A technical question about overweight people...

[302efi]

The human body stores "energy" fat cells and it gains weight. When you use you muscles you use energy which in turn causes you to lose fat cell that you have stored, correct ?...

Ok then, for the most part, why is it that overweight people get so tired after such little "work"? Their body has a larger amount of spare energy then non-overweight people so which in turn should allow then to do more work over a longer period of time ?

Is it that the human muscles get "over worked" because of the extra weight they have to move ? ..but if that was the case, then since they have so much extra stored "energy" on their bodies, their muscles should have more then enough fuel to keep going ??

 

[PsharkJF]

It's not because your body can't handle the stress you're putting on it, it's just your muscles are not used to the exertion and tire easily.

Lift weights for 2 months and I guarantee you you will end up not being sore at all after about the second week.

Edit: Also, people who do not do regular excerise use their energy less effeciently than others, iirc.

 

[gamefreakgcb]

Originally posted by: PsharkJF
It's not because your body can't handle the stress you're putting on it, it's just your muscles are not used to the exertion and tire easily.

Lift weights for 2 months and I guarantee you you will end up not being sore at all after about the second week.

Edit: Also, people who do not do regular excerise use their energy less effeciently than others, iirc.

Yup. The more time you spend the more your muscles learn to use energy efficiently and get better and better at whatever you do regularly, in this case excercise.

 

[302efi]

Originally posted by: PsharkJF

Edit: Also, people who do not do regular excerise use their energy less effeciently than others, iirc.

Good point guys

 

[Matthias99]

I agree with previous posters about overall muscular efficiency, and that you have to work harder to move a heavier body. Reduced cardiovascular fitness is also a factor.

Furthermore, on a biochemical level, it's a lot harder to convert fat and protein to energy than loose carbohydrates in food. An overweight person would live longer without food before starving to death (since they have more stored calories to burn off in place of ingested food), but it doesn't make them able to exercise longer -- you can't get at the energy quickly enough for it to make a difference.

 

[302efi]

...an overweight person would live longer without food before starving to death (since they have more stored calories to burn off in place of ingested food)...

I guess I was applying that to my first post...more stored energy = more work that could be done

..I didnt take into consideration that the fat cells would somewhere provide a different source of energy vs. ingested food

 

[Rongisnom]

It's also interesting to note that if you are overweight and go on a massive diet your body will actually start chewing into what little muscle that you have instead of the fat. At first your body is afraid that you are encountering a famine and so it tries to stock up on as much stored energy as possible.

Ain't life a bitch!

 

[BustaBust]

It requires more energy for overweight people to move about and their bodies
probably aren't used to it either.

I will not get into the biology data, but this is what it is basicly.

 

[rezinn]

Matthias said it right. You can only store so much glucose and glycogen in your body, and once it's used up different energy sources (protein, fatty acid oxidation) can be used, but require more time to mobilize. So they are basically energy stores whereas carbohydrates are useful for energy immediately. So yeah, fat people can live a longer time if they are starving, but they can't really get more energy from their fat to use for work.

 

[sundev]

Originally posted by: 302efi
The human body stores "energy" fat cells and it gains weight. When you use you muscles you use energy which in turn causes you to lose fat cell that you have stored, correct ?...

No, muscles used already stored energy (glycogen) to get energy when the muscles are put to work, they don't use up the fat cells. Fat takes too long to convert to energy, so it's not a good fuel source when you need immediate energy.

Rather, like others have said, the purpose of fat is so the body has a backup energy source when food becomes low (but only after tons of muscle has already been catabolized!) That's why if you go on a crazy diet where you don't eat much, you will lose a lot of weight, but it will at first be mostly water and muscle, and only then will fat come off.. and consequently you will be much weaker (i.e. it's not possible to go on a diet and come out shredded - ever see anorexics?).

 

[Peter]

Marathon runner says: Fat metabolism is slow, and doesn't provide enough energy to fuel the exercise in its entirety. You need to rev up at a slow to medium steady pace for at least half an hour before you burn a mentionable amount of fat at all. Then you sustain the exercise for as long as you can, limited by when your carbohydrate storage runs out.
(The art of running a marathon is to scale your pace such that your carb storage runs out exactly when you cross the finish line.)

