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Tankgirl
Distinguished Member
| Joined: | 1 Jul 2011 |
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| Posts: | 538 |
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Posted: 20 Jul 2011 08:05 pm |
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There's been a long-running debate that for someone to be over a normal weight they must be eating more than 2000 calories a day. If What Brad Pillion is saying is correct, fat burns far less calories than people may expect.
http://www.youtube.com/watch?v=7qZEbqr3PwM&feature=related
Also make sense why athletes have to eat mind-boggling amounts of calories to feed the muscle they have. Personally I can't decide if that sounds like fun or a chore!
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JSABD
Distinguished Member
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Posted: 20 Jul 2011 09:26 pm |
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Tankgirl wrote: There's been a long-running debate that for someone to be over a normal weight they must be eating more than 2000 calories a day. If What Brad Pillion is saying is correct, fat burns far less calories than people may expect.
http://www.youtube.com/watch?v=7qZEbqr3PwM&feature=related
Also make sense why athletes have to eat mind-boggling amounts of calories to feed the muscle they have. Personally I can't decide if that sounds like fun or a chore!
This guy is 100% WRONG! I bet he thinks the earth is flat.
His false assumption is that the BMR is staying the same when in reality BMR increases as weight increases. It increases because it has to
Please do not believe this guy's opinion. It is not a fact.
The heavier a person is the more body mass they have. One thing that the moron who made the video forgot is that humans are warm blooded. The maintain a body temperature of 98.6F. Look at it this way. You have a big house and a small house. You keep the temperature of each house at 76 F one house is 1000 square feet and the other is 2000 sq/ft. Which house is going to require more heating oil?
Let's talk work. You have two identical trucks. One is towing a trailer and the other is not. Which burns more fuel?
Take the fit person vs the unfit person. Both weigh 200 lbs. Both ascend a flight of stairs. Who burns more energy?
Now they are at rest. The fit 200 pound man has a resting heart beat of 60 bpm and a shallow respiration rate of 15 and he was low/normal blood pressure. The unfit 200 pounder has a heart rate of 120. respiratory rate of 30 deeper breaths and high blood pressure. Who is using more energy/calories?
The guy in the video is talking out of his butt. What he is saying does not have even a shred of validity.
A 160 pound man burns about 100 calories as hour. A 320 pound man burns about 200 an hour. It's called the laws of physics... more specifically the conservation of mass ansd yes it applies to humans. If you argue with Issac Newton you lose.
http://mb-soft.com/public3/weight.html
Virtually everyone who claims to tell you truth regarding weight loss either lies to you or is ignorant of basic facts to tell you! Science is based on some absolute Laws of Science, including two which are important here, the Conservation of Energy and the Conservation of Mass (weight). One pound of human bodyfat is actually atoms which had been eaten and drunk, which get rearranged into enormous molecules with very strong chemical bonds between the atoms. Large amounts of food energy is therefore required to first create all those chemical bonds in that pound of bodyfat. At whatever point the pound of bodyfat gets used up, it MUST release all that energy! AS bodyfat, it is very complex molecules of mostly carbon, hydrogen and oxygen atoms, with around 78% of them being carbon. That is very similar to the benefits of fossil fuels which are also mostly carbon, such that relatively small space is needed for rather large amounts of stored (available) energy.
WHEN that pound of bodyfat is used up, the laws of science INSIST that (1) VERY LARGE amounts of energy must be released (the chemical binding energies); and (2) all the atoms from those molecules MUST go somewhere! It turns out that the hydrogen and oxygen atoms are pretty easy to dispose of, as water in sweat, exhaled breath, urination, etc. But the body ONLY has ONE METHOD of disposing of virtually all carbon atoms, and the excellent energy density of bodyfat means that that means about 78% of all the weight of atoms which need to be disposed of. Companies which promote diets, pills, powders, liquids that claim to cause miraculous loss of bodyfat NEVER address those two Laws of Science! IF they actually have some process where even ONE pound of bodyfat is to disappear, you should insist that they explain WHERE the 3,600 Calories of energy (an enormous amount of heat energy or exercise energy) goes to, BECAUSE IT MUST GO SOMEWHERE! Also, how and where that 13 ounces of carbon atoms must go to, again BECAUSE THEY MUST GO SOMEWHERE!
