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Can I gain more than a pound as a result of eating a pound?
February 23, 2010 2:01 PM   Subscribe

Is it possible to gain more than a pound of body weight as a result of eating a pound of food?

Help settle a disagreement between me and my sister. She is really into fitness and diet and she insists that a person can gain more than a pound as a result of eating a pound of food. I don't think I can do her argument justice, but basically she says that it is all about calories, not the weight of the food. She says that if she ate a pound of cheesecake, she would gain more than a pound of body weight as a result.

I don't know anything about diet. But my argument is that the laws of physics make this impossible. Specifically the law of conservation of matter suggests to me that while I might gain less than a pound from ingesting a pound of something (e.g., a pound of water will all eventually be excreted in some way resulting in me gaining nothing), I can never gain more than a pound because my body can't create matter or mass out of thin air. To me it seems almost self-evident that if I ate a pound of cheesecake and somehow retained every molecule of it in my body I would gain exactly one pound.

Side note: I understand and concede that eating some things might cause me to retain water or something like that, resulting in extra weight gain. But that weight gain is a result of the water + the food, not the food alone. I still can't see how I can gain more than the weight of the stuff that I put in my mouth.

Who's right?
posted by crapples to Health & Fitness (44 answers total) 4 users marked this as a favorite
 
1 pound body weight = 3,500 calories.

The average American burns 2,500 calories in a day. Average. I don't know who this person is, but someone does apparently.

Therefore, for every 3,500 calories consumed intake without 3,500 output, you gain 1 pound of weight.

A calorie-dense food like cheesecake will cause you to gain weight faster than a calorie-poor food like celery.

This is not the same as asking whether a pound of bricks weighs more than a pound of feathers.
posted by jefficator at 2:06 PM on February 23, 2010 [2 favorites]


Even if consumed calories were entirely converted into fat (which they're obviously not - lots and lots of calories are burned and converted to other things):

1 oz of commerically-prepared cheesecake is 91 calories. There are 16 ounces in a pound, so 1 lb of cheesecake is 1456 Calories.

1 lb of fat stores about 3500 Calories. So no, eating 1 lb of cheesecake in excess of the calories you burn in a day will not equal 1 lb of fat.

Are there any foods with more than 215 Calories per ounce? That's a lot of Calories! It looks like milk chocolate is close, at 220 Calories per 1.5 oz.
posted by muddgirl at 2:09 PM on February 23, 2010


She means water retention.
posted by GuyZero at 2:10 PM on February 23, 2010


A quick calculation shows that vegetable shortening (Crisco) contains almost 4160 Calories per pound (@ 110 Calories/gram). It takes about 3500 Calories to generate a pound of body fat, so yeah Crisco should do it. This all depends on how efficiently your body processes fat, it varies between people. 3500 Calories/lb is a general average.
posted by Science! at 2:10 PM on February 23, 2010


This was asked before, and you're correct.
posted by ludwig_van at 2:10 PM on February 23, 2010


Your sister is right. You don't gain a pound by eating a pound of food. Some of what you eat is absorbed into your system and converted into energy (and then fat), and the rest your body expels. If an entire cheesecake is 7,000 calories, and you ate that, and did no exercise, you could gain more than a pound, theoretically.

All of this is sort of fuzzy math. Your body is constantly spending energy, and converting whatever you put into it to more energy. Still, you can basically figure out a general rate at which your body burns energy and needs to replenish it.
posted by pazazygeek at 2:12 PM on February 23, 2010


Is this immediately after consuming said food, or after the food has been digested?
posted by caveat at 2:12 PM on February 23, 2010


According to USDA, a pound of cheesecake has 1460 calories. If your body stored every last calorie as fat that still only gets you up to 1/2 of a pound.

Even a pound of butter has about 3200 calories, which is still short of the 3500 calories that make a pound of fat. In that light I think you will have a really hard time finding one pound of any food that will cause you to gain more than one pound.
posted by massysett at 2:13 PM on February 23, 2010


I'd say that you're right, but this seems almost impossible to test experimentally.
posted by electroboy at 2:13 PM on February 23, 2010


You are right, as is your logic. But, let's explore using her logic to see why she's wrong.

