"In fact, medical research shows that consuming too much protein -- more than 30% of your total daily caloric intake -- could actually harm your body, says protein expert Gail Butterfield, PhD, RD, director of Nutrition Studies at the Palo Alto Veterans' Administration Medical Center and nutrition lecturer at Stanford University.
She says that a diet containing excess protein can have the following adverse effects:
Adding more protein but not more calories or exercise to your diet won't help you build more muscle mass, but it may put your other bodily systems under stress.
Eating more protein and increasing total caloric intake while maintaining the same exercise level will build an equal amount of additional fat and muscle mass, according to a study published in 1992 in the Journal of the American Geriatrics Society. "
"Drastically cutting carbohydrates from your diet may force your body to fight back.
She says that's because a diet in which protein makes up more than 30% of your caloric intake causes a buildup of toxic ketones. So-called ketogenic diets can thrust your kidneys into overdrive in order to flush these ketones from your body. As your kidneys rid your body of these toxic ketones, you can lose a significant amount of water, which puts you at risk of dehydration, particularly if you exercise heavily."
http://www.medicinenet.com/script/ma...ticlekey=50900
"How Much Protein Do You Need?
Robert M. Russell, M.D., and Carmen Castanada Sceppa, M.D., Ph.D.
Carmen Castanada Sceppa, M.D, Ph.D., is a scientist working at the Jean Mayer USDA/Human Nutrition Research Center on Aging at Tufts University School of Medicine. Carmen's research emphasizes protein nutrition and physiological function of healthy older individuals and those with chronic illnesses.
RMR
How does the average intake in the United States measure up against the Recommended Dietary Allowance (RDA) for protein?
CCS
The typical American diet provides plenty of protein -- more than the RDA in most instances. The RDA represents the minimum amount of protein needed to fulfill protein needs in 97.5% of the population.
This value is equal to 0.8 g of protein per kg body weight per day. The average mixed American diet provides from one to two times the RDA for protein. You might think, then, based on this that protein deficiency is unlikely in the U.S. . However, the RDA for protein has been derived from research studies performed on healthy individuals. Growing children, pregnant and lactating women, the elderly, and anyone undergoing severe stress (trauma, hospitalization, surgery), disease or disability need more protein.
RMR
What if you exercise?
CCS
We have seen in our lab that individuals undergoing endurance training increase their protein needs to about 1 to 1.2 g per kg per day, well above the RDA. In contrast, for subjects performing resistance exercises or weight lifting, the RDA for protein seems to be adequate. In resistance training, you are building up muscle and protein is used more efficiently.
Muscles are built from protein.
Unlike fat cells for fat and muscle or liver for glucose, there is no place in the body to store protein. We need to consume enough protein to allow our muscles to be healthy and perform work.
RMR
Carmen, we hear a lot in the media about balancing different types of proteins. What are the best sources of protein and what exactly is meant by complementary proteins?
CCS
Animal and plant or vegetable foods are the two major protein sources. Animal protein foods include meat, poultry, fish, dairy products and eggs and are said to be of high biological value. That is, they contain all nine essential amino acids that can not be synthesized in the body (histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan and valine).
Plant protein sources, although good for certain essential amino acids, do not always offer all nine essential amino acids in a single given food. For example, legumes lack methionine, while grains lack lysine.
What is needed are complementary proteins, various protein food sources that, eaten together, enable a person to meet the standards of a high biologic protein diet.
RMR
Do vegetarians and people on macrobiotic diets get into problems with protein malnutrition?
CCS
There are two types of vegetarians. Lacto-ovo vegetarians and strict vegetarians or "vegans".
Lacto vegetarians eat animal protein of high biological value, eggs and dairy products. Vegans, however, eat a more limited diet and often must take amino acids supplements to make up for their not-so-high biological protein diet.
If vegans eat a variety of plant foods -- cereals, nuts, seeds, grains and legumes -- they'll be fine. They don't have to eat all these food items at a given meal. However, they should consume most or all of them during the course of the day to insure a well balanced protein diet of high biological value.
RMR
Can one take in too much protein?
CCS
The typical American diet, as we said earlier, is already providing plenty of protein. There is no value in adding even more protein to that amount, since protein cannot be stored in the body and the excess is eliminated in urine and feces.
When people start consuming too much protein (over 2.0 g/kg/d), the extra protein can become a stressful stimulus for the kidney. This is even more of a concern as we get older and our organs are less efficient and effective.
Very high levels of dietary protein have also been correlated with increased urinary calcium excretion. The loss of calcium through urine could potentially be harmful for bone turnover, with the added risk of osteoporosis. Finally, protein requires vitamin B6 in order to be metabolized and ultimately utilized in the body. Very high levels of dietary protein increase the requirement for this B vitamin."
http://www.thedoctorwillseeyounow.co...n/protein_2/#2
aaand for good measure, let's quote the good ol' American Heart Association:
"The American Heart Association doesn't recommend high-protein diets for weight loss. Some of these diets restrict healthful foods that provide essential nutrients and don't provide the variety of foods needed to adequately meet nutritional needs. People who stay on these diets very long may not get enough vitamins and minerals and face other potential health risks."
"But these diets have other effects besides inducing quick weight loss. Most Americans already eat more protein than their bodies need. And eating too much protein can increase health risks. High-protein animal foods are usually also high in saturated fat. Eating large amounts of high-fat foods for a sustained period raises the risk of coronary heart disease, diabetes, stroke and several types of cancer. People who can't use excess protein effectively may be at higher risk of kidney and liver disorders, and osteoporosis."
http://www.americanheart.org/present...entifier=11234
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