# The human body can only process 50g of protein at a time



## CoffeeFiend (Aug 31, 2010)

I heard something to the effect of this a while back, not sure who said it or whether it was somethinng they in turn had just heard. But is it true at all?

Its kind of been stuck in my head and has been one thing influencing trying to get into the habit of eating 6 smaller meals throughout the day (like everyone recommends) over say the usual main 3.

A glass of skimmd milk and a tin of tuna would equal that, that would be damn quick as well considering im busy again.


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## essexboy (Sep 7, 2008)

it will only use what it requires.Any excess, is excessive calories, which is stored as fat.However, every time, I post scientific facts, regarding protein, my threads are deleted.


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## CoffeeFiend (Aug 31, 2010)

essexboy said:


> it will only use what it requires.Any excess, is excessive calories, which is stored as fat.However, every time, I post scientific facts, regarding protein, my threads are deleted.


Thats not cool.. i had a thread deleted the other week too.


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## J55TTC (Nov 2, 2009)

Surely it depends on what type of protein.

If you ingest a blend of whey, caesin etc etc they all break down at different rates so you could have over 50g if this concept is true.


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## CoffeeFiend (Aug 31, 2010)

J55TTC said:


> Surely it depends on what type of protein.
> 
> If you ingest a blend of whey, caesin etc etc they all break down at different rates so you could have over 50g if this concept is true.


Yeah thats a good point


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## Smitch (Dec 29, 2008)

Cue Prodiver.... :whistling:

I suppose there's many different factors involved. Metabolism, body weight etc, but if you stick to 50g 6 times a day you can't go wrong.

Someone said on here recently that they had a protein shake with every meal. If they were having 50g of protein in each meal and a protein shake i suspect a large amount of that protein would be wasted.


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## CoffeeFiend (Aug 31, 2010)

Smitch said:


> Cue Prodiver.... :whistling:
> 
> I suppose there's many different factors involved. Metabolism, body weight etc, but if you stick to 50g 6 times a day you can't go wrong.
> 
> Someone said on here recently that they had a protein shake with every meal. If they were having 50g of protein in each meal and a protein shake i suspect a large amount of that protein would be wasted.


Yeah thats my thinking as well, i want to cram the most i can but not to waste any. I have a stupidly high metabolism anyway but ive been at this so hard i am noticing im actually devloping some fat which is something of a knew concept for me.. >_> nothing crunches cant fix i suppose lol


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## CoffeeFiend (Aug 31, 2010)

Cheers for advice mateys owe you some reps, heading out to campus back later


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## jakelad (Aug 28, 2009)

Iv actually heard it was 32g the body can digest at once. That would make more sense would it? seeing as shakes and bars r all around that


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## Simon m (Apr 3, 2008)

Load of rubbish. The body can process much more than 50g of protein in one sitting. For most of us, it's uncomfortable to eat more than that, but it doesn't mean you cannot or should not do it.


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## defdaz (Nov 11, 2007)

Lol I love how the amount changes as this flies around the net or mouth-to-mouth. Some days it's 30g, some 60g and today it's 50g.

When you eat food it first ends up as a bolus or ball of food in your stomach. This is where the first stage of protein digestion occurs, as the strong acids attack the protein and begin breaking it down into smaller chunks.

The meal isn't then suddenly dumped wholesale into your small intestines and woah if you've broken the 50g limit you're in deep doodoo's buddy! Small amounts of food are let out of the stomach at a rate that depends no the composition of your meal. The major influencing factor is fat content - the more fact in your meal the longer it takes to empty out of the stomach (up to 8 hours). Hence why higher fat meals can make you feel full for longer.

So small amount of protein leave the stomach and are then acted upon in the small intestine to be further broken down into small enough chunks to be absorbed. Once you understand this then it helps you realise that the 50g thing is wrong (as it's not one big meal that has to be quickly acted upon but a whole procession of small amounts of food progressing down the small intestine).

Add to this all the other factors such as protein form - some are already pre-digested to make absorption faster, others take longer to be digested and absorbed due to their properties (i.e. micellular casein) and so on and there's no readily definable upper limit.

You can find your own (highly variable depending on the meal and protein forms!) limit by eating higher amounts until you start to notice increased wind and other gastro-intestinal upsets (like the runs!). Then you'll know you've hit your limit for that moment  .