Her logic is probably based on an estimate like 3500 extra (kilo)calories = 1 lb. gained. That's really not a bad first-order approximation. She's also probably using a number like 9 (kilo)calories/gram of fat, which is a good approximation. This gives you ~390 grams (or 0.85 lbs) of pure fat to gain a pound of weight.

The problems with this logic are:
(1) Both of these numbers are approximations, and not perfect ones. You would likely find more precise numbers would give that the calories in 1 lb of fat are about right for a weight gain of 1 lb if (2) and (3) below weren't true
(2) The body is not perfectly efficient (or even close) at converting calories to fat,
(3) Most foods aren't pure fat with no other mass.
posted by JMOZ at 2:14 PM on February 23, 2010 [1 favorite]


Your sister is right. You don't gain a pound by eating a pound of food.

Right, you probably gain less than a pound. But not more.

If an entire cheesecake is 7,000 calories, and you ate that, and did no exercise, you could gain more than a pound, theoretically.

And that 7,000 calorie cheesecake would have weighed more than a pound.
posted by ludwig_van at 2:14 PM on February 23, 2010


Fat has 9 calories per gram. Alcohol has 7, Protein and carbs 4 each. There are 454 grams per pound. Therefore a pound of fat has 4086 calories, alcohol 3178, and carbs/protein 1816.

So, it looks like a pound of fat could actually be 1.16 pounds. How the physics work though is beyond me. But it's not simply calories in - calories out = weight gain. But how exactly it works has been then subject of many an argument through the ages.
posted by cgg at 2:15 PM on February 23, 2010


GuyZero has something there -- if the weight gain can happen temporarily, then a lot of salt in the pound of food will temporarily increase water retention until the salt is eliminated from the body. You can easily add multiple pounds of water for a while this way, but it wouldn't be permanent.
posted by buzzv at 2:17 PM on February 23, 2010 [1 favorite]


This whole argument played out in the thread I linked to above. If a person takes in water, that water has mass, too. A pound of food plus a pound of water equals 2 pounds, not 1 pound.
posted by ludwig_van at 2:19 PM on February 23, 2010


Assume you've already eaten the exactly perfect amount of food to balance your day's calorie loss.

Assume there is a food such that one pound of it will deliver more than 3500 calories to your body. I've no idea whether this is true or not, and it would also depend on how your body deals with it. I have no trouble believing that a pound of some oils will have more than 3500 calories, but if you eat a pound of oil, most of it is just going to spew from your bum muy pronto. Not turn into more you.

If you eat that food, you could gain more than a pound of weight.

Some of that weight would come from the food itself.

Some of that weight would come from the air you breathe.

Some of that weight would come from the water you drink.

But when you put together that food and the air and water, and probably trace elements blah blah, your body is going to build more than a pound of you because you ate that pound of food. It won't just be retained water, it will be your flesh. And it would be silly to assert that the food didn't do it, only the food + water + air did, because the water and air are necessary preconditions for being alive. It's like asserting that the food didn't cause the weight gain, only the food plus your cells did.

You might well be right because there is no actual food product that can actually deliver the appropriate load to your body.

But your logic isn't right, for the simple reason that your body takes in more than food.
posted by ROU_Xenophobe at 2:22 PM on February 23, 2010 [6 favorites]


Conservation of matter says you can't gain more weight than you take in. But that's not the same as saying you can't gain more weight than you eat, because you also take in mass by drinking and by breathing. Some of the food, water and oxygen mass you take in is incorporated into fat cells; some is excreted. The difference is the weight you gain.
posted by Bardolph at 2:25 PM on February 23, 2010


ROU_Xenophobe has it. If you eat 3,500 calories and your body decides to store them, it now has the energy it needs to build a pound of fat out of stuff you've eaten, drunk, and breathed.

