http://en.wikipedia.org/wiki/Metabolic_water
http://en.wikipedia.org/wiki/Water_metabolism
Fluid
balance is the concept of human homeostasis that the amount of fluid lost from the body is equal to the amount of fluid taken in. Euvolemia is
the state of normal body fluid volume. Water is necessary for all life on
Earth. Humans can survive for 4–6 weeks without food, but for only a few days
without water.
The amount
of water varies with the individual, as it depends on the condition of the
subject, the amount of physical exercise, and on the environmental temperature
and humidity.[1] In the US, the reference daily intake (RDI) for water is 3.7 litres per day (l/day) for human males older
than 18, and 2.7 l/day for human females older than 18[2] including water contained in food, beverages, and drinking water. The
common misconception that everyone should drink two litres (68 ounces, or about
eight 8-oz glasses) of water per day is not supported by scientific research.
Various reviews of all the scientific literature on the topic performed in 2002
and 2008 could not find any solid scientific evidence that recommended drinking
eight glasses of water per day.[3][4][5] For example, people in hotter climates will require greater water
intake than those in cooler climates. An individual's thirst provides a better
guide for how much water they require rather than a specific, fixed number. A
more flexible guideline is that a normal person should urinate 4 times per day,
and the urine should be a light yellow color.
A constant
supply is needed to replenish the fluids lost through normal physiological
activities, such as respiration, perspiration and urination. Food contributes 0.5 to 1 l/day, and the metabolism of protein, fat, and carbohydrates produces another 0.25 to 0.4 l/day,[6] which means that 2 to 3 l/day of water for men and 1 to 2 l/day of
water for women should be taken in as fluid, i.e. drunk, in order to meet the
Recommended Daily Intake (RDI). In terms of mineral nutrients intake, it is
unclear what the drinking water contribution is. However, inorganic minerals generally enter
surface water and ground water via storm
water runoff or through the Earth's crust. Treatment processes also lead to the
presence of some minerals. Examples include calcium, zinc, manganese,phosphate, fluoride and sodium compounds.[7] Water generated from the biochemical metabolism of nutrients provides a significant proportion of the daily water
requirements for some arthropods and desert animals, but provides only a small fraction of a human's necessary
intake. There are a variety of trace elements present in virtually all potable
water, some of which play a role in metabolism. For example sodium, potassium and chloride are common chemicals found in small quantities in most waters, and
these elements play a role (not necessarily major) in body metabolism. Other
elements such as fluoride, while beneficial in low concentrations, can cause
dental problems and other issues when present at high levels. Water is
essential for the growth and maintenance of our bodies, as it is involved in a
number of biological processes.
Profuse
sweating can increase the need for electrolyte (salt) replacement. Water intoxication (which results in hyponatremia), the process of consuming too much water too quickly, can be fatal.
The human kidneys will normally adjust to varying levels of water intake. The kidneys
will require time to adjust to the new water intake level. This can cause
someone who drinks a lot of water to become dehydrated more easily than someone who routinely drinks less.
Fluid can leave
the body in many ways. Fluid can enter the body as preformed water, ingested food and drink and to a lesser extent as metabolic water which is produced as a
by-product of aerobic respiration (cellular respiration) and dehydration
synthesis.[8]
A constant
supply is needed to replenish the fluids lost through normal physiological
activities, such as respiration, sweating and urination. Water generated from thebiochemical metabolism of nutrients provides a significant proportion of the daily water
requirements for some arthropods and desert animals, but provides only a small fraction of a human's necessary
intake.
In the
normal resting state, input of water through ingested fluids is approximately
1200 ml/day, from ingested foods 1000 ml/day and from aerobic respiration 300 ml/day, totaling
2500 ml/day.[9]
Input of
water is regulated mainly through ingested fluids, which, in turn, depends on thirst. An insufficiency of water results in an increased osmolarity in the extracellular fluid. This is sensed by osmoreceptors in the organum vasculosum of the lamina
terminalis, which trigger thirst. Thirst
can to some degree be voluntarily resisted, as during fluid restriction.
