When somebody loses weight, where does the fat go? BMJ article.

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  • When somebody loses weight, where does the fat go? BMJ article.
  • This is interesting, not just because I learnt something, but because so many other people who ought to know the correct answer, don’t.

    Responses of a sample of doctors, dieticians, and personal trainers to the question β€œWhen somebody loses weight, where does it go?”

    http://www.bmj.com/content/349/bmj.g7257

    Stoner
    Member

    C55H104O6+78O2?55CO2+52H2O+energy

    Stoichiometry shows that complete oxidation of 10 kg of human fat requires 29 kg of inhaled oxygen producing 28 kg of CO2 and 11 kg of H2O. This tells us the metabolic fate of fat but remains silent about the proportions of the mass stored in those 10 kg of fat that depart as carbon dioxide or water during weight loss.

    Must breathe more.

    This is of related interest too.
    I already knew that the mass of a tree was made up of air, I just never figured out that the mass of animals was turned in to air.

    [video]https://www.youtube.com/watch?v=2KZb2_vcNTg[/video]

    Premier Icon Drac
    Subscriber

    Ermmm! Come on really that’s the figures of those that didn’t know?

    That said oxidation is the burning process of the fat so really that’s why some would say turned into heat and energy. The answer of it’s breathed out is the final state of the process, so it’s all about how the question was interrupted.

    cheez0
    Member

    Heheh.. your dyslexic spellchecker has produced a classic, Drac!

    WackoAK
    Member

    Can someone actually explain for the thickos what is being said in the article?

    “eat less, move more” was what I gained from it?

    Premier Icon Drac
    Subscriber

    Heheh.. your dyslexic spellchecker has produced a classic, Drac!

    I can’t even see it yet, I will later when my brain switches again. 😳

    Can someone actually explain for the thickos what is being said in the article?

    That we breathing out is the largest excretion of waste products. You know something a 13 year old learns in biology. But by wording a question badly they’ve tried to trick GPs to make a shite article.

    Drac, perhaps they gave the wrong answer because the person asking was interrupted while speaking. πŸ˜‰

    Can someone actually explain for the thickos what is being said in the article?

    If you are a personal trainer, no need to diet, just take a dump.

    hilldodger
    Member

    To calculate these values, we traced every atom’s pathway out of the body

    I really don’t think they did πŸ˜•

    Most people believed that fat is converted to energy or heat, which violates the law of conservation of mass

    law of mass conservation applies only to a closed system, which the human body quite obviously isn’t

    CBA to dissect out all the other errors and misconceptions

    Agreed it is a poorly worded question with no clear definition of what “weight” is, so open to different interpretations.
    Perhaps asking where the fat molecules go would be a better question.
    Even so, as someone with limited biological knowledge, it came as a surprise to me.
    It’s not something I’ve ever thought about all that much before, I suppose I just assumed that as fat people lost weight, they would have very fatty poo.
    I wouldn’t have immediately guessed that the individual hydrogen, carbon and oxygen atoms in solid fat got recombined in to gas, even though I already knew that trees make wood out of gas.

    ton
    Member

    fat is fuel……….infact fat is the best fuel for endurance sport.
    it melts like long burning engine fuelling goodness.
    embrace the fat………. πŸ˜€

    teasel
    Member

    embrace the fat

    I would but I’m not keen on the additional hair.

    Oh…

    Premier Icon Drac
    Subscriber

    Drac, perhaps they gave the wrong answer because the person asking was interrupted while speaking.

    Hahaha! And now I see it. πŸ˜†

    Even so, as someone with limited biological knowledge, it came as a surprise to me.
    It’s not something I’ve ever thought about all that much before, I suppose I just assumed that as fat people lost weight, they would have very fatty poo.

    Think of the body as an engine, the exhaust is resp system, oil is the blood and gastric system. Where does diesel go when we burn it?

    Fatty poos are a rather unpleasant sight. πŸ˜₯

    nick1962
    Member

    I was always under the impression that when someone lost weight someone else put weight on.My bad science,matter cannot be created or destroyed just shuffled from one person to another.

    Premier Icon MoreCashThanDash
    Subscriber

    nick1962 – hence when someone tells me they have lost weight, I pat my stomach and tell them that I think I have found it.

    Premier Icon Drac
    Subscriber

    law of mass conservation applies only to a closed system, which the human body quite obviously isn’t

    Exactly, we’d not be much use if we didn’t burn food and fats into energy each day.