Here is where you are intuition is right: that stuff itself must have a mass of more than a pound, but that's not difficult: we eat, drink, breathe, and excrete a lot of matter every day. It's not the food which provided the 3,500 calories that needs to provide all the mass.
posted by wyzewoman at 2:27 PM on February 23, 2010 [1 favorite]


According to some googling, there's 1849 calories per 205g of lard, and 205g of lard is 0.45 pounds.

So theoretically if you ate a pound of pure lard, you'd consume 4091 calories.

The question of whether your body could actually process all those calories I'm leaving to a stronger man than me.
posted by cali59 at 2:36 PM on February 23, 2010


There's an easy way to visualize this.

Place one pound of flammable stuff into a fireproof box, and weigh the box. It doesn't matter what stuff the stuff is made out of, the box will be one pound heavier than it started.

This is you eating a pound of food.

Now, put one pound of stuff in the box and set it on fire. When it stops burning, weigh the box. It will be heavier than when you started, but it will not be more than one pound heavier.

This is you eating a pound of food and then digesting it for energy.

Thus endeth the physics lesson.
posted by Cool Papa Bell at 2:40 PM on February 23, 2010 [4 favorites]


If the OP's sister is including water then they're basically arguing the same point.

Personally I don't think the sister is including water in her argument - the OP says that you can gain more than 1lb as a result of eating 1lb of food. To me that says the additional lb can only come from the 1lb of food - obviously realistically we also need to drink, but realistically we wouldn't be eating 1lb of cheesecake either.

I'm intrigued by the contradiction of 3500 calories to burn/gain 1lb of fat vs 9 calories per gram. The only thing I can think of is that creating or burning fat requires extra calories but 500 extra seems a lot.

Also, ROU_Xenophone... please remember to exhale ;)
posted by missmagenta at 2:42 PM on February 23, 2010


This is you eating a pound of food and then digesting it for energy.

Oh, and keep in mind that it takes energy to turn matter into energy. You spend calories digesting food. In other words, to properly model this in the above demonstration, shave a few ounces off the side of the box when you set it on fire.
posted by Cool Papa Bell at 2:42 PM on February 23, 2010


How is it possible that you can accept that a pound of food does not equal a pound of body weight when it comes to low-calorie foods, but that you can't beleive the inverse for high calorie foods?
posted by Kololo at 2:50 PM on February 23, 2010


How is it possible that you can accept that a pound of food does not equal a pound of body weight when it comes to low-calorie foods, but that you can't beleive the inverse for high calorie foods?

Because there's a limit to how calorie dense a food can be. Fat is the most calorie dense macro-nutrient. If you eat 1lb of fat do you expect to gain more than 1lb of fat, if so, where do think its coming from?
posted by missmagenta at 2:59 PM on February 23, 2010


I don't think I can do her argument justice, but basically she says that it is all about calories, not the weight of the food.

On this point, she's right, it is all about calories not the weight of the food and theoretically if there was a food that had for example 6000 calories per lb, then yes you would gain more than 1lb

She says that if she ate a pound of cheesecake, she would gain more than a pound of body weight as a result.

This is where she's wrong. 1lb of cheesecake does not have enough calories to convert into 1lb of fat. Nothing we would call food (as opposed to an ingredient like the crisco example - and even then I'm not convinced even with the calorie discrepancy but I have no evidence on that) has enough calories per lb to cause you to gain more than 1lb
posted by missmagenta at 3:11 PM on February 23, 2010


Presumably you could eat less than a pound of salt and end up retaining a full pound of water which, being water, isn't food.

The sister is wrong, but can be right if you finesse the definition of "food" enough.
posted by GuyZero at 3:21 PM on February 23, 2010


I'm intrigued by the contradiction of 3500 calories to burn/gain 1lb of fat vs 9 calories per gram.

The difference is that 1lb of body fat actually contains some water and other stuff - it isn't pure fat. So if you eat 1lb of pure fat, you get about 4100 calories, while you only store about 3500 calories in a pound of body fat. The difference comes mostly from stored water.