·
The majority of fluid output
occurs via the urine, approximately 1500 ml/day (approx 1.59 qt/day) in the normal adult
resting state.[9][10]
·
Some fluid is lost through perspiration (part of the body's temperature control mechanism) and as water vapor
in expired air. These are termed "insensible fluid losses" as they cannot be
easily measured. Some sources say insensible losses account for 500 to 650
ml/day (0.5 to 0.6 qt.) of water in adults,[9][11] while other sources put the minimum value at 800 ml (0.8 qt.).[12] In children, one calculation used for insensible fluid loss is
400ml/m2 body surface area.
·
For females, an additional 50
ml/day is lost through vaginal secretions.
The body's homeostatic control mechanisms, which maintain a constant internal environment,
ensure that a balance between fluid gain and fluid loss is maintained. The
hormones ADH (Anti-diuretic Hormone, also
known as vasopressin) and Aldosterone play a major role in this.
·
If the body is becoming fluid-deficient,
there will be an increase in the secretion of these hormones, causing fluid to
be retained by the kidneys and urine output to be reduced.
·
Conversely, if fluid levels
are excessive, secretion of these hormones is suppressed, resulting
in less retention of fluid by the kidneys and a subsequent increase in the volume
of urine produced.
If the body
is becoming fluid-deficient, this will be sensed by osmoreceptors in the organum vasculosum of lamina
terminalis and subfornical organ.[14] These areas project to the supraoptic nucleus and paraventricular nucleus, which contain neurons that secrete the antidiuretic hormone, vasopressin,
from their nerve endings in the posterior pituitary. Thus, there will be an
increase in the secretion of antidiuretic hormone, causing fluid to be retained
by the kidneys and urine output to be reduced.
A
fluid-insufficiency causes a decreased perfusion of the juxtaglomerular
apparatus in the kidneys. This activates the renin-angiotensin system. Among
other actions, it causes renal tubules (i.e. the distal convoluted tubules and
the cortical collecting ducts) to reabsorb more sodium and water from the
urine. Potassium is secreted into the tubule in exchange for the sodium, which
is reabsorbed. The activated renin-angiotensin system stimulates zona
glomerulosa of the adrenal cortex which in turn secretes hormone aldosterone.
This hormone stimulates the reabsorption of sodium ions from distal tubules and
collecting ducts. Water in the tubular lumen cannot follow the sodium
reabsorption osmotically, as this part of the kidney is impermeable to water;
release of ADH (vasopressin) is required to increase expression of aquaporin
channels in the cortical collecting duct, allowing reabsorption of water.
Effects of
illness
When a
person is ill, fluid may also be lost through vomiting, diarrhea, and hemorrhage. An individual is at an increased risk of dehydration in these instances,
as the kidneys will find it more difficult to match fluid loss by reducing
urine output (the kidneys must produce at least some urine in order to excrete
metabolic waste.)
Fluid balance
in an acute hospital setting
In an acute
hospital setting, fluid balance is monitored carefully. This provides
information on the patient's state of hydration, renal function and
cardiovascular function.
·
If fluid loss is greater than
fluid gain (for example if the patient vomits and has diarrhoea), the patient
is said to be in negative fluid balance. In this case, fluid is
often givenintravenously to compensate for the loss.
·
On the other hand, a positive
fluid balance (where fluid gain is greater than fluid loss) might
suggest a problem with either the renal or cardiovascular system.
If blood
pressure is low (hypotension), the filtration rate in the kidneys will lessen, causing less fluid reabsorption and thus less urine
output.
An accurate
measure of fluid balance is therefore an important diagnostic tool, and allows
for prompt intervention to correct the imbalance.
There are a
variety of trace elements present in virtually all potable water, some of which
play a role in metabolism; for example sodium, potassium and chloride are common chemicals found in very small amounts in most waters, and
these elements play a major role in body metabolism. Water is essential for the
growth and maintenance of our bodies, as it is involved in a number of
biological processes.
See also
References
1. Jump up^ Maton,
Anthea bj; Jean Hopkins, Charles William McLaughlin, Susan Johnson, Maryanna
Quon Warner, David LaHart, Jill D. Wright (1993). Human Biology and
Health. Englewood Cliffs, New Jersey, USA: Prentice Hall. ISBN 0-13-981176-1.