Fat people (no euphemisms here, thank you) have several problems that tire them early. One is, obviously, unsuitable nutrition, carb storage never well plentished. You can't drive a race with the fuel on empty. Secondly, you always have to shift your own weight around on top of the actual exercise. Thirdly and probably most importantly, unfit people don't have the efficience in oxygen transport through lungs and blood to provide for a mentionable energy throughput.

btw, it's not like you need to use up your carbs before the body attacks the fat. That's a common and easy misconception, in fact all of the low-carb craze and bullsh*t stems from. In reality, whenever there is a certain stretch of physical activity, the fat metabolism revs up, and the body tries to stretch its carb supplies by burning fat alongside with it, up to around 50 to 60 percent of the ongoing energy requirement - when fully revved up, which takes about an hour, and only if there is plenty of oxygen in the blood. When oxygen runs low, carb burnage is preferred, because its per-oxygen-molecule energy output is higher.

Your body ain't stupid. Learn to use its capabilities.

 

[302efi]

Damn I'm glad I asked this question...You guys really know alot about the human bodys energy storage and usage methods...whoever said use computer guys are computer nerds

 

[Gibsons]

Just two points

Someone who is overweight does indeed have more energy stored up, but it's not going to come into use under any near-normal activity. The quote you'll sometimes hear is that a person of average build has enough energy stored as fat to run two marathons. It's kind of like asking since a fuel truck has more energy stored in it than a Porsche, why isn't the fuel truck faster? It's only faster after the Porsche runs out of gas.

Secondly, you don't necessarily burn the fat *cells*, you burn the fat molecules stored inside the cells. The fat cell ramains, it's just no longer filled with lipids. Apparently these cells have some proclivity to re-acquire a full store a fat and this is thought (in part at least) to be the reason people end up "yo-yo dieting."

 

[Peter]

The energy stored as fat, in a normal person, is enough for a sustained coast-to-coast run Forrest Gump stylee. (I'm exaggerating!)
Let's say you've got 15 percent body fat, which is lean for a man and unhealthily so for a woman, at 75 kilos, then that's 66000 calories of energy there (roughly, rounded for ease of further calculation).

Assuming an (optimistic) 60:40 fat:carb energy mix during sustained running, how far would that take you?
Well, given that the human body doesn't ever store more than about 2200 kcals worth of glycogen, you'd get to burn of 3300 kcals of fat before your blood sugar drops to rock bottom and the exercise is over - 1/20th of your fat storage.
Now let's say we want to run marathons, and since it is proven that one can run a marathon without running out of carbs, you're good for about two or three weeks of daily marathon running before you'll run out of fat. And you're going to have to stuff yourself with pasta to the max every evening so you'll be refuelled the next day.

If you're trying a sustained in-one-go stunt though, you'll have to throttle yourself to a carb usage of roughly 250 kcals per hour, because that's about as much as you can replentish through digestion while exercising. With an energy budget of roughly 600 kcals per hour total, you're not going to run very fast, but you will definitely be on the move ... and it'll take almost 200 hours of that before you've worked your 11 kilos of fat off. While you've been stuffing yourself with 50000 kcals worth of carbohydrates to even be able to keep going.

Yes, all those "ten minutes a day for an athlete's body, no diet" homeshopping miracles are LYING. In your face.

Fact of life: If you want to lose fat, you need to do two things:

(1) Move your arse.
(2) Improve your nutrition. Not "lower", mind, "improve". Less fat, more carbs (to be able to exercise at all).

 

[PlasmaBomb]

Originally posted by: Gibsons

Secondly, you don't necessarily burn the fat *cells*, you burn the fat molecules stored inside the cells. The fat cell ramains, it's just no longer filled with lipids. Apparently these cells have some proclivity to re-acquire a full store a fat and this is thought (in part at least) to be the reason people end up "yo-yo dieting."