So the question is if the human body is 85% efficient at converting energy consumed as pure fat into body fat or not. Does anyone know?
posted by ssg at 3:22 PM on February 23, 2010


Surely not — breathing aside, there cannot be a way that putting 1 lb of matter in your body is going to directly cause it to add more than 1 lb of weight to its total! Where does that extra matter come from? Or put another way: if you eat and drink five pounds total every day, no more and no less, you could not possibly gain more than 35 lbs in a week. It's just not feasible, whether you're eating celery or lard!
posted by TochterAusElysium at 3:22 PM on February 23, 2010


Thanks. Too much to respond to, but a couple of clarifications are in order:

- The cheesecake is just an example. The real question is whether or not you could eat a pound of ANY food and gain more than a pound as a result. Many of you have already picked up on this.

- I appreciate the comments that have suggested that some foods will cause us to retain more of other kinds of mass via breathing and drinking. But I think the essence of the question is whether or not the pound of food, controlling for all other things, could result in more than pound of body weight. If I'm reading the responses correctly, this could never happen in the real world, but some of you seem to think it's theoretically possible (if, for example, a pound of something had 6000 calories). I still have my doubts.

- Sorry, I really did search for previous questions and I didn't catch that this had been asked before. Thanks, ludwig_van.
posted by crapples at 3:25 PM on February 23, 2010


but some of you seem to think it's theoretically possible (if, for example, a pound of something had 6000 calories). I still have my doubts.

Bear in mind that the 6000 calories per lb example is a hypothetical alien substance that defies the laws of physics as we know them
posted by missmagenta at 3:42 PM on February 23, 2010 [1 favorite]


To see how this would be possible, the relevant scientific field is chemistry, not physics.

Food eaten undergoes a bunch of chemical reactions, some of which can add hydrogen, or oxygen, or nitrogen from water drunk and air breathed.

Addressing the question of whether someone can eat a pound of food and gain more than a pound of body weight, excluding fluctuations in hydration: As usual, the devil is in the details.

Unfortunately, we don't know all the details. And many of the details we do know are contentious and/or hard to measure. My guess? I think that theoretically, it's possible. As a practical matter, I think it very, very unlikely.

Oh, and: Provided you breathe through your mouth, you are correct that you can't gain more weight than the weight of the stuff you put in your mouth, and with that caveat, you are correct in invoking physics as the applicable science field.

Hmm... I suppose I should add that the reason people are using calories in constructing their arguments is because calories are much easier to measure than molecules.
posted by Tuesday After Lunch at 4:03 PM on February 23, 2010 [1 favorite]


I appreciate the comments that have suggested that some foods will cause us to retain more of other kinds of mass via breathing and drinking. But I think the essence of the question is whether or not the pound of food, controlling for all other things, could result in more than pound of body weight.

I think you're misunderstanding the point I was trying to make.

Let's divide the weight of your body -- everything within your skin -- into You and Not You, and we can go ahead and put retained water in the Not You. You is your flesh and bone.

When you eat stuff, it gets broken down. Some of it stays Not You and turns into poop. Some of it turns into energy and (IIRC) mostly gets exhaled as CO2. Other bits of it get rearranged into more You.

My point is not that Arcturian Death Cheesecake will cause you to retain more "other kinds of mass," which I have to think fits into some sort of Not You category. My point is that the pound of cheesecake can allow your body to build more than a pound of You, because your body is already going to be eating other things and breathing and drinking and shitting and pissing in some normal amounts whether you eat the cheesecake or not (offer not valid for the undead). Change only eating the cheesecake, and if it's calorically dense enough you could end up with more than a pound of new You, real genuine You, built from some of that cheesecake and some other things you were going to have passing through your body anyway.

But it isn't that calorically dense, and probably nothing is.
posted by ROU_Xenophobe at 4:22 PM on February 23, 2010


So the question is if the human body is 85% efficient at converting energy consumed as pure fat into body fat or not. Does anyone know?