4. Jump up^ H.
Valtin, Drink at least eight
glasses of water a day." Really? Is there scientific evidence for "8
× 8"? Am J Physiol Regul
Integr Comp Physiol 283: R993-R1004, 2002.
5. Jump up^ Negoianu,
Dan; Goldfarb, Stanley (2008). "Just add
water" (PDF). J. Am.
Soc. Nephrol 19 (6): 1041–1043. doi:10.1681/ASN.2008030274. PMID 18385417.
7. Jump up^ World Health
Organization (WHO). Geneva,
Switzerland. Joyce Morrissey Donohue, Charles O. Abernathy, Peter Lassovszky,
George Hallberg. "The contribution
of drinking-water to total dietary intakes of selected trace mineral nutrients
in the United States." Draft, August 2004.
8. Jump up^ Saladin,
Kenneth S. Water, Electrolyte, and Acid-Base Balance (New York: McGraw-Hill
Companies, Inc., 2010), 943-944.
9. ^ Jump up to:a b c d e Walter F., PhD. Boron (2005). Medical Physiology: A Cellular
And Molecular Approaoch. Elsevier/Saunders. ISBN 1-4160-2328-3. Page
829
14. Jump up^ M.J.
McKinley and A.K. Johnson (2004). "The
Physiological Regulation of Thirst and Fluid Intake". News in Physiological Sciences 19 (1): 1–6. doi:10.1152/nips.01470.2003.PMID 14739394.
Retrieved 2006-06-02.
Metabolic water
From Wikipedia, the free encyclopedia
Metabolic water refers to water created inside a
living organism through their metabolism, by oxidizing energy-containing substances in
their food. Metabolism produces about 110 grams of water per 100 grams of fat,[1] 41.3 grams of water per 100g of protein and 55 grams of water per 100g of starch.[2][3]
Some organisms, especially xerocoles, animals living in the desert, rely exclusively on metabolic water. Migratory birds must
rely exclusively on metabolic water production while making non-stop flights.[4][5] Humans, by contrast, obtain
only about 8-10% of their water needs through metabolic water production.[6]
In mammals, the water produced from metabolism of
protein roughly equals the amount needed to excrete the urea which
is a byproduct of the metabolism of protein.[6] Birds, however, excrete uric acid and can have a net gain of
water from the metabolism of protein.
5. Jump up^ Klaassen M (1996). "Metabolic constraints on long-distance migration in
birds". J Exp Biol 199 (Pt 1):
57–64. PMID 9317335.
6. ^ Jump up to:a b Board on Agriculture and
Natural Resources (BANR), Nutrient Requirements of Nonhuman Primates:
Second Revised Edition (2003), p. 144. [1]
Drinking Water Increases Fat Oxidation
I am sure you have heard or read the weight loss tip of drinking water to help you lose weight. Well, for most of us the reason for drinking water was to help feel fuller faster so we ate less calories.
Also, if we drank water instead of caloric beverages we would consume less calories, which may lead to weight loss. There were also the critics that may have told you this was ridiculous and you were wasting your time drinking water as a tool for greater weight loss.
Well, there is some pretty solid evidence that says this is not ridiculous at all and the studies conducted on this have been some of the more rigorous studies conducted with crossover experiments and randomized and controlled trials.
In various crossover experiments drinking water resulted in lower total caloric intake with the subjects that were tested. The reason for this is simple and it is because they were not consuming calorie filled beverages. They were replacing these caloric beverages with water that has zero calories.
What was also found was that the individuals do not eat less food when they know they are drinking caloric beverages. They still eat the same amount of calories regardless of if their beverages contained calories or not.
Drinking Water Increases Fat Oxidation
Fat oxidation is at its greatest when your insulin levels are low. The reason for this is because insulin inhibits or decreases the ability of rate limiting enzymes that breakdown triglyceride fats into free fatty acids. As well as the transport of these free fatty acids into the mitochondria and Krebs cycle to be burned for energy. Since water does not contain calories or carbohydrates like over beverages it does not trigger an insulin response. If you were to compare it to the glycemic index water is of course 0, milk is around 35, juice is around 50 and sugary drinks are as high as 80.
Keeping your insulin levels lows results in greater rates of fat oxidation. Now remember this doesn't apply just to water. The foods you eat and what combination of nutrients you eat can all influence the insulin response. Keeping your insulin response consistently lower throughout the day will allow your body to burn more stored fat as energy.