Quite right the body only burns the fat from the cells. You are infact born with fat cells (adipose tissue) in your body (white fat). Most of these are empty (some specialist fat cells are used to help keep you warm as a baby by rapidly burning fat to generate heat- brown fat unfortunately adults have practically no brown fat). Normal adipose tissue is capable of holding a great deal of fat (up to about 85% of the cell can be fat). How full these cells actually are, depends on exercise, lifestyle, diet etc. The problem is that your body is capable of converting excess energy (amino acids, glucose or triglycerides) into fat and then storing it in these fat cells. For example too much sugar in you diet: Excess glucose gets converted to fat in the liver and then stored in (mainly) adipose tissue. (I say mainly because some fat is stored in the liver and muscles too!). This is why you need to eat healthily rather than just eating low fat (the body needs some dietary fat to function normally).

During a diet the amount of energy available to your body is decreased so it makes use of energy stores. When you lose weight (after muscle and water loss) what happens is that the average fat content of the adipose tissue is reduced (the number of adipose cells remains fairly constant).

It should also be noted that it is possible to reverse the the process of energy conversion- fat can be broken down to produce glucose via a process called gluconeogenesis. This would need to be taken into account in other examples.

 

[Gibsons]

It should also be noted that it is possible to reverse the the process of energy conversion- fat can be broken down to produce glucose via a process called gluconeogenesis. This would need to be taken into account in other examples.

I think you're thinking about protein, not fat. Only small portions of a fat molecule can be converted to glucose.

 

[Peter]

PlasmaBomb, recent findings have been that the human (!) body does practically NOT use the sugar-to-fat path (de novo lipogenesis). Most lab animals do, hence the misconception. Mass surveys of tens of thousands of people have shown (e.g. in Scotland) that it isn't the sugarmunchers who are fat, it's the fat overeaters.

Simple sugars do however lead to zero fat usage as long as the blood sugar is raised (from the sugar intake). So the combination of simple sugars and fats is what makes you get fat the fastest. Yes, that's donuts and sweet coffee, burger and coke, etc. etc.

Also, excess protein is not converted to fat. In a huge effort, this is eventually disposed of through the kidneys and urine. Atkins diet is not good for your blood vessels and kidneys, folks. (Again, recent studies showed it's just the protein overkill that makes it "work", not the low carbs or anyting else.)

 

[PlasmaBomb]

Originally posted by: Peter
PlasmaBomb, recent findings have been that the human (!) body does practically NOT use the sugar-to-fat path (de novo lipogenesis). Most lab animals do, hence the misconception. Mass surveys of tens of thousands of people have shown (e.g. in Scotland) that it isn't the sugarmunchers who are fat, it's the fat overeaters.

Simple sugars do however lead to zero fat usage as long as the blood sugar is raised (from the sugar intake). So the combination of simple sugars and fats is what makes you get fat the fastest. Yes, that's donuts and sweet coffee, burger and coke, etc. etc.

Also, excess protein is not converted to fat. In a huge effort, this is eventually disposed of through the kidneys and urine. Atkins diet is not good for your blood vessels and kidneys, folks. (Again, recent studies showed it's just the protein overkill that makes it "work", not the low carbs or anyting else.)

Ok so protein and fat can be converted into glucose in some animals (it's not very efficient though). I haven't come across the study do you have a link/ref? I would be interested to read it. I remember reading an article about the protein overload inhibiting the mechanisms which make you hungry. I agree that it isn't good for your blood vessels.

 

[bswjrny]

Did someone forget to mention the physics of the issue? That basically, the bigger and heavier any living thing is, the less it can do (or move) in relation to its mass. That's why an ant can lift 40x its own body weight and humans not much more than 1x (and why Tyrannasaurus Rex's legs were half its body mass, took that much just to keep him standing).

On another tangent, most depictions of super-human strength in movies, comics, etc., never really get the physics right. Basically, any "superpunch" launching a normal human 20 feet into the air - the power needed to generate that force would pulverize him. On the other hand, the puncher would have to be sufficiently anchored to keep himself from flying back in recoil.

But all that real-world stuff dissapears when you're watching "The Incredibles." See it.

 

[Peter]

PlasmaBomb, one main contributor to the topic of sugar and carbs is one Dr. Acheson - googling yields lots of results and debate. Interesting read, really. Then there's been BBC studies and surveys done in Scotland (whose inhabitants are a yielding test group, for their rapid growth (pun not intended) in massively overweight people as well as for a hair-raising sugar consumption). The surprise in the statistics there was that the sugar/carb overeaters are actually slimmer, statistically relevantly so, than the average Scotsman, while a strong correlation has been found between fat content in the nutrition and body fat.

