down the skin in the immediate area, which does cool down the blood flowing through that skin. As that blood flows through the body, the body temperature is lowered, admittedly to a very small degree. In turn, an admittedly very small number of additional calories must get burned to bring the body temperature back to the proper level. The exact same effect will occur if one even puts his hand in the cold air of a refrigerator for a moment. or forces some sweat to evaporate by standing by a fan: Anything which causes the body temperature to go down, even by a tiny amount, will force the body to burn a correspondingly tiny number of calories to compensate. And if one introduces a large amount of a very cold substance to the body’s internal systems, those small numbers become appropriately large.
Where’s my error?