Anytime your insulin and blood sugar levels are elevated you stop fat breakdown and fat oxidation.
There have been decades of crossover studies that consistently show higher levels of fat oxidation when drinking water compared to caloric drinks before or during low to moderate exercise. If you look at the average of these studies the fat oxidation is around 40% greater after water is consumed than after a caloric beverage.
It is normal for fat oxidation to be depressed for a length of time after a meal because naturally your body is going to release insulin to properly utilize the nutrients you just consumed. What you choose for your beverage though can dictate how long that slow down of fat oxidation really is.
Research has shown that drinking water instead of a caloric beverage can restore the rate of fat oxidation to pre-meal levels about 2 hours sooner than if you were to drink a caloric beverage with the same meal.
Some studies have shown that consumption of 500-600 calories from carbohydrates can depress fat oxidation for 6 hours after consumption.
Hypocaloric Diets and Water Leads To Weight Loss
Two very interesting intervention studies looked at a hypocaloric diet and then the same diet plus water as the beverage. One study looked at 48 randomized overweight or obese men and women. They were given a hypocaloric diet plus 500ml of water at each meal or they were just given the hypocaloric diet (control) with no water.
The results showed that weight loss in the water group was 2kg greater. In analysis of data from the Stanford A to Z Study they focused on 155 overweight premenopausal women who reported drinking less than 1L/ day of water before beginning 1 of 4 different weight programs. The programs were the Atkins diet, Zone diet, LEARN diet, and Ornish diet. The 4 programs do recommend drinking 1L/day of water or more and limiting or no intake at all of caloric beverages.
After 2 months of their diet classes they all reported higher water intake and less caloric beverage intake. Independent of any changes in diet or physical activity those who increased their water intake and decreased caloric beverage intake had significantly greater weight loss.
Summary
Ok, lets summarize all this data as some of it may have gotten confusing.
Drinking water during the day and at your meals instead of drinking calorie filled beverages decreases your total calorie intake and it also promotes greater fat oxidation, which is the burning of stored fat as energy.
So drink water at meals and in-between meals instead of calorie filled beverages. Take your Prograde Metabolism so you are consuming scientifically proven nutrients that boost your metabolism and help to control blood sugar and insulin levels. Finally, eat a higher protein rich and lower carb diet to minimize the insulin spikes that will depress fat oxidation for hours after that meal.
There have been decades of crossover studies that consistently show higher levels of fat oxidation when drinking water compared to caloric drinks before or during low to moderate exercise. If you look at the average of these studies the fat oxidation is around 40% greater after water is consumed than after a caloric beverage.
It is normal for fat oxidation to be depressed for a length of time after a meal because naturally your body is going to release insulin to properly utilize the nutrients you just consumed. What you choose for your beverage though can dictate how long that slow down of fat oxidation really is.
Research has shown that drinking water instead of a caloric beverage can restore the rate of fat oxidation to pre-meal levels about 2 hours sooner than if you were to drink a caloric beverage with the same meal.
Some studies have shown that consumption of 500-600 calories from carbohydrates can depress fat oxidation for 6 hours after consumption.
Hypocaloric Diets and Water Leads To Weight Loss
Two very interesting intervention studies looked at a hypocaloric diet and then the same diet plus water as the beverage. One study looked at 48 randomized overweight or obese men and women. They were given a hypocaloric diet plus 500ml of water at each meal or they were just given the hypocaloric diet (control) with no water.
The results showed that weight loss in the water group was 2kg greater. In analysis of data from the Stanford A to Z Study they focused on 155 overweight premenopausal women who reported drinking less than 1L/ day of water before beginning 1 of 4 different weight programs. The programs were the Atkins diet, Zone diet, LEARN diet, and Ornish diet. The 4 programs do recommend drinking 1L/day of water or more and limiting or no intake at all of caloric beverages.
After 2 months of their diet classes they all reported higher water intake and less caloric beverage intake. Independent of any changes in diet or physical activity those who increased their water intake and decreased caloric beverage intake had significantly greater weight loss.
Summary
Ok, lets summarize all this data as some of it may have gotten confusing.