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## BillC (Jun 11, 2009)

Well it used to be 42g of protein a decade ago. Protein does take a lot for your body to digest and doesn't llike doing it. From what I remember, your pancreas has to work overtime to produce enough protease enzymes to break it down. The reason meal replacement shakes like MetRx were dosed at 40g was because of this. any extra is either stored as fat or most likely just comes out in your poop - protein farts anyone? Myoplex upped the amount to 43g, just to say they had more than MetRx. Now 50g + is commonplace. If there was no limit to how much you could digest in one sitting, might as well stop eating 8 times a day and stick to 3/4 and double up


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## dtlv (Jul 24, 2009)

defdaz said:


> Lol I love how the amount changes as this flies around the net or mouth-to-mouth. Some days it's 30g, some 60g and today it's 50g.
> 
> When you eat food it first ends up as a bolus or ball of food in your stomach. This is where the first stage of protein digestion occurs, as the strong acids attack the protein and begin breaking it down into smaller chunks.
> 
> ...


Good post, and the only thing I'd add to that is that all protein foods (meat, dairy, even veggie proteins) contain a mix of protein fractions that each become available at different rates, making it even harder to give a single one-size-fits-all 'rate of bioavailability' figure.

Unless digestion is impaired, almost all of the protein you ingest will be utlised, although it stands to reason that the more you take in relative to your bodyweight, the higher the percentage of it will be used for deamination and energy rather than for protein turnover or use in metabolic processes.


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## Smitch (Dec 29, 2008)

Ok, so are we saying that preotein shakes are more likely than solid food to not be digested fully then if your body thinks it's had enough?


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## rs007 (May 28, 2007)

Nonsense, categorically.

Your digestive system is a natural buffer. You pack it up with grub, it might take longer, but it will all get processed.

What it does in that processing is another matter.

I also laugh my ass off at how the amount changes every time.

I do believe some protein sources could subvert this buffering system, notably protein concentrates and isolates. Think of them as similar to super processed carbs. THey get through the natural digestivion process WAY faster than our bodies ever evolved to handle. I personally believe it is possible that more of this type of protein, could be excreted, broken down to glucose, whatever.

Also, bone of contention. Define "a sitting". Define "at a time". Like I say, the bodies digestive system includes a natural buffering system. Would be a pretty sh1t system for survival of the organsim quite frankly if it didn't, given that historically, it is only fairly recent we have had easy "on demand" access to food at any time. Stuff just waits in the queue. It has to. The body will deal with it when it gets to it, the only limit is what you can physically ram down your neck without being sick...


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## rs007 (May 28, 2007)

Smitch said:


> Ok, so are we saying that preotein shakes are more likely than solid food to not be digested fully then if your body thinks it's had enough?


My OPINION is that they are more likely to race through the digestive tract as they require far less digestion than solid protien (generally) and might infuse amino acids into the blood stream at a RATE greater than they might be able to be used, for general purposes.

But plenty of guys still get massive on shake heavy diets, so we are heavily into the theoretical here


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## IanStu (Apr 12, 2009)

surely a 20 stone man can use more protein than a 10 stone woman....I dont understand who these figures are based on, its gotta be nonsence as everyone is different!


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## BigStew (May 6, 2008)

Can only digest 30g/40g/50g etc, etc is pure fiction!

Think,

If you go by the 'popular'........6 meals/day & 1.5g protein/lb of body weight........

150lb = 225g = 37.5g/meal

200lb = 300g = 50g/meal

250lb = 375g = 62.5g/meal

There's a vast difference there so who can say definitively, what's right/wrong?

Your body will know & tell you your own limit, (gas, toilet habits, etc).


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## defdaz (Nov 11, 2007)

There seems to be lots of confusion about this.

There's a big difference between protein being digested and absorbed and protein being 'used'.

Almost all of the protein you eat will be digested and absorbed (assuming no gasto-intestinal issues / upsets), within reason. You'll get the farts and worse if you really go nuts (our digestive system is necessarily compromised as we're omnivores). So don't sweat this bit.

How your expensive protein gets used is another story altogether.

