When You Lose Weight, Where Does It Go?
mitchkirby.wordpress.com
mitchkirby.wordpress.com
I'm an MD. I don't remember this specific piece of information being mentioned during my training. However, all the information need to reason about it was included...
What really blows my mind is how many people get it wrong, including my colleagues and especially dietitians ("they had one job").
It's only Hydrogen... But it still needs to go somewhere. Oxygen comes in to carry away the Hydrogen as water--you can't urinate Hydrogen.
"It is difficult to get a man to understand something, when his salary depends upon his not understanding it."
That is fairly astounding... I'm a paramedic and while I don't recall talking about this specifically, the answer was immediately obvious from the (comparatively limited) amount of A&P training we receive.
I would more chalk this up to too little biology, too late, for people to learn well. And, frankly, it's not something everyone NEEDS to know; misunderstandings are not the end of the world.
Still, we don't normally assume that water is the primary component of "soil". The key realization is that a tree is not made of the dirt around it.
I think many people interpret it as "Why do I lose weight?" or even "Where does that fat go when I lose weight" and answer correctly: your body uses up your fat stores as fuel when there's no easy sugar available. Calling that a wrong answer is a bit unfair, there's nothing technically incorrect about it.
However, that's not what was asked - the question is where does the mass go? After all, if you light a fire inside a box, the box doesn't get lighter.
The trap is that there are by-products from the chemical reactions which have to go somewhere, and that somewhere is typically through respiration (and excretion).
"(So wrong. Mass cannot be converted to energy except through nuclear reactions)"
This is, of course, wrong. All energy has mass. A charged battery has more mass than an empty one. A chunk of fat weighs more than all of the byproducts that come from metabolizing it.
It's almost true, because the conversion factor between mass and energy is huge, so the change in mass for more mundane quantities of energy is far below what's reasonably possible to measure. But there's nothing special about nuclear reactions aside from the quantity involved.
The mass of the fuel in your gas tank is pumped into the atmosphere as CO2.
But it clearly says that exercise combined with diet changes is better than either alone.
http://www.cochrane.org/CD003817/ENDOC_exercise-for-overweig...
> The results of this review support the use of exercise as a weight loss intervention, particularly when combined with dietary change. Exercise is associated with improved cardiovascular disease risk factors even if no weight is lost.
http://physics.stackexchange.com/questions/2605/how-does-mas...
I was suprised this was not linked in the post.
6,000,000,000 * 2,000 = 12,000,000,000,000
But wait, those are Kcals.
6,000,000,000 * 2,000,000 = 12,000,000,000,000,000
1 calorie is the energy required to raise 1 gram of water 1 degree C. There are about 4404.8838 grams in a gallon.
12,000,000,000,000,000 / 4404.8838 = 2,724,248,934,784.61
So this is enough to raise 2 trillion gallons 1 degree, or raise 1 gallon by 2 trillion degrees Celcius.
2,724,248,934,784.61 / 100 = 2,724,248,934.78461
Or boil away 2 million gallons of water. Per day.
While I thought the current estimates were closer to 7.1 billion. Though I doubt those 7+ billion people eat 2000 calories per day. When you consider how many people are starving in the world, I am not sure if its offset by the overeating overweight nations.
tl;dr; why 6 billion?
http://www.boston.com/bostonglobe/ideas/articles/2010/02/28/...
While looking this up, I came across the craziest sentence in the Wikipedia article:
"German physiologist Friedrich Goltz demonstrated that a frog that has had its brain removed will remain in slowly heated water, but an intact frog attempted to escape the water when it reached 25 °C."
Apparently this isn't quite as crazy as it sounds, as the brainless frogs still exhibit some reflexes, to the extent that they'll jump out of hot water. But still, it reads like a study in "WTF did you expect to happen?!"
Often we all assume something and so no one really investigates it properly. Science must concern itself with things we think we know are a priori truths in order to provide a solid basis for building on.