Drinking water during the day and at your meals instead of drinking calorie filled beverages decreases your total calorie intake and it also promotes greater fat oxidation, which is the burning of stored fat as energy.
So drink water at meals and in-between meals instead of calorie filled beverages. Take your Prograde Metabolism so you are consuming scientifically proven nutrients that boost your metabolism and help to control blood sugar and insulin levels. Finally, eat a higher protein rich and lower carb diet to minimize the insulin spikes that will depress fat oxidation for hours after that meal.
References:
Almiron-roig E, Drewnowski A. Hunger, thirst and energy intakes following consumption of caloric beverages. Physiol Behav. 2003;79:767-773.
Beridot-Therond ME, Arts I, Fantino M, DeLaGueronniere V. Short-term effects of the flavour of drinks on ingestive behaviours in man. Appetite. 1998;31:67-81.
Canty DJ, Chan MM. Effects of consumption of caloric vs noncaloric sweet drinks on indices of hunger and food consumption in normal adults. Am J Clin Nutr. 1991;53:1159-1164.
Cecil JE, Palmer CNA, Wrieden W, et al. Energy intakes of children after preloads: adjustment, not compensation. Am J Clin Nutr. 2005;82:302-308.
Della Valle DM, Roe LS, Rolls BJ. Does the consumption of caloric and non-caloric beverages with a meal affect energy intake? Appetite. 2005;44:187-193.
Flood JE, Roe LS, Rolls BJ. The effect of increased beverage portion size on energy intake at a meal. J Am Diet Assoc. 2006;106:1984-1990.
Hagg A, Jacobson T, Nordlund G, Rossner S. Effects of milk or water on lunch intake in preschool children. Appetite. 1998;31:83-92.
King NA, Appleton K, Rogers PJ, Blundell JE. Effects of sweetness and energy in drinks on food intake following exercise. Physiol Behav. 1999;66:375-379.
Paterson CR. Essentials of Human Biochemistry. Edinburgh: Churchill Livingstone; 1987.
Nutritional Biochemistry and Metabolism. New York: Elsevier; 1991.
Foster-Powell K, Holt SHA, Brand-Miller JC. International table of glycemic index and glycemic load values: 2002. Am J Clin Nutr. 2002;76:5-56.
Kirwan JP, O'Gorman DJ, Cyr-Campbell D, Campbell WW, Yarasheski KE, Evans WJ. Effects of a moderate glycemic meal on exercise duration and substrate utilization. Med Sci Sports Exerc. 2001;33:1517-1523.
Kirwan JP, O'Gorman D, Evans WJ. A moderate glycemic meal before endurance exercise can enhance performance. J Appl Physiol. 1998;84:53-59.
Wallis GA, Dawson R, Achten J, Webber J, Jeukendrup A. Metabolic response to carbohydrate ingestion during exercise in males and females. Am J Physiol Endocrinol Metab. 2006;290:E708-E715.
Stookey JD. Drinking water results in greater fat oxidation than beverages that contain carbohydrate during low to moderate intensity exercise. Poster presented at Experimental Biology, New Orleans, April 18-22, 2009.
Febbraio MA, Chiu A, Angus DJ, Arkinstall MJ, Hawley JA. Effects of carbohydrate ingestion before and during exercise on glucose kinetics and performance. J Appl Physiol. 2000;89:2220-2226.
Ostman EM, Elmstahl HGML, Bjorck IME. Inconsistency between glycemic and insulinemic responses to regular and fermented milk products. Am J Clin Nutr. 2001;74:96-100.
Montain SJ, Hopper MK, Coggan AR, Coyle E. Exercise metabolism at different time intervals after a meal. J Appl Physiol. 1991;70:882-888.
Dennis EA, Dengo AL, Comber DL, et al. Water consumption increases weight loss during a hypocaloric diet intervention in middle aged and older adults. Obesity. 2010;18:300-307.
Stookey JD, Constant F, Popkin BM, Gardner C. Drinking water is associated with weight loss in overweight dieting women independent of diet and activity. Obesity (Silver Spring, Md). 2008;16:2481-2488.
Nutrition Today "Drinking Water and Weight Management" November/December 2010 Volume 45 Number 6S
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