Dieting for Weight Loss - The Physics

Addressing heavily advertised Weight-Loss and Dieting Programs

  • Thousands of "experts" are constantly promoting a vast diversity of concepts regarding enabling or causing weight-loss.
  • Within a few minutes, you will know why most of them are not telling you the truth! And which of them you might be able to believe!
  • The core matter comes down to the fact that bodyfat is stored in the body as triglycerides (lipids) which are made up of roughly 40% carbon atoms.
  • In order to lose one pound of bodyfat, it does not matter what anyone tries to say, the body would have to get rid of around 0.4 pound of carbon atoms.
  • There is a basic scientific Law called Conservation of Mass, which means that the carbon cannot simply disappear!
  • It turns out that the human body essentially only has ONE way to dispose of unwanted carbon atoms, and that is to first oxidize it into carbon dioxide and then exhale it from the lungs.
  • So if there is food that has been digested, that is, which has become part of the body, it would not matter whether someone claimed to want to sell you a magic pill or magic food or some simple exercise equipment, NONE OF THAT could possibly cause any bodyfat to leave your body UNLESS you exhale a LOT of times!
  • The scientific calculations will be provided below which prove that roughly 26,400 normal exhaled breaths are required in order that the carbon atoms of one pound of bodyfat (or other energy sources) can be removed from your body. For comparison, in a normal day of normal breathing, we exhale around 15,000 times.
  • DEEPER and/or FASTER exhaling, often due to strenuous exercise, CAN cause more carbon, and therefore more bodyfat, to be eliminated from your body, but even that is far slower than the impressive TV commercials claim!

IF you take in more Calories (actually kilo-calories or Kcal) in a day than you use up, the excess energy is turned into sugars and fats, and eventually into fats called lipids or triglycerides, to be stored away for a possible future survival need, and you will gain weight. Equally, if you use up more Calories in a day than you take in, some of those existing lipids or triglycerides, fat and sugars is converted back into forms that can become energy, and some of the bodyfat are therefore converted into that work and weight is lost. The premise behind "working out" is closely related to this fact, and it would work to some extent, if it were not that all that exercise often creates a healthy appetite!

It is interesting that enormous numbers of TV, radio, newspaper and magazine ads talk about amazingly fast rates of weight loss, with some diet or some piece of exersize equipment! We tend to consume around 2200 Calories of food energy and use up roughly the same amount each day. It is rare when the difference, either way, is greater than around 200 Calories in a day. It also turns out that the sorts of exercises usually done at Health Clubs in working out, tend to rarely even double our normal body energy consumption of about 100 Calories per hour (thereby burning off only another 100 Calories per full hour of such exercise, again rarely more than 200 [extra] Calories burned off in such an extended workout session).

We note that bodyfat is a very compact source of energy supply (the whole point of it regarding survival!) and a pound of bodyfat contains around 3500 Calories of chemical energy stored in it. This indicates that two or three weeks are often likely necessary (3500 / 200 or about 18 days) to be able to lose even ONE pound of bodyfat! People who try to lose weight by dieting and/or exercise get frustrated at such slow progress! (For success, they must have immense patience and incredible dedication to the effort, both of which seem opposite of modern hurry-up and have-it-now attitudes!)

So TV and magazine and newspaper and billboard ads brag about losing 50 pounds in 50 days or something like that. Think about that. In order to lose 50 pounds of bodyfat in 50 days, it is necessary to lose or use up more than 1 pound every day. And such ads and concepts rarely also even attempt to get the person to also reduce the excess amounts of food they eat which caused them to become obese in the first place! If such a program could succeed, it would mean using up around an EXTRA 5000 Calories of energy from stored bodyfat each and every day. Even if the person did not eating anything at all for 50 days, the body's metabolism could only use up around 2200 Calories each day, where the actual total body weight loss would then be around 30 pounds in those 50 days! (Our bodies have an amazing ability to survive for many days when no food is available!) (By the way, people who go on long religious Fasts tend to lose MORE than this amount of total body weight, but that total loss also includes a large amount of WATER that is also lost in the process.) There is no easy way for our bodies to use up 5000 Calories per day! Do you see why such claims are exaggerations and/or misleading?

