I am often asked how much protein should a person consume in a day, and how much can their body absorb in one sitting?
Well you will commonly receive different answers to these questions as it is a complex subject, so I will answer to the best of my ability with the knowledge I have gained and try to offer an insight into this.
I will start with the science of protein absorption.
When protein is consumed it is broken down into amino acids within the stomach. These amino acids are driven into the bloodstream by cells that line the small intestine and delivered to different parts of the body. The small intestine has a limited amount of transporter cells which only allows a certain amount of amino acids to be added to the blood stream every hour (Protein Absorption).
This now becomes complicated as different proteins are absorbed more quickly than others. This is simply why most of us utilise whey protein after our workout as this protein is absorbed more quickly than casein or soy.
The common amount of protein we read that the body can absorb in one sitting is between 30 and 40 grams, and any more is converted into glucose and burned. This is based on the theory that all foods pass through the intestines in 2-3 hours – a theory which is flawed. The body actually regulates the speed that the protein passes through the small intestine ensuring it can absorb all the supplied amino acids. Also food particles do not move through the digestive system at the same rate, and some may leave in a different order than they arrived in. A good example of this is when protein is consumed it stimulates the production of a hormone that delays the food being emptied from the stomach; this allows your body more time to absorb the protein.
So if we stuck to the theory that all foods pass through the small intestine in 2-3 hours you could only absorb 30-40 grams of of a fast absorbing protein such as whey before it ended its journey. But as I have explained the body regulates the speed at which protein moves through the digestive tract which in turn would inform us that the body can absorb more than 30-40 grams per sitting, and there are some studies to support this.
So how much protein should we consume to gain muscle? This can be complicated as it is based on such things as exercise intensity, duration and type, your gender, age and numerous other factors. So there is not a “one size fits all” to protein intake.
So as there is no definitive answer to your body’s protein requirements I will offer what we do know; bodybuilders have for decades worked with 1g of protein per pound of body weight or 2.2g per kg of body weight. If you are cutting (fat reduction) this can be increased up to 1.5 per pound of BW or 3.3 kg of BW. I believe the latter to be high but this information was gained from a study on resistance trained athletes.
Personally I consume about 1.2 grams of protein per pound of body weight as generally I just enjoy consuming protein based foods. Also I am aware as I age my body has a greater need for protein.
If we are weight training to increase muscle mass it should not be a surprise to know that a high protein diet can assist in building muscle faster. When we train for hypertrophy we are breaking down the muscle tissue and creating “protein synthesis” which is the body forming new muscle to replace the tissue you have just damaged. So a high protein diet is important to support resistance training and increase in strength.
A high protein diet is also important during cutting or fat loss diet. When we lose weight the goal is to reduce body fat but maintain our muscle mass which is extremely important for body builders. A high protein diet is great for both fat loss and retaining muscle mass as protein increases satiety and maintains muscle mass.
A high protein diet also assists with muscle and bone health as we age.
Also note that not all proteins are equal, so here is a brief insight-
Egg – Digested slowly and 90% of what is consumed is utilised by the body. Beef – Digested quickly and 70-80% of what is consumed is utilised by the body. Whey – Digested quickly and 90% of what is consumed is utilised by the body.
A good choice for vegans would be quinoa, beans and high protein vegetables such as peas.
Protein timing is also not as important as we were led to believe, but some studies state that pre and post workout protein can assist in building more muscle.
My preference is to consume protein about 90 minutes pre workout and within 30 minutes post workout as some evidence for supporting muscle growth is good enough for me. Plus it just feels right!
There were some claims flying around that a high protein diet can cause kidney damage, osteoporosis and be carcinogenic, but this is not supported by sound scientific research.
A high protein diet has never been proven to cause kidney damage in a healthy individual but a person with pre-existing kidney damage or dysfunction should restrict their protein intake.
In fact the above claims are ironic as a high protein diet can lower blood pressure and improve glucose control in diabetics which could decrease the risk of kidney disease and also improve bone health reducing the risk of osteoporosis.
As protein absorption is a complex topic and this is definitely not a concise blog I offer a synopsis below-
The body can absorb larger amounts of protein per sitting than 40 grams. The actual amount is unclear.If you are training for hypertrophy you should consume around 1 gram per pound or 2.2 grams per kilo of body weight.You do not have to consume protein every few hours to feed the muscles as long as you are reaching your daily target.Your muscles will not deteriorate if you do not consume protein every few hours.Eating protein more frequently will not help you build more muscle.Consuming larger amounts of protein less frequently has the same result on muscle mass as eating small protein meals more frequently.There is some evidence that consuming protein pre and post workout can assist in building more muscle.A high protein diet has no risks associated with it.A high protein diet is important to build muscle and increase strength.A high protein diet is important while lowering body fat and maintaining muscle mass.A high protein diet increases satiety whilst on a fat loss diet.A high protein diet is great for bone and muscle health as we age.
Any questions on protein intake?
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