How much protein does an active person need?
Protein has a mainly structural purpose in the body; the amino acids that result from the digestion of protein are used for the synthesis of non essential amino acids and other various compounds (different hormones, cell components etc.).Besides the small amount of amino acids floating around in the blood stream and in the muscles, the body has no “real” storage mechanism for amino acids.
Because of this, it is critical to supply through your diet the amino acids the body needs for synthesis purposes. Failing to do so causes protein deficiency. When in a prolonged state of protein deficiency the body reacts by breaking down muscle tissue and, eventually, organ tissue to provide for it’s basic amino acid needs.
Now that you now what happens when the body is protein deprived, let’s tackle the issue of what is the minimum amount of protein a person needs to ingest in order to prevent muscle and organ tissue wastage and eventual death.
Before we talk numbers, a quick word on how protein needs are measured. The technique used to measure protein needs in different populations is the nitrogen balance technique.
The technique involves measuring the amount of nitrogen ingested (found in protein sources) and the amount eliminated through urine, sweat and feces.
When nitrogen coming in is equivalent to the amount being eliminated then there is nitrogen balance. What this means is that you are eating enough protein to prevent muscle and organ tissue breakdown but not enough to support the “building” of additional muscle tissue.
The results of studies conducted on nitrogen balance suggest that an amount of 0.8 g of protein per kilogram of body mass should be consumed by sedentary people in order to maintain nitrogen balance.
As for minimal protein need of active people:
- A Rennie et al (1999) study showed that undergoing new training programs leads to a short term increase in protein needs and that this increase does not persist in the long term.
- A Butterfield and Calloway (1984) study suggests that chronical training leads to increased anabolic efficiency (more efficient protein use) therefore reducing the minimal amount of protein needed to maintain nitrogen balance. What this means is that active people may need less then the 0.8 g protein per kg required by sedentary people. The amount suggested is around 0.65 g protein per kg.
Now for the actual optimization part
In the section previous section I’ve indicated that studies suggest that a intake between 0.65 and 0.8 g protein per kg of body mass is enough to maintain nitrogen balance.
The amount of protein that is recommended as being optimum, when fat loss is the main goal, is between 1.5 and 2 g per kg.
Some people find these recommendations excessive because, after all 2 g per kg is 2.5 times more then the minimal amount recommended (0.8g per kg). These are the same people that have a limited view of protein, considering it to be a macro nutrient that provides nothing beyond preventing protein deficiency. A better understanding of how protein fits into one’s dietary strategy will erase this fear out of the heads of even the most skeptic people.
Studies made on the effect of increasing protein intake have showed that there are clear benefits to increasing protein intake. Some of the benefits are:
- Increased termic effect of food.
The digestion, absorption, storage and oxidation of all nutrients require metabolic processing. The termic effect of processing protein is roughly double than that of carbohydrates and fats. So eating protein is termogenic and leads to a faster metabolic rate. This translates to greater fat loss when dieting. - Increased glucagon production.
Protein consumption increases the glucagon to insulin ratio. - Increased IGF-1 secretion
Protein supplementation, above minimum needs, has been proven to increase the IGF-1 response to exercise and feeding. IGF-1 is an anabolic hormone related to muscle growth. Increased IGF-1 levels while dieting translate to better muscle sparring. - Improved weight loss profile
A 2003 Layman et al study has revealed that reducing the carbohydrate to protein ratio from 3.5-1 to 1.4-1 has the following benefits:
- increased body fat loss
- spares muscle mass
- improves satiety
- better blood glucose management - Increased nitrogen status.
Diets high in protein cause a strong positive nitrogen balance. This coupled with proper exercise leads to the acceleration of muscle growth.
The multiple benefits listed above justify the suggested increase of protein consumption to 2 g per kg or even above.
Further Reading
- The Protein Roundtable, Refereed by John M. Berardi
- The protein Insider - An Inside Look at the Protein Business, by TC
- The Protein Debate, by Dr. John M. Berardi
- Soy is Still Bad Protein, by Glen Neilson
0 comments:
Post a Comment