There is another way to look at all such claims. People selling such thihgs claim to make bodyfat "melt away" or equivalent, right? Bodyfats are all lipid or triglyceride molecules that are nearly completely carbon, hydrogen and oxygen atoms in complex combinations. You probably know of a basic law of science that says that nothing can either be created or destroyed (Conservation of Mass). Well, those lipids or triglycerides are commonly around 40% carbon. So WHERE does the carbon go? It can't just disappear! It must go somewhere! Can it VANISH in body heat? No, that would not account for the carbon atoms. Could it get excreted? No, because the digestive system is entirely separate from the body metabolic processes. You can rule out EVERYTHING, except for one thing! Your exhaled breath! Virtually the ONLY way that a human body can get rid of carbon atoms is to oxidized them into becoming carbon dioxide molecules, and then send them out of your body as exhaled air! Sadly, bodyfat can therefore never just "melt away"!

So, IF someone claims to cause bodyfat to be used up three times or ten times as fast as natural, they HAVE TO explain how THREE TIMES (or ten times) AS MUCH EXHALED BREATH had to also occur in order to carry the carbon atoms from all those bodyfat lipid or triglycerides molecules away from the body! Otherwise, all those carbon atoms have no easy way of going away!

There ARE a few very minor chemicals that get created which use up carbon atoms, but most of those stay in the body to be used for other purposes, and so they cannot represent actual REDUCTION of CARBON in the body! Those processes also affect VERY small amounts of the carbon, not enough to seriously even need to think about when considering amounts of bodyfat!

By the way, you might see the connection here between when you do serious exercise and then have to breathe heavily for a while? In doing strenuous exercise, you DO use up some bodyfat molecules (but a disappointingly small amount of them. We will shortly see in the Technical paragraph below that even when we exercise hard enough where our breath is TWICE normal, that only removes the carbon from around 1/1100 pound of bodyfat per minute. A full hour of such strenuous exercise and we can remove only around 1/20 pound of bodyfat!). Due to the requirements of the exercise, the body naturally accesses some of your energy supplies, first, the sugars, which are most easily accessed fast, but then the bodyfat stores. As those (sugar or) lipid or triglyceride molecules are oxidized, carbon dioxide molecules are formed, which get carried to the lungs and then exhaled with the next outgoing breath. If you do TWICE as much exertion, then twice as much of the lipid or triglyceride (bodyfat) molecules get oxidized, and twice as much exhaled breath is needed to carry all that carbon away from the body! Now you know! (You also breathe more heavily to get more oxygen INTO the body, to be able to do all that oxidization of all that carbon into carbon dioxide. The body has an immense number of unique chemical reactions, and we have greatly simplified the matter here!)

This brief discussion is intended to show you that virtually ALL the carbon that can leave your body must leave by your exhaled breath, and that all the impressive claims of flashy advertising which claim otherwise are simply not credible. IF some program causes you to BREATHE MORE HEAVILY, either deeper breathing or faster breathing or both, THAT WILL directly increase your body's ability to get rid of undesired bodyfat. So the next time you see any of those ads on TV or elsewhere, THINK about whether they are describing any credible way where your breathing is increased. If not, there is no realistic reason to spend money to buy what they are promoting!

On a more technical level, each INCOMING breath draws in air which is at the natural 0.038% of carbon dioxide, and each outgoing breath contains around a maximum of 4.4% of carbon dioxide. When sitting, we breathe around 12 times per minute and each normal breath is around 0.5 liter of air. This all means that in each minute of normal breathing, we exhale around 0.25 liter of carbon dioxide. This means that each minute, we each exhale around 0.5 gram of carbon dioxide, or around 1/1000 of a pound. (In an entire year of normal breathing, we each exhale around 500 pounds of carbon dioxide!) This includes around 1/3500 pound of actual carbon atoms per minute. If they had come from normal foods (averaging 40% carbon atoms), that represents around 1/1400 pound of food which would disappear during that minute (of normal breathing). At around 2200 Calories per pound of average normal food, that means that around 1.6 Calories of food (or other energy sources) gets used up every minute.

