# Swimming increases appetite ?



## djk80 (Aug 28, 2008)

I have been doing a mix of swimming, running and biking.

However I did read somewhere that swimming increases appetite?
I actually do kind of notice I am pretty hungry after swimming as well....

Can anyone confirm or have any reasoning?

Thanks


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## Built (Aug 28, 2008)

I think it has something to do with how cold the body gets - you have to fight to warm it up, and that needs food. 

This article said a few interesting things that kinda make sense, too: The truth about swimming and weight loss...


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## djk80 (Aug 28, 2008)

Thanks thats an awesome article


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## bigsahm21 (Aug 28, 2008)

Also notice in the Olympics that many swimmers (with the exception of Phelps, who pretty much defies all logic) aren't ripped up at all.  Some of them are a little chubby, actually.  I've heard that over time, swimmers' bodies naturally want to gain more body fat so they can become more buoyant; don't know if that's true or not but I think it would make sense.


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## VanessaNicole (Sep 4, 2008)

djk80 said:


> I have been doing a mix of swimming, running and biking.
> 
> However I did read somewhere that swimming increases appetite?
> I actually do kind of notice I am pretty hungry after swimming as well....
> ...



It does.

It's an effect of parasympathetic nervous system stimulation resulting from exposure to the cold water.

Like a very mild form of the Mammalian dive Reflex.

This is why I always dicourage my obese patients from choosing swimming as their primary for of exercise.


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## VanessaNicole (Sep 4, 2008)

bigsahm21 said:


> Also notice in the Olympics that many swimmers (with the exception of Phelps, who pretty much defies all logic) aren't ripped up at all.  Some of them are a little chubby, actually.  I've heard that over time, swimmers' bodies naturally want to gain more body fat so they can become more buoyant; don't know if that's true or not but I think it would make sense.



This is not true at all.


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## Biggly (Sep 4, 2008)

One issue to consider is that the body actually burns more calories while trying to keep warm, so one would expect the cold swimmers to eat more afterwards.

However I fully agree that swimming has been shown to increase appetite, probably more than actually burnt.


B.


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## VanessaNicole (Sep 4, 2008)

Biggly said:


> One issue to consider is that the body actually burns more calories while trying to keep warm, so one would expect the cold swimmers to eat more afterwards.
> 
> However I fully agree that swimming has been shown to increase appetite, probably more than actually burnt.
> 
> ...



This is totally untrue.

Submersion in cold water causes stimulation of the parasympathetic nervous system which causes the body to use energy more conservatively. The body shunts blood towards the vital organs at the center of the body and constricts peripheral blood vessels in order to save heat.

Basically, the body compensates for the cold water by holding on to it's heat and reducing it's metabolism. 

It most certainly does not burn more calories to stay warm.

They've done this study thousands of times with a bathtub and cold water.


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## Built (Sep 4, 2008)

Oooh, interesting! Thanks for that Vanessa. 

Got a link to a study - I'd love to read that and keep it for my files.


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## Biggly (Sep 5, 2008)

maybe with extreme cold yes but mild cold makes the body seek means of heating up; what do you think shivering is?



B.


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## hoka81 (Sep 5, 2008)

Sure swimming is the best for good appetite


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## VanessaNicole (Sep 10, 2008)

Biggly said:


> maybe with extreme cold yes but mild cold makes the body seek means of heating up; what do you think shivering is?
> 
> 
> 
> B.



Shivering is a muscle spasm designed to generate heat. It is, however, accompanied by what are called compensational changes in blood flow, blood pressure, cardiac output and total energy usage.

It does not increase caloric expediture at all.

Besides that, shivering usually last for about 15 minutes and is then followed by further shunting which further reduces energy usage.

The body seeks to conserve energy in all times of stress. It's called homeostasis.


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## Biggly (Sep 11, 2008)

Homeostasis is something I'm familiar with but the idea of generating heat without calories is a new one to me?

A "calorie" is actually a unit of heat energy.

From Wiki:

"Shivering is a bodily function in response to early hypothermia in warm-blooded animals. When the core body temperature drops, the shivering reflex is triggered. Muscle groups around the vital organs begin to shake in small movements in an attempt to create warmth by expending energy. Shivering can also be a response to a fever as a person may feel cold, though their core temperature is already elevated.

Located in the dorsomedial portion of the hypothalamus near the wall of the third ventricle is an area called the primary motor center for shivering. This area is normally inhibited by signals from the heat center in the anterior hypothalamic-preoptic area but is excited by cold signals from the skin and spinal cord. Therefore, this center becomes activated when the body temperature falls even a fraction of a degree below a critical temperature level.

Increased muscular activity results in wasted heat - here the heat is utilized for warmth."