It differs greatly depending on the type of food, such that you can't really answer this question. For instance, there are some types of fats that are completely indigestible.
posted by Cool Papa Bell at 4:56 PM on February 23, 2010


When water retention is involved, this is sort of possible (but of course the water weight has to be consumed as well). For example, a common supplement for those interested in building muscle is Creatine. Creatine is an amino acid that provides energy for muscle contractions (in low endurance, high energy cases). Supplementing with creatine causes more water to be retained in your muscles, and thus causes some (superficial) weight gain. It's not uncommon to gain 5-15 pounds over a short period while taking extra creatine, due to increased water retention. So, in this case, you can sort of gain several pounds of weight by taking much less than a pound of a supplement.

I'm sure there are other nutrients/chemicals that cause water retention as well. I think salt may be one.

But, like I said, you'd have to actually intake the water as well, the body doesn't create something out of nothing.
posted by Diplodocus at 5:29 PM on February 23, 2010


I am not at all a nutritionist. But logically addressing this problem, setting aside all science for a brief moment, I don't see how it is at all possible to gain more than one pound after ingesting one pound of food.

If you took the piece of cheesecake and put it on a scale and it weighed one pound, if you eat it, you should also gain one pound **immediately after eating it.** Which is to say if you weigh yourself before eating cheesecake and you were 185 lbs , than right after the last bite you should be 186 pounds.

Now I do know a few things happen when we eat. The very action of digesting food consumes energy which burns calories. Hence eating a stick of celery is a nice snack because you burn most of the calories just chewing the celery stick. I also know some of the food is converted to energy to fuel cells. Some of it is stored as fat (in the case of a cheesecake, probably most of it), and the rest is converted to waste.

Let us assume that we ate enough to perfectly balance our daily caloric needs. It stands to reason that if we ate a pound of cheesecake, and that serving is 1460 calories, a little more than a half pound of that cheesecake over the course of the day would convert to energy via the digestive system. Which would suggest at a later time of the day, by just living, you would weight 185.5 pounds. Then some of the remaining 1460 calories would be stored as fat, while the rest is converted to energy, or excreted as waste. Thus when everything is said and done, you may have only increased a net .3 lbs (again, these numbers are for arguments sake). So it would seem to me that it is very unlikely, if not impossible to gain more weight than you ingest. Weight gain comes from constantly eating beyond your daily caloric limit, which for someone of average height and weight is around 2100 calories a day. So if that person ate 3500 calories a day, they would gain a pound about every 2 or 3 days. If the same person burned the 1400 excess calories a day they would gain no weight.

my $0.002
posted by FireStyle at 6:44 PM on February 23, 2010


Cool Papa Bell: Now, put one pound of stuff in the box and set it on fire. When it stops burning, weigh the box. It will be heavier than when you started, but it will not be more than one pound heavier.

Not all stuff behaves that way. Ever tried burning magnesium?
posted by teraflop at 7:32 PM on February 23, 2010


Not all stuff behaves that way. Ever tried burning magnesium?

You mean magnesium doesn't burn? You mean when you apply a heat source and oxygen it doesn't release a lot of heat and light and smoke and leave behind an ashy residue? Holy shit! Somebody ought to tell these people they're lying to the students in that classroom! Have you considered adjusting its Wikipedia entry?
posted by Cool Papa Bell at 8:03 PM on February 23, 2010 [1 favorite]


You mean magnesium doesn't burn?

It seems obvious that what teraflop is saying is that if you burn magnesium in a bowl, after you're done burning it it will weight more. Because magnesium is 24.3 grams per mole, and if you burn it you are ADDING OXYGEN TO IT, so the mass of magnesium oxide is 40.3 grams per mole, which is exactly what you'd expect given the atomic weight of oxygen.

Many things seem to weigh less when you burn them because their combustion products are gases and so escape. But for any chemical, when you burn it by adding oxygen to it, you are increasing its mass.
posted by ROU_Xenophobe at 8:51 PM on February 23, 2010


Yes, that's what I was trying to suggest. Sorry it came out more oblique than I intended.
posted by teraflop at 9:54 PM on February 23, 2010


Well, you're right in the physics sense: There is no magic "mass factory" inside the body, so adding a pound of weight will require adding a pound of inputs (which include "thin air" and water).