That said Goltz experiment seems quite reasonable to me, ~"do frogs have non-brain based reflexes that react to temperature?", ~"do frogs react to absolute temperatures or just changes in temperature".
https://archive.org/stream/studiesfrombiol00martgoog#page/n4... at p.389 suggests that the frog with "no cerebrum" is in some way alive in Goltz experiment - perhaps it is missing that point that makes you say WTF?
It seems the excitability of headless frogs in varying temperatures was quite a point of interest, see eg p.393 ibid.
Enhancing that seems like it would lead to a lot of discomfort for a little gain.
Your epidermis grows at a specific rate and will not really grow faster if you remove it. If you remove it faster, you will develop scar tissue, which is not desirable.
An interesting way to remove fat is lactation. It is the only biologically "native" way to directly remove lipids. Unfortunately this is only available for lactating females.
O₂ in, CO₂ and H₂O out
I thought of it upon seeing the first chart in the BMJ article.)
This is not true. There is energy in chemical bonds, and that energy is released when the bonds break. When you burn gasoline, the mass of the resulting molecules adds up to less than the mass of the original gasoline. A tiny, tiny fraction less, but still less. Because there was energy in those bonds, and energy has mass.
It's wrong in another way, too, because even in nuclear reactions mass isn't converted into energy. Mass is mass, but energy also has mass. No mass is lost in a nuclear (or chemical) reaction, it just goes somewhere else. There is no "conversion" going on.
Thinking now I suppose an [close] equivalent is probably can you increase carbon dioxide production by increasing oxygen saturation of the air inspired?
There's probably enough in that idea to sell oxygen masks and little tanks and a book for a new fad 'diet' ...
I suppose the act of breathing itself would burn more calories, but it isn't the most challenging exercise, not to mention the dizziness mentioned already.
[1] answers a lot of this.
Again with presumptions from biological ignorance, in low oxygen environments it seems we can't "burn" so much food, so oxygen saturation is definitely a limitation. Also we know that oxygen saturation varies, so even if STP oxygen percentage of air is the optimum sometimes we'll be sub-optimal - how does the body cope then?
[2] appears to answer that one.
What I take away from that, wrt my enquiry, is that under increased breathing [hyperventilation] renal compensation can kick in to combat the alkalemia caused by the respiratory alkalosis [reduction of available H+ ions in the blood, ie alkalination or increasing of pH] by extracting extra-cellular fluid bicarbonate [HCO3-, see [3]] and excreting it in urine.
Now I'm moving back up the pathways, is renal compensation deleterious (and at what point is that true). Does low level alkalosis with renal compensation cause an increase in removal of food products from the body?
At least it seems that we now have created an increased carbon removal by excreting HCO3- in urine!? [how much?]
So is there an increase in breathing frequency that maintains normal function, not "hyperventilating" (in the common usage of the term, that makes you dizzy), that doesn't cause harm? The question still stands I feel.
Also can you do something else that causes acidosis and cancel it out by increased breathing?
Apologies again, I'm clearly fumbling around here but I've not studied biology since I was 13 (decades ago).
- - -
[1] https://en.wikipedia.org/wiki/Respiratory_acidosis#Mechanism
[2] https://en.wikipedia.org/wiki/Metabolic_alkalosis#Compensati...
[3] http://web.archive.org/web/20070930080050/http://www.lib.mcg..., via Wikipedia https://en.wikipedia.org/wiki/Renal_compensation
I think altitude sickness would be the result, not enough oxygen.
Someone else has noted respiratory alkalosis as a limiting factor, but that again is seemingly an extreme.
When your cells are breaking down sugar into energy, if you have enough oxygen readily available then you can extract more energy per molecule of sugar. If you're burning sugar anaerobically, then you won't be able to make the full use of the sugar, and thus the byproducts will get excreted with less work required.
>the byproducts will get excreted //
How?
Also, I was mistaken somewhat, the byproducts aren't excreted, they're reprocessed in the liver back into glucose, but this requires extra energy. So it's less efficient than aerobic respiration, but not by as much as I believed.
Fat is some complex molecule made up of a bunch of carbons, hydrogens, and oxygens. Where do you think these atoms go?