    Premier Icon maccruiskeen
    Subscriber

    Think of the body as an engine, the exhaust is resp system, oil is the blood and gastric system.

    I’ve got a dipstick.

    And a big end.

    Premier Icon ac282
    Subscriber

    If we really did turn mass into energy it would take a long time to get rid of 10kg.

    law of mass conservation applies only to a closed system, which the human body quite obviously isn’t

    Isn’t that the point though?
    The body is obviously not a closed system because it’s mass has reduced, therefore that mass has gone somewhere outside the system.
    It’s the fact that a solid mass, fat, has left the system as a gas that I find surprising when I wouldn’t normally think of breath, the gas in question, as having significant mass in itself.

    66deg
    Member

    Think of the body as an engine, the exhaust is resp system, oil is the blood and gastric system.

    I’ve got a dipstick.

    And a big end.

    I think mine might be getting a service tonight. πŸ˜‰

    MTG – Don’t forget trees are made of sunshine too.

    I’m surprised your surprised: what do you think happens to petrol?

    Trees are made of sunshine?
    How do they turn light in to mass? πŸ˜‰

    Yes, petrol, or any other solid or liquid fuel, gets turned in to gas when burnt. I’m surprised you’re surprised that I’m surprised to find that something similar is going on inside me right now.

    hilldodger
    Member

    If we really did turn mass into energy it would take a long time to get rid of 10kg.

    Only if you’re thinking in terms of atomic rather than chemcal energy

    Premier Icon ir_bandito
    Subscriber

    no need to diet, just take a dump.

    That’s my favourite bike weight saving suggestion.
    Spend Β£X00 on components to save x00g? No, just do a poo.

    Premier Icon maccruiskeen
    Subscriber

    so many other people who ought to know the correct answer, don’t.

    You say they ‘ought to know’, but they don’t need to know and knowing or not knowing has no consequence to the job they have to perform. They need to recognise a condition, undertake a correct course of action and unsure the patient responds as anticipated. It doesn’t matter where the fat goes, the fat isn’t the patient once its gone.

    By using it to form bonds in carbonhydrates πŸ˜‰ πŸ˜‰

    The energy has no mass in itself however the without that energy they wouldn’t be able to perform the hydrolitic reactions necessary to produce the carbohydrates they then polymerise into the ceullolose and starches that make up the majority of their solid mass. Smart arse.

    Premier Icon maccruiskeen
    Subscriber

    something similar is going on inside me right now.

    mind you don’t follow through

    Premier Icon miketually
    Subscriber

    More interesting ‘biology’:

    The oxygen atoms you breath in leave your body in H2O in urine. The oxygen atoms you eat leave your body in CO2 when you exhale.

    DrP
    Member

    I like (as in, it’s an interesting, pleasant concept) explaining to people that for every kg of fat they ‘lose’, they’ve actually breathed that kg out as waste gases πŸ™‚
    Patients really like that idea too!

    DrP

    So that’s where the phrase “heavy breathing” comes from.

    In a similar, but different, vein, why does eating a cream cake that weighs an ounce or two make me put on pounds? Am I some miraculous machine that can create mass?

    Premier Icon wors
    Subscriber

    So, losing weight is contributing to climate change πŸ˜†

    footflaps
    Member

    Most people believed that fat is converted to energy or heat, which violates the law of conservation of mass

    So if I set fire to a pound of butter I’m breaking the laws of physics?

    Premier Icon miketually
    Subscriber

    So if I set fire to a pound of butter I’m breaking the laws of physics?

    No, but you’re not converting mass the heat either.

    vickypea
    Member

    I don’t get why it’s a news item. I thought it was obvious 25 years ago at university.

    brocks
    Member

    It’s news to me and many others smart ass some people on here didn’t go to uni, don’t like smug!

    vickypea
    Member

    I’m talking about why it’s in the NEWS, not why it isn’t obvious to people who haven’t studied biochemistry. Nothing to do with being smug.

    The article was only published three days ago. How could you have known about it 25 years ago?
    There’s a difference between information being news and a study in to people’s knowledge of that information being news.
    Didn’t they learn you nothing at university? πŸ˜‰

    klumpy
    Member

    Seems a bit like arguing that a burnt log doesn’t turn into heat and light, but smoke and ash.

    Actually, it’s both.

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