If the carbon atoms had come from lipid or triglycerides bodyfat molecules instead, a far more concentrated source of stored energy, only around 1/2200 pound of bodyfat would need to get used up during that minute (of normal breathing). This situation would occur if the person went on a fast without eating any food, or if the person exerted himself more than could be supported by the food recently eaten. At 3500 Calories per pound of bodyfat, that again means that around 1.6 Calories of bodyfat would get used up every minute. Since a day includes 1440 minutes, that again would account for the 2,200 Calories of energy that our metabolism needs to use up every day to keep us alive. This then proves that each minute of regular breathing involves exhaling the carbon atoms from the equivalent of either 1/1400 pound of average food or 1/2200 pound of bodyfat. That is essentially the ONLY significant process the body has of removing carbon from itself, which it does in order to supply energy for its many processes!

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In order to actually lose bodyfat, one must accomplish TWO separate things. First, the body must speed up its metabolism in some manner, which causes the carbon atoms to be oxidized at a faster rate (along with all the more desirable reasons that occurs in the body, such as maintaining consciousness!) But second is that the body's rate or depth of breathing MUST increase, in order that that larger quantity of oxidized carbon (that is, carbon dioxide) can be expelled from the body in exhaled breath.

ANY claim that does not accomplish both of these, cannot possibly succeed at losing bodyfat.

It is to be noted that certain chemicals such as Cocaine or speeders (amphetamines), tend to cause both of those effects, and so people who are addicted to such drugs tend to lose weight.

A Possible Cause for the Obesity Epidemic!

An interesting field of investigation seems to need research. Is there any chance that obese people might breathe slightly less deeply or slightly slower than average people do? There does not appear to have ever been any research done regarding such questions! Consider the possibility that a person ate a normal-sized diet (2,200 Calories) but for some reason breathed 10% less deeply than an average person might. That difference would be minor enough where it might never be noticed. But because the concentration of carbon dioxide in the exhaled breath is limited by Dalton's Law to around 4.4%, that 10% smaller amount of exhaled air would seem capable of only carrying away 10% less carbon dioxide from the body. The body might therefore easily adapt by simply reducing its metabolism by 10%, in order not to overwhelm the lungs. Doesn't this seem like a possible scenario where the body was intaking 2200 Calories of food but the body was finding it necessary to only use up 1980 Calories each day through metabolism? This would result in that body having an excess of 220 Calories of food intake every day which was not ever used up! The body would naturally convert it into triglycerides and then store it in bodyfat. Every 16 days, that body would therefore add one more pound of bodyfat, possibly without the person having any clue why that was happening!

If this is true, is there any way to reverse it? Only research could determine that. But it certainly seems an attractive thought to consider trying to TEACH obese people to start to breathe a little more deeply! Whether or not their metabolism would then stay with its existing rate or whether it might increase by that 10% that the body USED TO NEED seems an interesting question!

It might be very useful if it turned out that simply teaching obese people to breathe slightly more deeply might contribute toward their solving their obesity problem!

There seems to be an additional possible effect. If one breathes shallowly, then the exhaled breath, which only has around 2/3 the oxygen in it, does not be ejected very far from the nose. This might increase the percentage of exhaled air that gets re-inhaled. That could slightly reduce the amount of oxygen taken into the lungs, which therefore provides less oxygen for bodily processes, specifically including the process described above which removes carbon atoms from the body. So this secondary effect might INCREASE the deletorius effects of smaller scale breathing even more regarding getting rid of carbon atoms and therefore excess bodyfat.

This presentation was first placed on the Internet in January 2009.

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C Johnson, Theoretical Physicist, Physics Degree from Univ of Chicago