The short of it is the fat molecules are turned into other molecules (which gives you energy) with the addition of oxygen, and the byproducts (water and co2) are expelled as a byproduct.
They just grow and shrink in size.
> This analysis makes it clear why exercise is so powerful in the weight loss equation.
There are many reasons to exercise, but it's quite clear weight loss isn't one of them. I mean, you need to exercise to get your abs to pop, but not being a lard-ass is totally about avoiding excess calorie intake and exercise really doesn't enter into it. People don't realize what a trivial amount of calories working out burns.
One problem with exercise isthat it doesn't burn many calories, and some people "reward" themselves for doing that exercise with an extra bit of cake.
If you walked at 2.5 MpH and weighed 160 pounds, it would take you two and a half hours to burn your 500 calories. To me 2.5 hrs is not an "easy" workout. Somewhere between medium to hard (depending on fitness level).
A single Big Mac is almost 500 calories, two snickerdoodles are more than 500 calories on average.
> Of course it's not a substitute for a proper diet, but it can be a huge factor in weight loss.
That's just not true.
A single combo from McDonalds could set you back an entire weeks worth of exercise, literally. If you exercised for an hour a day every day, it only takes a single meal to undo most of that weight loss.
PS - Exercise is, of course, very important for overall health and a long life. Nobody is arguing otherwise. But for weight loss? Heck no. The maths simply doesn't work at all.
A 160 pound person could burn 500 calories in ~40 minutes jogging at a 10 minute per mile pace, and could easily offset a Big Mac in a single day's exercise (not saying that the person should use this to justify eating a Big Mac).
One hour of squash burns 600+ calories. One hour of running burns 600 ish calories. One hour of cycling burns something like 400-500 calories.
No citations for these figures, just going off memory
Burning 500+ calories per session is definitely doable - if you are doing the right exercise in the right ways for the right duration.
Not really. Probably even a bit the opposite. If you exercise hard daily the resting metabolic rate actually drops some as an adaptation to conserve calories: exercise induced hypothyroidism. Pro level cyclists have to count calories to keep their weight down and they don't eat nearly as much as you'd think.
Muscle mass preferentially burns fat, so you get a very small metabolic edge from having some extra muscle, but not much. Adipose tissue also burns a great deal of calories, believe it or not, so getting really fat is a good was to increase your metabolism. This is why when obese people start restricting calories the first 30 pounds or so pretty much melts off with not much difficulty.
http://www.cochrane.org/CD003817/ENDOC_exercise-for-overweig...
> The results of this review support the use of exercise as a weight loss intervention, particularly when combined with dietary change. Exercise is associated with improved cardiovascular disease risk factors even if no weight is lost.
cbass.com has this stuff dialed in. One im-gonna-puke strength session a week and one difficult endurance "cardio" session makes a ton of sense to me, when you take in the literature. Much more and exercise starts to look like a net negative in many ways. Suggesting to a fatty that they jog five times a week is at best a waste of time and at worst actively harmful.
You? My neuro-atypicality means I geniunely don't know if you're trolling and yours is a parody post, or if you actually think cbass.com - a comercial site selling get fit quick dvds and books - is a reputable cite.
One question: if they have it "dialed in" why are they selling ten different books?
Anybody who's actually tried, and succeeded, in losing weight and keeping it off will tell you that diet is way more important than exercise when it comes to fat loss. Exercise absolutely produces health benefits, but they are largely orthogonal to the ones produced by changing how you eat. If you can do one but not the other, then diet.
Most people with a lot of weight to lose have willpower problems, that's why they have a lot of weight in the first place. Not all, but most. These people are better served conserving their willpower and taking more effective courses of action than the one they can't take. (both diet and exercise)
http://www.amazon.com/Why-We-Get-Fat-About/dp/0307474259
The third chapter is all about why exercise isn't a good way to lose weight. It is generally a fantastic book.
Also consider... I'm a 33 year old 215lb man. An hour at the gym lifting weights is about 340 calories, or approximately the amount of calories you get by drinking a couple glasses of soda at lunch and dinner. You need 10 trips to the gym or 10 days without soda. Assuming you go to the gym 3 days per week, that's 3 weeks of exercising compared to 1.5 weeks of drinking water instead of soda.