So when salespeople sound really convincing with whatever they are selling, please first note that they never even MENTION these two basic laws of science which they MUST obey! There is every indication that they are not even aware of the actual scientific facts!
If anyone is interested in the HARD SCIENCE click here ---> http://mb-soft.com/public3/weight.html
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Nir
Senior Administrator
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Posted: 21 Jul 2011 05:08 am |
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on Calories Per Hour, however, we have long believed in personalising the calculation which is why a BMR/RMR calculator is made available - click 'Calories Burned Calculator' at the top of the page.
Additionally, the ACSM recommends that women eat no less than 1200 calories and men eat no less than 1800.
The 2000 calorie figure is bogus.
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JSABD
Distinguished Member
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Posted: 21 Jul 2011 07:19 pm |
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Sitting Quietly Sitting quietly, without any other activity such as reading, speaking or writing, burns about 84 calories per hour, based on a body weight of 150 pounds. Watching television, meditating, and listening to music are activities typically included in sitting quietly.
Sitting and Reading While sitting and reading quietly, an average person burns slightly more calories than while sitting quietly, at a total of about 88 calories per hour. Difficult reading, in which the person must concentrate intensely, will burn a few more calories per hour than simple reading since brain activity actually burns calories.
Sitting and Working on a Computer Working on a computer while sitting burns about 102 calories per hour, depending on the intensity of the work. If other activity such as shuffling files, filing while sitting, or moving around to answer phones is included, up to 170 calories can be burned per hour.
Sitting and Talking on the Phone Talking on the phone while sitting burns the same number of calories as working on a computer, with an average of 102 calories per hour burned. Gesturing, raising your voice or getting excited can increase the calories burned to about 120 per hour.
Sitting and Eating Though it seems funny, calories are burned when you eat. A person sitting and eating burns about 130 calories per hour, or the equivalent of half of a candy bar.
http://www.nutristrategy.com/activitylist3.htm
http://www.mayoclinic.com/health/exercise/SM00109
http://mb-soft.com/public2/humaneff.html
I think this is why some people claim I am an engineer.
For convective heat losses, we are going to simplify by assuming that there is no wind. Therefore we can use formulas for Natural Convection. A very simplified version gives h = 0.2 * (T1 - T2)1/3; for our situation above, h = 3.42. The convective heat loss is then that number times the surface area (of 20 sf) times the temp difference (5?é??F) or 340 Btu/hr. (around 85 Calories per hour) If a person were naked, this would apply, but the effect of clothing tends to insulate some parts of the body, particularly the very important torso, and we are going to suggest here that the effect of clothing will generally reduce this CONVECTIVE heat loss to around 70 Calories/hour. This value depends tremendously on the type and amount of clothing worn.
The third method that the body discards heat is by exhaled breath. In normal breathing, we generally exhale about 0.5 liter of air about twelve times every minute. This is therefore around 6 liters of air per minute. This air is at our core body temperature, of 98.6?é??F temperature, air that had been inhaled a few seconds earlier at room temperature. If the room is at 68?é??F that means the room air had been raised in temperature (by the body) by around 30?é??F. The 6 liters of air/minute is 360 liters/hour or about 13 cubic feet per hour which has a weight of around 1 pound of air per hour. Air has a thermal capacity of around 0.24 Btu/lb/?é??F. In raising 1 pound of air by 30?é??F, that means that the amount of heat added to the air (from inside our body) is (30 * 1 *.24) or around 7 Btu/hr of EXHALED heat in the (dry) air.