Every day your body 'turns-over' many hundreds of grams of protein - far more than you ingest. Amino-acids are broken down and rebuilt over and over again in the body, get used for energy, incorporated into tissue and so on. These processes go on constantly and vary according to the various stresses on the body (i.e. during exercise amino acid use for energy increases). Remember you're not just eating protein to be packed into muscles, it's also used everywhere in your body for myriad functions and energy uses. Getting your body to add more to your muscles is the fun part 

So you have this protein in constant flux in your body and into this pool you add the protein you eat and out of it goes the losses in your urine etc.

So we have=

Daily protein turn-over= protein broken down in body to be used / recycled + ingested protein - protein losses.

This is what your body has to play with. It needs a certain amount to fullfil all its requirements and cover the losses.

For the average normal person the body has normal reached a minimum level of lean body mass that it is happy with, that allows that person to function day to day with few issues. This amount won't change much and so that person is in protein balance (or nitrogen balance as protein is the only nutrient with nitrogen).

For this person protein in will equal protein out and their total protein levels won't change. If that person eats a lot of protein then the body will have no requirements for the extra protein and so it will convert the protein into fat and use it for energy or store it.

For the humble bodybuilder (  ) our over-arching ambition is to increase muscle mass - or be in positive protein (nitrogen) balance every day and so get bigger.

Just eating more protein won't trigger positive nitrogen balance - there has to be a reason for your body to want to increase your muscle mass. Hence why we pound it in the gym.

The body sees that your current muscle mass isn't high enough to deal with the stresses being placed upon it so muscle growth or hypertrophy is triggered.

The point to note about our bodies ability to enlarge its muscles is that it is finite. You only have so much recovery and growth ability - the mechanisms behind it are physical and so can only work at their maximum rate.

Ideally we'd know exactly how much extra protein and energy and nutrients we need to provide our growth machinery for it to do it's job at its maximum rate but this is very difficult (read: impossible) to find out, and would change on a daily basis anyway as any other activity, lack of sleep etc. would all affect your bodies recovery and growth abilities.

All we can do is eat an excess of protein and calories and other nutrients to ensure we aren't limiting our recovery and growth abilities. This is key. Get in more than you need to ensure maximum growth but not so much that you get fat quickly too!

It takes roughly 25% of the energy available in protein for it to be converted to fat whilst carbs are converted without much energy loss at all. This means it takes 3g of protein to make 1g of fat but only just over 2g of carbs to make 1g of fat. So if in doubt consume more protein and limit carbs to minimise fat gain. Sure it's more expensive but you cover both energy and protein requirements nicely.

So,

Protein digestion /absorption - don't worry about it unless you're getting the squits, and

Protein useage - make sure you're eating lots!

Simple! :lol:


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## SK-XO (Aug 6, 2009)

^Good post defdaz, gave you reps.


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## rs007 (May 28, 2007)

Thats a great post defdaz, the protein turnover thing gets ignored by many, but this is how you might need quite a large protein intake, say for sake of argument, 300g per day, but you aren't adding 300g per day of muscle... that would be silly.


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## defdaz (Nov 11, 2007)

Thanks guys. Absolutely mate, wish we could add 300g of muscle a day, day in day out (100kg a year!!!  ). How awesome would that be!


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## dtlv (Jul 24, 2009)

Another great post defdaz... please stop making so much sense so frequently as I can't rep you at the rate you deserve. :lol:

Only thing I'd comment on is excess protein turning into fat... as vicki pollard would say "yeah but no but yeah but no but"...

Excess protein beyond that which is used for the processes you mention gets broken down into three things, ammonia, acetyl coA, and ketoacids.

The ammonia is toxic, and has no real use so gets p!ssed away. The acetyl coA gets used for immediate energy (it isn't an energy substrate itself, but it gets used up in the citric acid cycle which is one of the main process of releasing energy), and the keto acids (which are techincally a form of fat) are intermediate substances that get immediately converted to liver glycogen. If it were mostly converted to glucose then it could potentially be stored as fat, but glycogen doesn't ever convert directly to fat, as it is itself an energy storage medium which only releases its energy on an as-needed basis, with no extra released for conversion to fat.

What's more likely to happen in respect of fat gain on a high calorie/high protein diet is that liver glycogen stores are filled up from converted protein, leaving a higher percentage of carbohydrate and fat with nowhere to go other than conversion to triglycerides and fat storage.