I think it's more that people don't realize how stunningly high calorie counts for "bad" food can be. Like a cookie might take 20 minutes of exercise to burn off the calories, but that's more about the cookie than about the exercise.
Undeniably there are artificial foods with insanely high calorific levels for either their volume or weight. But all foods are inherently hard to burn off via exercise. Some are just worse than others.
I wish I found it as easy as that.
I'm a couch potato, I can burn about 300 cals per half-hour (according to the stationary bike machine or elliptical). In my better days, that was up to 350 cals per half-hour, I was quite fit but not athletic.
So no, your 45 minutes of HIIT isn't burning 1000 calories, and if calories are your goal, you would obviously not be doing HIIT in the first place (what's the point in getting nauseous when you can just produce these steady watts).
(That said, I still heavily disagree with the grandparent; exercise is as much part of a diet as is calories in / out. If you can do 150W for a grand total of 5 hours every week, that totals 2500kcal or more than an extra days worth. For many people, time spent exercising is also time spent not sitting idly in front of a TV and eating.)
More importantly, however, http://www.ncbi.nlm.nih.gov/pubmed/15241718 finds no differences in efficiency between world-class and recreational cyclists.
In any case, the "cycling" bit is somewhat of a smoke-screen; it just so happens that it's most easily measured and objective data has long been available through power meters. There is no free-lunch, regardless of the particulars of any sport.
(I should however probably clarify that the power numbers quoted above are mechanical power as measured during cycling, which is pretty much the only sport that even has ways of measuring power reliably)
This is wrong enough to make me stop reading.
EDIT/replying:
I'm inclined to continue to believe that it can't in any other way.
1. Not through a chemical reaction; energy can be released in a chemical reaction, but the total mass/atoms involved remains the same.
2. Not through kinetics; energy can be produced, but mass remains the same as well.
cf. some interesting caveats here http://en.wikipedia.org/wiki/Conservation_of_mass
Q is the released energy. If you weigh the molecules before and after very carefully, you will notice that they lose weight (or mass if you are being pedantic about it). That mass loss corresponds exactly to the Q-value (through E=mc²).
Any mass gained or lost will be due to changes in bond energies, and the corresponding emission or absorption of photons that change the energy states of the electrons in the bonds.
If you measure the mass of a quantity of water accurately enough, the mass will be lower than the mass of the equivalent amount of hydrogen and oxygen gas. The difference would be so small that our most sensitive instruments would not be able to detect it.
Likewise, in a nuclear reaction, the only thing changing is the nuclear binding energies of the protons and neutrons. However, since the energy involved is many orders of magnitude higher, our instruments are sensitive enough to detect the difference in mass.
If you walk up a flight of stairs, you will be heavier at the top. If an electron changes orbital, its mass changes as well, making it heavier or lighter.
Let's calculate it. A 90 kilogram man walks up a flight of stairs, one story (3.3 meters). The expression "m * g * h" gives us the gravitational potential energy of mass "m" ascending height "h". Evaluating the formula we get 2910 joules. So how much heavier has the man become? Given E=mc^2, then m = E/c^2. As you can see, we'll be dividing by c^2, which is a very big number. The resulting increase of mass is 3.24 E-14 kg, or too small to be noticeable, but still very real: A 90 kg man ascending a 3.3 meters gains 0.00000000000003 kilograms of mass.
Chemical potential energy changes result in mass changes as well. These changes in mass are insignificant at the scale of chemical reasons, but are indeed taking place. So while it may be reasonable to simplify a discussion of chemistry by saying that chemical reactions don't change mass, in reality the changes do take place, just at a very small scale. A starting point for further research:
"Whenever any type of energy is removed from a system, the mass associated with the energy is also removed, and the system therefore loses mass. This mass defect in the system may be simply calculated as Δm = ΔE/c^2"
https://en.wikipedia.org/wiki/Mass%E2%80%93energy_equivalenc...