As for practical consequences, I assume your sister is a) wrong for all purposes likely to appear in everyday life, since fat is just so damn nutrient-dense it's very hard to beat and b) right in constructed cases where part of the marginal extra pound enables you to metabolize more of all the _other_ pounds of inputs you add.
posted by themel at 1:46 AM on February 24, 2010


You already acknowledged the water gain loophole, but just to make it explicit: when you store carbs in the form of glycogen in the liver and muscles, there is about a 1:3 ratio of glycogen to water required. So say that you've depleted your glycogen stores (either you're on a ketogenic diet or you've just done a couple hours of long cardio) and you eat 100g of carbs, your body will also bind about 300g of water in order to convert and store those carbs as glycogen. So in that sense there can be a multiplication factor, but of course you also put that water in your mouth so it's not like the mass is coming from nowhere.
posted by Rhomboid at 2:03 AM on February 24, 2010 [2 favorites]


Now, put one pound of stuff in the box and set it on fire. When it stops burning, weigh the box. It will be heavier than when you started, but it will not be more than one pound heavier.

This is disengenuous, either the box is sealed and there is only one pound of all materials inside prior to combustion, including oxygen, in which case you get very (very, very) slightly less than one pound of all materials afterwards, or the box is not sealed in which case oxygen gets in and CO2 escapes in which case the box will weigh less, either way, no weight increase.
posted by biffa at 4:18 AM on February 24, 2010


It's an interesting question, because there are 2 scenarios being confused here.

1. Your sister eats a 1lb cheesecake and nothing else until it is completely digested and excreted. In this scenario, I think it's very unlikely that the elements of the cheesecake react chemically with her stomach acids and increase in mass as a result to more than 1lb stored body fat/muscle. I don't know if such a chemical reaction is possible in the body.

2. Your sister has an exact diet which results in a steady state of neither losing nor gaining weight. She additionally eats a 1lb cheesecake one day. This is more realistic and could very well result in more than 1lb gained by changing the way the other foods are digested and metabolised. It's "as a result" of eating the cheesecake, even if the additional pound of weight is not necessarily from the cheesecake atoms themselves. Perhaps this is what she means!
posted by dave99 at 4:37 AM on February 24, 2010


Here's a question for the biologists/biochemists if there are any here. The most calorically dense foodstuff known is fat, which we've already discussed as 9 kcal/g. The conclusion we've come to based on that is that eating 0.85 lb of fat (e.g. lard) could (if hydrogen and oxygen atoms from the air/water/etc. were added) result in a gain of 1.0 lb.

Here's my small issue- from my limited knowledge of biochemistry, the fat in question (e.g. lard) is quite chemically similar to the fat that might be stored as in the human body. I recognize that these fats are broken down chemically and rebuilt from scratch, but if there's extra mass for the same amount of stored energy, that means there must be extra mass (i.e. extra atoms). Are the lipids in question longer hydrocarbon chains? If so, there needs to be a source for the extra carbon, presumably from something else consumed. Or, are we talking about water molecules/etc. within the fat?

Perhaps we should be accounting for carbon rather than mass?
posted by JMOZ at 5:13 AM on February 24, 2010


Many things seem to weigh less when you burn them because their combustion products are gases and so escape. But for any chemical, when you burn it by adding oxygen to it, you are increasing its mass.

Except for all the light and heat and gases that escape during the burning process. I don't see why people can't seem to understand this analogy. We eat stuff so we can create energy and heat move around and type things on the Internet.

This is disengenuous, either the box is sealed

The box, as an analogy to the human body, is not sealed. Heat escapes, just as it does with your own body. Or didn't you notice your warm, comfy bed last night?

or the box is not sealed in which case oxygen gets in and CO2 escapes in which case the box will weigh less, either way, no weight increase.

Which is exactly what I said. So, stop tossing around words like "disengenuous," which imply someone is lying.
posted by Cool Papa Bell at 7:48 AM on February 24, 2010


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