There is also water vapor in the exhaled breath. As the air is inside the lungs, the relative humidity there quickly rises to 100%. (This is actually IMPORTANT to the body in getting rid of a lot of the roughly one pound of water that is produced as a waste product of the body's basal metabolism each day, the other waste product than carbon dioxide.) Therefore, water along the walls of the lungs evaporates into the air to be exhaled. This is additional heat energy that gets carried away. Using standard analysis, the partial pressure of the saturated water vapor at 98.6?é??F is around 0.9 PSI. This defines the (weight) proportion of the water vapor and the dry air to be around one to 27. We will not go through all the math here but it is pretty simple to determine how much weight of water vapor is exhaled per hour. Most of the energy is involved in evaporating the water into water vapor, but then it also has to be warmed from the inhaled breath air temperature up to the 98.6?é??F that gets exhaled. Evaporating sufficient water at room temperature and then raising it to 98.6?é??F for the 6 liters of air represents around 1/25 pound of water per hour being evaporated and heated, or around 40 Btu/hr. (The heat of vaporization of water is around 1,000 Btu/pound).
Between these two components of the exhaled breath, we have around 47 Btu/hr or 12 Calories/hr lost due to EXHALED BREATH. We must remember that this was based on a 68?é??F room, and standard (waking, sedentary) rates of breathing and depth of breathing. For example, during sleep, the respiration rate generally slows down and becomes more shallow, so those heat losses become less, while during heavy exercise or exertion, respiration becomes faster and often deeper, so that greater heat losses in the breath occur then.
This then gives a daytime resting total of around (26 + 70 + 12) or around a ballpark estimate of 110 Calories per hour of heat energy sent away from the body. During the night, the heat loss is generally somewhat lessened. As a ballpark number we could consider a day of losing 110 Calories for 16 hours, or 1760 Calories per day as being credible. During our eight hours of sleep, it has been scientifically confirmed that we normally lose around 80 Calories per hour, so we have a 24-hour day total of around 110 * 16 + 80 * 8 or 2400 Calories, a number that is in reasonable agreement with the accepted value of food energy consumption for a sedentary adult individual.
Notice that ALL of these numbers are extremely dependent on the clothing we have on and also the temperature of the room we are in. We keep saying ballpark for these reasons. Our point here is simply to show the logic and the math by which this data can be processed, such that any reader might then do a more precise analysis based on specific clothing and room temperature!
(The body also has the capability of dumping quite a lot of heat by sweating, where the evaporation of the water removes heat from the room air very close to the skin, and therefore increases the [local] temperature differentials we discussed above. [This is why your skin feels cooler when you sweat.] This then allows the body to dump substantial amounts of heat when the body is in danger of overheating. In a sedentary situation, the body creates a very small amount of sweat, and we have been ignoring that energy loss here.) Remembering that a pound of water (or sweat) involves around 1,000 Btus (or 250 Calories) for its evaporation, you probably see why Marathon runners need to grab so much water along the race, in order to replace water lost through sweating. Due to all the exertion of such a race, the body is generating so much heat energy, partly due to actual physical work done but far more due to the many chemical reactions that must occur in the accelerated metabolism, that a large amount of heat must be released from the body. Rather than the body letting the skin temperature rise to 120?é??F or more in order to release that much energy by radiation and convection, it chooses to sweat to release a lot of the energy. It is quite an amazing system!
This then accounts for a ballpark of 2,200 or 2,400 Calories of input energy, (for relatively sedentary existence) in rough agreement with what dieticians say.
We might note that we are examining all this from a Physics perspective, where Energy can never be either created or destroyed. When we refer to a human taking in an amount of energy equal to 2,200 Calories (for metabolic activities) it might first seem that the metabolic activities therefore "use up" all that energy and that there should be no balance of energy. But if we examine the WHOLE picture, where all the metabolic activities are able to complete, THEY also eventually result in degrading all the energy into heat. This discussion is therefore correct in accounting for exactly as many Calories or Btus of energy IN and OUT. There are only a few exceptions to this. During the GROWTH of a child, additional structures are created, and so energy in IS greater than energy out. Similarly, when a person gains or loses weight (body fat) an imbalance occurs, since one pound of human bodyfat has the energy content of around 3,500 or 3,600 Calories.
