Protein and Muscle Growth
For Exercise Enthusiast and Athletes
There seems to be a lot of confusion regarding the amount of protein needed to build muscle mass. What builds muscle? True muscle growth; hypertrophy, the enlargement of actual muscle cells and hyperplasia; the growth in the number of muscle cells, are the result of the stress load on muscle fibers from exercise or strenuous work, which initiates the uptake of amino acids in the form of proteins. Excess amino acids (proteins) are burned as fuel or metabolized into fat. Only so much muscle protein synthesis (MPS) can occur. You can’t force feed muscle cells. The first 3 hours after a workout is the time when the majority of MPS will take place.
Guidance from non-nutrition professionals, based on non scientific results can cause potential harm to those that follow such advice.
It is really amazing how many articles I have read from bodybuilding sources that say a person should consume between 2 to 4 grams of protein for every kg of body weight, or that a person should consume 1 to 1 ½ grams of protein per pound of body weight. That would mean a 200 pound man would need to consume between 200 grams and 363 grams of protein daily. The DRI for protein intake under normal bodily demand would be .8 grams of protein for each kg of body weight. For the obese it would be .8 grams for every kg of muscle mass. For an athlete with heavy demands on muscle performance such as a body builder or an Olympic athlete the limit would be 1.6 to 1.7 grams of protein per kg of body weight meaning that same 200 pound man would consume 145 grams of protein at the high end. An endurance athlete such as those running marathons, iron man events and triathlons requires less because they are not placing as much stress on the major muscle groups. Their needs can be met in most cases with no more than 1.2 to 1.4 grams of protein per kg of body weight. The average person who works out in the gym and is very active hiking and playing organized sports does not require this level of protein intake. Consuming high quality complex carbohydrates is equally important because it keeps the body from burning those ingested proteins for fuel allowing the body to use the proteins for MPS.
Protein synthesis is most effective when the body is fed adequate complex carbohydrates so as to be protein sparing. This allows dietary protein to be utilized for protein synthesis for muscle hypertrophy and muscle hyperplasia instead of being burned for fuel. Carbohydrates are the body's first choice for energy and without adequate carbohydrate intake during a meal the body will burn the protein for energy. So make sure at least 50% of your calories are from complex carbohydrates. Weight lifting is an anaerobic action which requires glucose (sugar) for fuel.
Protein is used for many functions not only muscle growth. Protein is required to build and repair muscle cells, hormones, blood cells, enzymes, antibodies and antigens.
The excess intake of protein can cause serious health consequences. The consumption of a high protein diet typically means the person is also consuming excess saturated fats and cholesterol. Excess fats and cholesterol increase LDL and total cholesterol levels increasing the risk for heart disease.
A high protein diet typically results in a lowered consumption of fiber which is critical for colon health. There is no fiber in meat. As noted in Clinical Nutrition a Functional Approach pg. 27, adequate fiber intake is cardioprotective, glucose regulating and cancer protective. Fiber in a bottle is never an equal to fiber from vegetative foods. A recent Japanese study published in the Asian Pacific Journal of Cancer Prevention, 2002 concluded that as dietary animal protein, fats and oils increase, the incidence of colorectal cancer increases. However, colorectal cancer rates decrease as dietary plant protein increases.
As protein replaces vegetative foods the diet could be lacking vital macro and micro nutrients such as vitamins, minerals and phytonutrients that are contained in plant foods and not found in animal food products. A lack of nutrients over time can lead to health issues such as impaired immune function, digestive disorders, fatigue, hormonal imbalances and insulin resistance.
The metabolic synthesis of protein causes different acids to be formed. To neutralize the acids the body must release calcium from bone to bring the body’s pH back into balance. Over time a high intake of proteins can cause osteoporosis. However, certain plant foods that also contain proteins such as grains and legumes contain higher levels of potassium which help decrease urinary calcium loss.
For individuals with decreased kidney function excess protein intake can lead to further impairment of kidney function and even kidney disease.
The very high intake of proteins as recommend by many body building and sports health publications and body building organizations is misleading and can cause bodily harm through the dissemination of incorrect dietary information regarding protein intake.
Excess protein can increase the risk of bone loss, heart disease, obesity, impaired kidney function, cancers and even type II diabetes. The absence of carbohydrate to provide for adequate glucose or glycogen synthesis to fuel the Krebs cycle and neurological functions will cause the body to use the protein for fuel thus reducing the amount of protein that can be used for bodily functions that require dietary protein. When protein intake replaces complex carbohydrates the diet can be denied important phytonutrients that promote health and may even lower the risk of certain diseases. Furthermore, protein does not increase muscle mass or strength. The stress load on muscles triggers the body to use amino acids provided by dietary proteins to form specific proteins for building and repairing muscle tissues, MPS.
Research published in The Journal Physiology 2001 states “Overfeeding protein does not increase the size of the lean body mass, and amino acids supplied in excess of the requirements of protein synthesis are simply oxidized (Motilet al.1981; Priceet al.1994) and their carbon skeletons used for fuel or stored as fat. The rise in plasma urea observed in this study supports this interpretation.”
Some of these individuals will suffer from serious illness and disease from excessive protein intake. Sadly the illness or disease may be caused by their false belief that a high consumption of dietary protein is superior at building muscle mass and muscle strength compared to current DRI recommendations for protein intake.