The talk of the metabolic advantage of low carb diets (increased metabolic rate) is often based on the belief that using fat as a prime fuel makes you burn bodyfat at a faster rate... this just isn't true at all, in fact fats as a fuel actually very very slightly reduce metabolic rate compared to carbs. On both high fat/low carb and high carb/low fat diets the same principal dictates fat loss - calories in vs calories out.

The metabolic advantage in low carb eating exists because of the protein, not the fat... as defdaz mentions, there is a much higher energy cost of utlising protein for fuel than any other macro, so without carbs in your diet your body will have to convert a higher amount of the protein to glycogen to fuel the bodies glucose dependent processes and in the process the energy cost to do this will raise your metabolic rate.

Only final bit to say is cautionary... high protein diets are very acidic. Since the blood has to maintain a very narrow pH range, the body has to use buffering mechanisms to a higher degree than in a lower protein diet to compensate for this, and one of the main mechanisms is removing calcium from your bones to buffer the acidity.

Of course the body replaces calcium as it loses, and this may have no ill effect during youth, but it may catch up in old age, as the cells that regulate incorperation of calcium into the bones (osteblasts) only have a limited lifespan, and after about age 60 they are nothing like as functional as before... but a highly acidic diet throughout younger life will use them up much sooner, and lead to much greater risk of osteoporosis. A secondary potential negative related to this bufering mechanism is after the calcium is used to buffer some of the acid, the metabolites of this process need to be flushed vis the kidneys, and these calcium salts are the things that most commonly cause kidney stones.

It all leads me to feel that for health considerations protein intake, just like everythign else, is best kept moderate and the key to making the best from your protein is to select high quality complete proteins and time their usage for when most needed rather than to just eat tons of the stuff everyday.


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## Team1 (Apr 3, 2008)

i just ate 300g of steak. thats a lot of protein. its gonna be digesting and breaking down in my guts for a while....even when my next meal of chicken goes in and that starts breaking down and being used by my body

think about it...total bollocks


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## defdaz (Nov 11, 2007)

Very interesting stuff Dtlv74! Are there many studies looking at the effects of high protein intake and osteoporosis? I would imagine that this is off-set somewhat by the positive affects weight training has on bone density (as long as the individual continues to train)?


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## defdaz (Nov 11, 2007)

Team1 said:


> i just ate 300g of steak. thats a lot of protein. its gonna be digesting and breaking down in my guts for a while....even when my next meal of chicken goes in and that starts breaking down and being used by my body
> 
> think about it...total bollocks


Amen. :thumbup1: And why bodybuilding rocks. 300g of steak. Happy days. :laugh:


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## Team1 (Apr 3, 2008)

yup. ok...things might be different if im knocking back gallons of whey each meal....but....a pile of meat slowly digesting, breaking down, releasing aminos into my blood.....makes you realise thata "sitting" doesnt even fuking exist

****. that steak will still be releasing aminos into my blood at 9pm tonight along with the chicken, and eggs and whatever else.

"sitting" means nothing to your body in terms of solid protein


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## CoffeeFiend (Aug 31, 2010)

Bloody hell pop off for a 2 hour lecture come back and find half the forum discussing in here :laugh: which is pretty good, not read everything yet but can already tell i didnt convey myself properly, as someone said somewhere theres a distinction between protein processed and protein 'used'.


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## dtlv (Jul 24, 2009)

defdaz said:


> Very interesting stuff Dtlv74! Are there many studies looking at the effects of high protein intake and osteoporosis? I would imagine that this is off-set somewhat by the positive affects weight training has on bone density (as long as the individual continues to train)?


There are a few studies that show it, but the focus of those studies is usually the low carb aspect rather than the high protein bit... long term studies on ketogenic diets for epilepsy and other conditions for example show much higher incidences of osteoporosis and even in children, but that is also influenced by the keto aspect which has a stronger acidic effect than the high ratio of protein to carbs.



> * Changes in Bone Turnover in Young Women Consuming Different Levels of Dietary Protein**1*
> 
> * Jane E. Kerstetter, MaryAnn E. Mitnick, Caren M. Gundberg, Donna M. Caseria, Alice F. Ellison, Thomas O. Carpenter and Karl L. Insogna * School of Allied Health, University of Connecticut (J.E.K.)
> 
> ...