This analysis does not include the "productive" work output. When the body is more active, the metabolic activity increases, to power all the needed operations inside the body, while also producing productive work output which could be as much as an additional 1/4 of that (as noted above). In what is considered heavy work by ASHRAE, the amount of productive work done can be around 0.15 horsepower, or 96 Kcal/hr or 110 watts. The body has to increase its metabolic rate to accomplish everything necessary, with the net efficiency being around 20%. Therefore, the body is actually then using up around 480 Kcal/hr or 550 watts of total consumed energy. This must all be disposed of by radiation and convection from the skin (therefore bloodflow near the skin is increased so that the skin temperature rises to accomplish this) and the rate and depth of breathing is increased to also dump more heat, and finally, the body sweats to dispose of additional heat.
The numbers above are generally meant to apply to adult men of around 200 pounds weight. Women generally have smaller total surface area and therefore they need to use less energy to maintain their core body temperature, so they tend to need to eat less, and therefore have lower daily dietary intake. But the reasoning is still completely valid.
http://en.wikipedia.org/wiki/Orders_of_m?óÔé¼?ª
Approximate heat production of human body is about 100 watts.
To convert watts to BTU per hour, see:
http://www.infoplease.com/ipa/A0001729.h?óÔé¼?ª
multiply watts by 3.4121
So, about 341 BTU per hour.
Your metabolism would heat 341 pounds of water 1 degree F, in an hour.
Here is a conversion calculator http://www.gordonengland.co.uk/conversion/energy.htm
This is not personal or opinion so show me with numbers and forumlas not harris-benedict put physics how 2000 calories per day can maintain more that 140 pound i a woman of any activity level.
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Tankgirl
Distinguished Member
| Joined: | 1 Jul 2011 |
| Location: | |
| Posts: | 538 |
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Posted: 21 Jul 2011 08:30 pm |
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Purely anecdotal,
Stayed at 2000 calories for a whole month. No weight loss whatsoever.
Dropped to 1700, started losing weight again
So I can either stay at 2000, banging my head against the wall, or drop down to what actually works.
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alisamoran99
Past Member
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Posted: 22 Jul 2011 05:38 am |
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Tankgirl wrote: Purely anecdotal,
Stayed at 2000 calories for a whole month. No weight loss whatsoever.
Dropped to 1700, started losing weight again
So I can either stay at 2000, banging my head against the wall, or drop down to what actually works. This discussion have never ended but some small tips can apply in daily routine,
like walking, cycling, walk while talking on phone or join some sports like football ,cricket etc. it will be help a lot.
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Nir
Senior Administrator
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Posted: 22 Jul 2011 06:24 am |
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I found the article interesting. I can't audit the calculations but I have no reason to suspect the motives or numbers. I do note the "ballpark figure" caveat.
Whether using these rough numbers or using Harris-Benedict or Muffin equations, I urge everyone to use them as starting figures and do your own experiment.
Tom Venuto talks about this in chapter 4 of his book BFFM (add/subtract from intake, increase/decrease exercise etc.)
more anecdotal (though obviously by no means typical) I've been following up a recovering anorexic 20yo 5'5" compulsive exerciser who has gained from 100lb to 148lb whilst eating 1000-1400 calories per day (tracked, using food scale). Cannot stress enough that intake should be tailored to real-world results.
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JSABD
Distinguished Member
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Posted: 22 Jul 2011 10:25 pm |
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When my peeps design an eating plan I don't want them to under eat and that is why they don't go below their BMR. Losing more than 1 pound per 100 pounds per week is never a good idea.
Safety first.
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