Re: How does perspiration make you lose fat?

How does perspiration make you lose fat?
 
Well this is a good question. There are various ways to answer this
question depending on why on is perspiring. For example, one perspires when
one is sitting still in a real hot room without excising. One could also be
sitting in a room that is not hot but your very nervous. Lets say that 5
people drew a number out of a hat and one of you will be selected for a
full university scholarship along with a new car and trip around the world.
So you know your chances are good at winning (1/5 or 20% likely to be
selected). You sit in your chair but you are real nervous. This can make
you perspire as well even though the room is not hot and your not
exercising. You can also think about when your excising and you are
perspiring. In this case you are mostly trying to loose heat from your body
from the heat generated by contracting skeletal muscles. The heat lose is
helped by sweating and when air passes over the wet skin heat is carried
away from the body. This is called evaporative cooling. 

So depending on the cause of the perspiration the answer to your question
can vary. If your running and sweating one will burn fuels for the body
which could be fat reserves, but it is not that perspiration itself is
causing the fat to be broken down. In the various causes mentioned above
the mechanisms that cause one to perspire can also cause one to burn up
fat. The general answer your looking for probably centers around this
concept. Nervousness, exercise as well as sweating in a hot room without
exercising are all controlled by the nervous system  referred to the
autonomic nervous system. 	The autonomic nervous system (ANS)  is divided
into sympathetic, parasympathetic, and “metasympathetic” (intrinsic) parts.
Together, they innervate the blood vessels, heart, smooth muscles, viscera
and glands. The sympathetic and parasympathetic systems, which are derived
from different parts of the central nervous system (CNS), often exert
antagonistic effects on their common targets. The autonomic system
functions primarily as a modulator of the vital processes inside the
organism. It is obvious that, without such coordination, adaptive behavior
for an animal would be impossible. 

The sympathetic nervous system in the one that is active when you get
scared and gives you goose bumps on your skin. This system also helps you
to sweat. The sympathetic response also causes the release of a hormone
from your body called adrenaline (also called epinephrine). This compound
circulates in your blood helping your heart to speed up and cause fat cells
to start breaking down lipids (fat) so that the fat can be turned into
energy for cells to use. Also lipid  in other tissues like muscle is
stimulated to be broken down. I cut and pasted a reference from a medical
journal related to this topic. I realize the article is very technical but
it does allow you to see what researchers do in relations to the type of 
question you are asking.

	In summary, as far as I know perspiration does not make you lose fat but
the actions within your body that make you perspire also make you lose fat. 

All the best,
Robin
>>>>>>>>>>>
ARTICLE #1
Am J Physiol. 1998 Aug;275(2 Pt 1):E300-9. 	
Effects of epinephrine on lipid metabolism in resting skeletal muscle.

Peters SJ, Dyck DJ, Bonen A, Spriet LL.

Department of Human Biology and Nutritional Sciences, University of Guelph,
Guelph, Ontario N1G 2W1, Canada.

The effects of physiological (0, 0.1, 2.5, and 10 nM) and pharmacological
(200 nM) epinephrine concentrations on resting skeletal muscle lipid
metabolism were investigated with the use of incubated rat epitrochlearis
(EPT), flexor digitorum brevis (FDB), and soleus (SOL) muscles. Muscles
were chosen to reflect a range of oxidative capacities: SOL > EPT > FDB.
The muscles were pulsed with [1-14C]palmitate and chased with
[9,10-3H]palmitate. Incorporation and loss of the labeled palmitate from
the triacylglycerol pool (as well as mono- and diacylglycerol,
phospholipid, and fatty acid pools) permitted the simultaneous estimation
of lipid hydrolysis and synthesis. Endogenous and exogenous fat oxidation
was quantified by 14CO2 and 3H2O production, respectively. Triacylglycerol
breakdown was elevated above control at all epinephrine concentrations in
the oxidative SOL muscle, at 2.5 and 200 nM (at 10 nM, P = 0.066) in the
FDB, and only at 200 nM epinephrine in the EPT. Epinephrine stimulated
glycogen breakdown in the EPT at all concentrations but only at 10 and 200
nM in the FDB and had no effect in the SOL. We further characterized muscle
lipid hydrolysis potential and measured total hormone-sensitive lipase
content by Western blotting (SOL > FDB > EPT). This study demonstrated that
physiological levels of epinephrine cause measurable increases in
triacylglycerol hydrolysis at rest in oxidative but not in glycolytic
muscle, with no change in the rate of lipid synthesis or oxidation.
Furthermore, epinephrine caused differential stimulation of carbohydrate
and fat metabolism in glycolytic vs. oxidative muscle. Epinephrine
preferentially stimulated glycogen breakdown over triacylglycerol
hydrolysis in the glycolytic EPT muscle. Conversely, in the oxidative SOL
muscle, epinephrine caused an increase in endogenous lipid hydrolysis over
glycogen breakdown.