Then there's other misc results like that Austrian university professor who made his students eat as much rice and pasta as they possibly could for weeks, monitoring their weight. Statistically relevant weight gain was not found. Another experiment conducted on in-bed patients showed that fat synthesization doesn't kick in until you overfeed carbs to around 150% of your actual daily requirements.

German researchers (funded by Kellogg's, incidentally) found the same connection between food preference (in terms of fat content) and body fat in children, and also had evidence of a non-connection between carb intake and body fat. Northern Europe looked at inheritance factors, and found that there is one - surprise again: It isn't any metabolistic factors you inherit, it's the food preferences. Surprise No. 2: You actually inherit that from your genetic parents, not the parents who raise the child. (Study conducted on foster children, to separate exactly those factors.)

Interesting stuff, plenty of it on the web, if you want to dig into it. What it all boils down to is what I already said: If you don't want to get fat, stay away from fat. Revving up your metabolism helps keep the balance and/or lose weight.

News headline:

OBESITY STUDY IN SEARCH OF LARGER TEST GROUP

 

[dkozloski]

I live in Fairbanks, Alaska. I found that if I moderated food intake to about 1000 calories /day and exercised heavily i.e. walked 10 miles plus per day through ankle deep snow going as hard as I could go while carrying a fifty pound pack with the ambient temp in the -40 to-50deg.F range I could easily lose a pound to a pound and a half every day. I felt better as I went along and I reached my weight loss goal of about 60 lbs. easily. How does the energy burn to maintain body temp factor in with energy burn to produce work?

 

[bobsmith1492]

Most of your energy used goes to metabolism (i.e. generating heat). According to one calcuation, my body uses almost 2000 calories a day just by sitting here breathing.

On the converse side, why is it no matter how much food I eat (or don't eat) I am stuck at this same weight (160)??

 

[Gibsons]

How does the energy burn to maintain body temp factor in with energy burn to produce work?

Shivering burns a few calories for sure, there are probably other things as well. Been a while since I read up on this...

There's also "brown fat" which sort of works like a car stuck in neutral, the motor (mitochondria in this case) runs at a high rate producing a lot of heat, but doing no "work." Humans don't have a lot of it though; IIRC just a couple of patches around the shoulder blades IIRC. There are drugs that can have this effect on all mitochondria and thus burn a lot of calories, but there's some danger associated with them.

On the converse side, why is it no matter how much food I eat (or don't eat) I am stuck at this same weight (160)??

I've been the same way most of my life (145 though)... getting older tends to cure it though, but not in the preferred way.

 

[NewBlackDak]

Originally posted by: dkozloski
I live in Fairbanks, Alaska. I found that if I moderated food intake to about 1000 calories /day and exercised heavily i.e. walked 10 miles plus per day through ankle deep snow going as hard as I could go while carrying a fifty pound pack with the ambient temp in the -40 to-50deg.F range I could easily lose a pound to a pound and a half every day. I felt better as I went along and I reached my weight loss goal of about 60 lbs. easily. How does the energy burn to maintain body temp factor in with energy burn to produce work?

I always wondered how accurate those calculations are.
I weigh 235lbs. I do heavy weight bearing exercies(free weights) 3 days a week, and 2 hours of full-court basketball on two more. The wife and I usually ride bikes or play doubles raquetball on Saturday. According to the last one I saw it takes ~3800 calories just to maintain my wieght if I say I'm very active. If I say extremely active it says ~4500.
No wonder out grocery bil lis so high!!

 

[Peter]

dkoslozki, you'd be losing weight even faster if you ate more carbs and exercised harder. The saying goes "the carb fire burns the fat"

Baseline consumption for average weight males indeed is about 2000 kcal, more if you weigh more, particularly if that extra weight is muscle.

Back in the days when I was actively pursuing competition swimming, during heavy exercise weeks we used to inhale upward of 8000 kcal per day and still lose weight. Four hours of intense swimming plus some time in the gym and a bit of running each day takes its toll ... in fact some of us had to limit their exercising simply because they didn't manage to eat enough.