This is the one that's probably easier reading though as its a review - http://jn.nutrition.org/cgi/content/full/128/6/1051. Important to note that the acid effect of protein is highly exaggerated when carbs are also low, as carbohydrate foods (the unprocessed ones at least) are the main dietary alkalisers due to the minerals typically found in them, as well as the large amounts of bicarbonate they provide.

I should also, while I'm here, add soemthing to my first post... thinking about it more, there is a bit more of a direct link between high protein intake and fat gain than I suggested, but its kind of specific to a couple of amino acids.

Most amino acids are keto acid forming, but two, alanine and glutamine, are exclusively glucose forming when deaminated in the liver. Unlike the others, these two form glucose which can as we all know end up being converted to fat.

Since many dietary proteins do contain a fair amount of glutamine and alanine (glutamine, leucine and alanine are generally the three dietary aminos we get most of), this can't be ignored.


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## Joshua (Aug 21, 2008)

D - have you thought of any strategies other than high P avoidance, to reduce Ca leaching?

J


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## dtlv (Jul 24, 2009)

Joshua said:


> D - have you thought of any strategies other than high P avoidance, to reduce Ca leaching?
> 
> J


Eat more fruit and veg. Most people don't realise that foods that are acidic in their raw state more times than not are alkaline when it comes to balancing the bodies pH... citrus fruits are all alkaline due to the minerals they contain.

Foods higher in calcium, magnesium, potassium, selenium, sodium and zinc than the acid minerals will alkalize, whilst foods higher in chlorine, iodine, phosphorus and sulphur (the main 'acid' minerals) will acidify.

Most veg has a net alkaline effect because although there's plenty of acid in them, the acids are naturally neutralized during digestion leaving it a simple case alkaline vs acid mineral content to determine the effect of the food on the bodies pH... and all fruit and veg are higher in alkaline minerals than acid ones.

There are the odd exception to fruit being overall alakline... a couple of fruits, cranberries (and one more common one that I've forgotten) have acidic compounds that the stomach cannot neutralize, and so these impart an acidic load that outweighs the alkaline mineralsl they provide.

Grains are acidic due to the protein content, particularly the sulphur aminos, same with beans. Beans also contain a lot of phosphorus in a form which chelates alkaline minerals and tips the balance further towards the acid side. Nuts vary from type to type and I don't remember which is which... google may help. Beyond these groups of veg though, any unprocessed edible plant matter is more likely than not to help keep your pH nicely balanced along side a high protein diet.

If people really can't face a lot of fruit and veg though but do want to alkalize then there is an alternative through supplmentation... greens powders are a good supplement option to go along side a high protein diet, providing a lot of alkaline minerals as well as some beneficial phytonutrients. Failing that, drinking lots of lemon juice in water with celtic or himalayan salts added (not table salt due to the added iodine) will also help alkalize. Sodium bicarbonate drinks also help, although you need to keep them quite dilute to avoid GI issues (more dilute than when bicarb loading).

There's a lot written about akalizing diets that fits the usual pattern of miracle-diet-nonsense, typical to all extreme diet bloggers... claims that such a diet will make you immune to all disease, cure all existing diseases, help you live to a thousand years old and help you win the lottery. A lot of it is taken too far, but in respect of protection against osteoporosis the theory does seem valid and backed up consistently by observation.


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## IronFed (Dec 10, 2008)

Thought this would go nicely with your post Dtlv74:

Alkaline Foods

*Veg*

Asparagus

Artichokes

Cabbage

Lettuce

Onion

Cauliflower

Radish

Swede

Lambs Lettuce

Peas

Courgette

Red Cabbage

Leeks

Watercress

Spinach

Turnip

Chives

Carrot

Green Beans

Beetroot

Garlic

Celery

Grasses (wheat, straw, barley, dog, kamut etc.)

Cucumber

Broccoli

Kale

Brussels Sprouts

*Fruits*

Lemon

Lime

Avocado

Tomato

Grapefruit

Watermelon (is neutral)

Rhubarb

*Drinks*

Fresh vegetable juice

Pure water (distilled or ionised)

Lemon water (pure water + fresh lemon or lime).