ARTICLE #2
Ann Nutr Metab. 1991;35(2):89-97. 	

Effect of changes of water and electrolytes on the validity of conventional
methods of measuring fat-free mass.

Brodie DA, Eston RG, Coxon AY, Kreitzman SN, Stockdale HR, Howard AN.

Department of Movement Science and Physical Education, University of
Liverpool, UK.

Fat-free mass was measured by hydrodensitometry, electrical impedance and
total body potassium before and after water and electrolyte loss induced by
(a) the administration of the diuretic frusemide, and (b) sweat loss. All
methods of measuring fat-free mass were shown by pilot experiments to have
procedural reliability. The diuretic caused a reduction in apparent
fat-free mass of 2.63 kg by the impedance method, of 2.33 kg by
hydrodensitometry and of 1.8 kg by total body potassium. Water and
electrolyte loss from sweating caused a fat-free loss of 2.3 kg, 2.7 kg and
1.3 kg by the same three procedures. Urinary potassium accounted for about
one fifth of the observed 40K fat-free mass loss. Each method was thus
clearly sensitive to the induced water loss. These data suggest that in
evaluating the composition of weight loss, existing methods of measuring
body composition do not distinguish between water and other more critical
components of fat-free mass. It is thus essential that stable hydration
levels are established for any longitudinal comparison of weight loss by
these methods.


ARTICLE #3
J Sports Med Phys Fitness. 2002 Mar;42(1):38-44. 	
The influence of transient change of total body water on relative body fats
based on three bioelectrical impedance analyses methods. Comparison between
before and after exercise with sweat loss, and after drinking.

Demura S, Yamaji S, Goshi F, Nagasawa Y.

Faculty of Education, Kanazawa University, Japan. demura@ed.kanazawa-u.ac.jp

BACKGROUND: The purpose of this study was to clarify the influence of
change of total body water caused by exercise and drinking, on relative
body fat (%BF) based on three bioelectrical impedance analyses (BIA)
methods, between hand and foot (H-F), between hand and hand (H-H), and
between foot and foot (F-F). METHODS: The subjects were 30 Japanese healthy
young adults aged 18 to 23 years (15 males, 15 females). Measurements were
made three times for each BIA method; before and after exercise with sweat,
and after drinking, and also twice according to the under water weighing
(UW) method, before exercise and after drinking. A pedaling exercise, with
a bicycle ergometer, was used for 60 minutes as the exercise. RESULTS: The
relationship of %BF between the UW method and each BIA method was mid-range
or more (r=0.765-0.839). However, %BF based on the H-F and F-F BIA methods
were higher than that based on the UW method. After drinking, %BF of all
the BIA methods were higher than the UW method. %BF of the BIA methods
after exercise indicated values lower than those before exercise. %BF of
the H-F and H-H BIA methods after drinking were a little higher than those
before exercise, indicating that those measurements reflect a slight change
of body water. CONCLUSIONS: It was demonstrated that %BF of any BIA method
reflect the change of body water caused by exercise, sweating, and drinking.