Someone else can calculate the decreased buoyancy in thinner air ;)
Edit: Notice I put mass in quotation marks. I am not trying to break the law of conservation of mass. Fat cells consumed will produce energy through some kind of biological process.
This is only approximately true. It would be hard to measure the difference, for sure. Relativity gives a lot of seemingly bizarre results:
* If you carry something uphill, it gains mass as you go. (Kind of... consider that it is part of a system which includes the Earth.)
* If you compress a spring, it gains mass.
* If you charge a battery, it gains mass.
* If you fire a laser into space, it will have a longer wavelength when it gets there.
* If you hook a shaft from the ground into space and turn it, it will turn faster at the bottom and slower at the top.
We live in the "middle ground" which is well approximated by Newton's laws. Strictly speaking, Newton's laws are false.
Does a block at rest sitting on the top of a hill have more mass than a spinning block at the bottom of a hill (assuming the rotational kinetic energy equals the difference in potential energy)?
Since the energy can end up anywhere and the energy has mass, the mass can end up anywhere, too.
If you take a block of steel from the top of a hill to the bottom of the hill and convert all the potential energy to kinetic energy (without loss), why would the mass of the block be altered? It may well be true, but arguments based on applying the mass-energy equivalence is not the answer.
Likewise, if you start with some pool of molecules and rearrange the constituent atoms and bonds, energy must be balanced via kinetics (i.e. translational and rotational energy of and within molecules on both sides of the reaction)--why should anyone expect the overall mass to change from such chemical reactions?
Note: this amount of mass is very small and so is typically left out of introductory chemistry courses.
For example, a person consumes approximately 2000 kcal/day of food. The calculation is more complicated, because not all the energy is used. But for the sake of the argument, let's assume that the person just use all the 2000 kcal and they are lost as heat, work (lifting a heavy object , moving the air, moving the water while swimming, ... )
Using the famous E=mc^2 equation we have that m=2000 kcal/c^2 = 9E-8 grams = 3E-9 ounces. That's very small and is not useful for a diet, but it's not zero.
That's the kind of thing that might make people want to stop reading.
Example:
You have some fissible material that undergoes a nuclear reaction in a closed system and the reactants turn into products with lower mass.
The mass of the system doesn't actually go down until/unless the system cools down.
edit: The above commenter is still being pedantic though
Yes, it's quite true that in physics, mass cannot be turned into to energy. But the article's not talking about physics; it's talking about biology, and in biology, fat can be turned into energy --- that's why your body makes it.
Yes, of course it's not a nuclear process. The fat's metabolised into energy and waste products, which are excreted mostly through the lungs. Also via the skin, urine, faeces and any other bodily fluid --- one byproduct is water.
'It's turned into energy' is actually the right answer if you're thinking about biology. It's just not a complete one. The article would have done much better to have instead said 'you're right, but' and then gone on to explain, rather than just saying 'if you think this you suck'.
The picture changes when you're down to those last few pounds. To get those off, you have to keep up the reduced caloric intake, and you also have to exercise. If you slack off on the former, you'll gain weight back. If you don't exercise, you won't lose any fat.
Building habits and willpower is a journey that takes at least a year and involves changing your relationship with food. To a large extent, we see food as entertainment, it takes a long time before our subconscious minds' adjust to thinking about it as fuel. Inherent in this is replacing that hole left in our psyches where food entertainment used to be with something else as entertainment.
It was a whole year after I started dieting before I started looking at salads as a perfectly acceptable lunch, perfect for getting a feeling of fullness without blowing up the calorie meter. For a long time I played this game of trying to get the most value out of my calorie budget, still mind thinking of food as entertainment.
I did intermittent fasting, which was effective at helping me lose weight but not at keeping it off because it didn't solve the food-as-entertainment issue. Once I got down to a more reasonable weight I stopped, and before I knew it I was fat again, though not nearly as fat as before. I hadn't stopped thinking of food as something to cure boredom with.
I eat better than I ever have, and look more youthful at 31 than through most of my twenties. Ironically, I feel I also enjoy food a lot more than I used to. I taste it better, I find it more interesting. In a Buddhist non-attachment sort of way.
you heard it here first.