Herbal Tea

Vegetable broth

Non-sweetened Soy Milk

Almond Milk

*Seeds, Nuts & Grains*

Almonds

Pumpkin

Sunflower

Sesame

Flax

Buckwheat Groats

Spelt

Lentils

Cumin Seeds

Any sprouted seed

*Fats & Oils*

Flax

Hemp

Avocado

Olive

Evening Primrose

Borage

Coconut Oil

Oil Blends (such as Udo's Choice)

Acidic Foods

*Meats*

Pork

Lamb

Beef

Chicken

Turkey

Crustaceans

Other Seafood (apart from occasional oily fish such as salmon)

*Dairy Products*

Milk

Eggs

Cheese

Cream

Yogurt

Ice Cream

*Others*

Vinegar

White Pasta

White Bread

Wholemeal Bread

Biscuits

Soy Sauce

Tamari

Condiments (Tomato Sauce, Mayonnaise etc.)

Artificial Sweeteners

Honey

*Drinks*

Fizzy Drinks

Coffee

Tea

Beers

Spirits

Fruit Juice

Dairy Smoothies

Milk

Traditional Tea

*Fats & Oils*

Saturated Fats

Hydrogenated Oils

Margarine (worse than Butter)

Corn Oil

Vegetable Oil

Sunflower Oil

*Convenience Foods*

Sweets

Chocolate

Microwave Meals

Tinned Foods

Powdered Soups

Instant Meals

Fast Food

*Fruits*

All fruits aside from those listed in the alkaline foods

*Seeds & Nuts*

Peanuts

Cashew Nuts

Pistachio Nuts


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## CoffeeFiend (Aug 31, 2010)

S_Tezza said:


> Thought this would go nicely with your post Dtlv74:
> 
> Alkaline Foods
> 
> ...


Thats pretty useful, i reckon it should be a sticky thread somewhere


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## DNL (Sep 24, 2010)

not again, please no, no.


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## a.notherguy (Nov 17, 2008)

dont understand that list.

de-ionised water is generally pH 5.4 (ish)

if opened and exposed to air it can absorb CO2 and end up with a pH of 4.5 (ish)

how can that be alkaline?


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## Greyphantom (Oct 23, 2003)

only read page one so far as got to dash... but the reason the amounts change is that it depends on which company is telling you it is only x grams of protein we can use at a sitting... eg one company has 32 grams of protein per serve so it becomes "you can only use 32g protein so we have formulated the perfect amount per serving"... then company y says "well its actully 40g protein and gues what thats exactly what OUR protein supp has in it"... there is no magic number... some can do more some less etc yadda blah...


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## Andrew Jacks (Sep 29, 2010)

Good link here that helps explain the inner workings but states no such answer exists

http://www.uk-muscle.co.uk/food-diet-nutrition-info/30666-interesting-article-protein-absorption.html

Little data exists on the comprehensive metabolic effects of large amounts of dietary protein in the order of 300 to 400 g/d. Intakes of this magnitude would result in some degree of prolonged hyperaminoacidemia, hyperammonemia, hyperinsulinemia, and hyperglucagonemia, and some conversion to fat, but the metabolic and physiological consequences of such states are currently unknown. The upper limit of protein intake is widely debated, with many experts advocating levels up to 2.0 g ? kg-1 ? d-1 being quite safe (102, 117, 118) and that renal considerations are not an issue at this level in individuals with normal renal function


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## Mars (Aug 25, 2007)

The reason that ppl keep coming up with different amounts is because there is no true answer.

The digestive system, GI organ functions and phases are extremely complicated, *thats without even going into neural regulation of the GI tract, hormonal regulation by the endocrine system and chyme concentrations of specific proteins*.

Just a basic look at how protein is digested can have your head swimming.

On a very fundamental note proteins are broken down to peptide fragments by pepsin in the stomach, and by pancreatic trypsin and chemotrypsin in the small intestine. The fragments are then digested to free amino acids by carboxypeptidase from the pancreas and aminopeptidase from the intestinal epithelium. Free amino acids enter the epithelium by secondary active transport and leave it by facilitated diffusion. Small amounts of intact proteins can enter interstitial fluid by endo- and exocytosis.


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## NoGutsNoGlory (Jun 11, 2009)

Epic thread.

Just when you think UK-muscle is all about "how's my first cycle look" a thread like this pops up.

:thumbup1:


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