Now Wiki is by no means authorative but that is indeed the usual definition of shivering, deliberate burning of energy, ie calories, to produce heat. 

But you say the body, having deliberately burnt some energy for heat, compensates by not burning energy elsewhere?

Rather than digging into that issue specifically, I think the important word here is not homeostasis, which is just the body seeking balance, but the other word - "stress".

If the body is stressed to the point where it will deliberately burn energy just for heat, then compensate for that by denying parts of itself their normal energy levels, however you look at it, you have a body with an energy shortage.

Most forms of exercise can actually dampen your appetite for awhile. Indeed a heavy session in the gym can leave you feeling like throwing up let alone facing a large meal - but the munchies you get after slimming are not like that. Be it due to a different mechanism, perhaps considered more of an emergency, whatever, fact is a lot of peeps are peckish after a swim but not after a gym.

Yes you should have a post workout meal anyway but the studies I've seen show peeps eat considerably more after swimming than after other forms of exercise. 

Most forms of exercise you're trying to cool down after, with swimming you come out with the shivers and are trying to _warm up_. To me it makes sense and studies do seem to confirm it - you end up eating more calories than you burnt from the exercise of swimming.

Yes your body may compensate - but then _you _compensate by _eating _more than you normally would.



B.


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## Ben dur (Sep 11, 2008)

a calorie
is by definition

the amount of energy require to heat one liter of water 1 degree C


this is by recollection, no source there
but just by definition, it would be suggested that the cold water would require the body to burn calories to maintain heat...

in extreme cold this may be counterbalanced by the bodies effort to maintain balance, but in a 80degree pool, i doubt the body will be shutting down, and im sure the body is burning energy to stay warm




then again... this is what my logic tells me, and i havnt even read the study linked above....


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## Biggly (Sep 11, 2008)

Yep, the above makes sense and I agree with the logic - the point is that studies suggest people eat MORE as a result, compared to their calorie intake after normal exercise, leading to a calorie surplus rather than the expected calorie deficit of exercise.

It's counter-intuitive but studies point to it, my own experience is that I'm ravenous after swimming, and it does makes sense if your body has been deliberately wasting calories that it would trigger a "you're starving, eat!" response.



A.


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## Ben dur (Sep 11, 2008)

agreed


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## VanessaNicole (Sep 11, 2008)

You can get into symantics all you want, but the fact remains that being subjected to the cold does not cause one to expend more total calories.


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## Ben dur (Sep 11, 2008)

its not so much a discussion of semantics

rather at what tempeture is the body expending the maximum amount of calories

you argue that in cold water the body is shutting down
but what if is were to swim in say
the gulf of mexico, just 16 miles from my house
in september the water temperature is easily 90degrees?

surely my body will be struggling to cool rather than shutting down in an attempt to fend off hypothermia

now say a pool where the temp could easily be 80
would this be cool enough to cause a shutdown? or neutral enough not to have any effect?


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## bigsahm21 (Sep 11, 2008)

i hear also that swimming burns more calories than pretty much any other aerobic exercise.  of course it depends on the intensity, but i've read that a "moderate" swim burns more calories than a "moderate" jog would.


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## P-funk (Sep 11, 2008)

"Involuntary heat production by shivering is the primary means of increasing heat production during exposure to cold.  Maximal shivering can increase the body's heat production by approximately five times the resting value.  In addition, release of thyroxine from the thyroid gland can also increase metabolic rate.  Thyroxine acts by increasing the metabolic rate of all cells in the body.  Finally, an increase in blood levels of catecholamines (epinephrine and norepinephrine) can cause an increase in the rate of cellular metabolism.  The increase in heat prodction due to the combined influences of thyroxine and catecholamines is called non shivering thermogenesis."

Powers SK, Howley ET.  *Exercise Physiology: Theory and Application to Fitness and Performance.*  McGraw Hill. 6th Ed. pg 244. 2007


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## seems (Oct 6, 2008)

Same logic works for this as you eat more in winter. When you are in water your body is cold and you need more energy to fight it so your appetite will increase.


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## min0 lee (Oct 6, 2008)

Any activity makes me hungry.


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## Built (Oct 6, 2008)

seems said:


> Same logic works for this as you eat more in winter. When you are in water your body is cold and you need more energy to fight it so your appetite will increase.



Don't the animals usually eat less in winter? 
Shorter days = more melatonin. 
Melatonin in the presence of insulin upregulates leptin. Result: less hunger.

Thoughts?


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## Biggly (Oct 6, 2008)

They tend to eat less in winter as there's less food..

Other critturs eat a heap _before _winter to develop insulation and reserves, ie fat.


B.


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## Built (Oct 6, 2008)

Indeed. Longer days, more time to east, less melatonin to upregulate leptin. Works out well for hybernation.


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