35

Someone once told me it is possible to have a net weight gain of more than what you eat. For example if you eat a quarter pounder burger you can potentially gain more than 1/4 pounds. Is this true?

Sklivvz
  • 78,654
  • 29
  • 323
  • 429
Thomas O
  • 11,904
  • 7
  • 53
  • 72
  • 2
    Related: http://physics.stackexchange.com/questions/2605/how-does-mass-leave-the-body-when-you-lose-weight – Sklivvz Apr 30 '11 at 23:12
  • 46
    Evil plan: We could feed 1kg of lion meat to tigers, and get 2kg of tiger meat to feed to lions to get 4kg of meat, and... hey we just solved world hunger! – Sklivvz Apr 30 '11 at 23:45
  • 6
    You can, if you a) drink 2 liters of cola meanwhile or b) implement the opposite of nuclear fusion inside your body (see 'conservation of mass' @Purdy) E=mc². – user unknown May 01 '11 at 00:21
  • 8
    @user unknown: I was assuming for the sake of argument that nuclear fusion does not, generally speaking, occur within the human gastrointestinal system.

    ...Yet.

     – Jon Purdy May 01 '11 at 00:42
  • @Jon: I appreciated your answer, since it contains, what I would have answered, if you didn't came before me. I only wanted to point out, where the limit of the law of mass- (and energy-) conservation is. – user unknown May 01 '11 at 01:00
  • A more interesting question might be: Is it possible for a person's body to gain more volume than the volume of what they eat? I'm guessing the answer is yes, but it may be difficult to prove. – ESultanik May 01 '11 at 01:57
  • @ESultanik: It's not difficult at all: your intake just has to have an average energy density greater than your tissue does, accounting for energy lost through other functions. For instance, if I eat a diet composed exclusively of fats of higher density than human fat, I'll gain more fat volume than I consume. This might also work in the short term for a high-water, high-salt diet, but that's kinda cheating. – Jon Purdy May 01 '11 at 03:17
  • 3
    Maybe this is how the breatharians do it. – Kyralessa May 01 '11 at 03:41
  • 19
    Sort of. Everyone else has answered from the conservaton-of-mass perspective. However, a 1/4 pound cheeseburger is made from 1/4 pound of meat, ergo the 1/4 lb. does not include the bun, cheese if you like, lettuce, tomato etc... Therefore, it is theoretically possible to gain more then a 1/4 lb. from eating what is commonly referred to as a "1/4 pound hamburger", but that is simply because the assembled hamburger itself weights more then 1/4 lb. – Fake Name May 01 '11 at 08:33
  • 6
    The other answers here are not considering the water that you drink. You are 65-90% water, but a cheeseburger is probably around 30% water. So, you have to count the water you drink with your cheeseburger. – Neil G May 01 '11 at 07:12
  • 2
    Yes, if you eat the burger on the moon and then travel back to earth you will weigh more. But don't blame it all on the burger ;) – Oliver_C May 01 '11 at 09:26
  • 1
    @Jon Purdy: It's not quite that simple: The body doesn't necessarily metabolize 100% of the fats that one eats into human fat. – ESultanik May 01 '11 at 19:17
  • @ESultanik: Right, I was heavily simplifying; I did cover myself by mentioning the necessity of "accounting for energy lost through other functions", though. – Jon Purdy May 01 '11 at 22:01
  • 1
    Not if you cook it! 1/4lbs is the weight before cooking. – Tester101 May 03 '11 at 16:53
  • 1
    I would point out that yes. You can gain more than what you eat: Drink a gallon of water and eat nothing. +8 lbs. – KitsuneYMG May 05 '11 at 14:23
  • @FakeName, More specifically, it's 1/4 of meat before cooking. Some of that weight is lost to the grittle. – Brian S Sep 03 '14 at 18:12
  • 2
    Is "someone" now considered notable? Who exactly is making this claim? Sounds like a candidate for closing. – John C Sep 04 '14 at 12:23
  • "someone" is not notable, but it is evident from a quick google search that a lot of people have this doubt. – Sklivvz Sep 04 '14 at 14:06
  • 1
    I'm pretty new here. Would it be reasonable to interpret this question as "will you gain more weight in the long run", with the idea that maybe there is some kind of food that causes the body to hold on to other kinds of food longer? Like say if there were some magic chocolate bar that liked sticking to the human body and sticking on to extra water, causing you to drink more water and then your net weight increase will be more than the weight of the chocolate bar? I'm thinking along the lines of a salt that sticks around for a long time? – raptortech97 Sep 10 '14 at 21:51
  • This really depends on how you define "eat": if you restrict it to solids taken by mouth, then it's trivially true (some of that water you drink ends up as body mass); if you define it as the total mass intake, then it's trivially false (conservation of mass). – Mark Jul 11 '16 at 00:38

1 Answers1

9

No.

This is because of something called ecological efficiency (or trophic level transfer efficiency). This is the efficiency with which energy or biomass is transferred from one trophic level to the one above it. This is virtually always less than 100%.

This is because biological organisms are not perfect converters (so the thermal efficiency is not 100%) and some energy is lost as heat, as well as the fact that not all energy can be used by the organism (it isn't in a form that can be digested completely or not fully bioavailable).

As a very rough average, only about 10% of the energy is kept as you go up to the next trophic level but this varies a bit depending on circumstances. This is e. g. why you need substantially more than 1 kg of grain to get 1 kg of beef.

So not only is it pretty much out of the question that you can gain more mass than you eat, it is also virtually impossible to gain as much as you eat, because some of that energy is lost as e. g. heat or used in basal metabolism.

Sure, you can invent fanciful situations with a high-tech, futuristic substance that has an enormous energy density and bioavailability while having a tiny mass, but for all practical intents and purposes, the answer is a resounding no.

References:

http://www.globalchange.umich.edu/globalchange1/current/lectures/kling/energyflow/highertrophic/trophic2.html

EmilKarlsson
  • 698
  • 7
  • 5