The word "protein" is rooted in the Greek "protas," meaning "of primary importance." Proteins are involved in practically every function performed by a cell, including regulation of metabolism. Proteins control almost all the molecular processes of the body and are the actors that do everything that happens within us. Yet, protein is perhaps the most undervalued macronutrient in our dietary recommendations. How much we should eat isn't well defined but recommended as a default percentage of calories based on consumption of 55-60% carbohydrate and less than 30% fat. Basically we're told to consume 10-15% of our diet as protein.
But, not all protein sources are created equal. Within our food supply there are foods rich with complete protein - that is containing all of the essential amino acids required by humans; then there are foods that contain protein but are incomplete sources due to one or more amino acid being deficient to meet human requirements for amino acids.
Now one would think that since we have essential requirements for specific amino acids, the advice we receive would include a recommendation to eat those foods rich with our required amino acids. Unfortunately the opposite is true - we are specifically encouraged to eat sources of incomplete proteins rather than rich sources of complete proteins!Which foods are our best sources of complete protein? Animal foods - meat, poultry, fish, game, and dairy products. The very foods our dietary recommendations implore us to avoid or strictly limit in our diet.The question begs - what does the research data tell us?
Again and again we find that protein rich foods - specifically those foods that contain complete proteins - protect us from overeating. Two new studies recently published highlight the importance of protein in our diet and the effect amino acids have on our appetite.
The first study, conducted at the Genome Research Institute, demonstrated that the signaling pathway known as mTOR, plays a role in the brain's ability to sense how much energy the body has available. It is activated by nutrient and hormonal signals, and suggests that very specific micronutrients drive these pathways in the brain and help regulate body weight.
Which micronutrient was the center of the study? Leucine - an essential amino acid found in high amounts in meat, fish, poultry and dairy products like cheese. As Dr. Randy Seeley, PhD, lead author of the study said "Rather than basing our diets only on macronutrients like fat or carbohydrates, we might one day be designing diets based on micronutrients like amino acids."
The second study, conducted by researchers at from Imperial College London, investigated the effect of oxyntomodulin - an amino acid peptide hormone. Not only did the hormone reduce appetite, it also increased energy expenditure in study subjects. The effect of oxyntomodulin did this - not specific direction to increase activity levels or specific dietary advice to eat less food!
These two studies add to the data from previous studies that find protein - specifically amino acids from protein rich foods - plays an important part in our metabolism. Add to this the fact that our level of satiety when we eat directly influences our calorie intake at the meal we are consuming and also directly influences when we will feel hungry again and one must ask why our recommendations are encouraging consumption of carbohydrate to the detriment of protein!
When we eat excessive carbohydrate - and 55-60% of calories from carbohydrate IS excessive - we limit our consumption of other sources of nutrients, specifically fats and protein. Those foods that have the highest amounts of complete protein also come packed with fat.
I don't think so. I believe that our food chain specifically provides for our dietary requirements if we eat foods our metabolism is "programmed" to use efficiently. It's no coincidence that diets that restrict carbohydrate and allow ad libitum consumption of fats and protein result in a reduced calorie intake.
The reason is simple - such diets stabilize the hormones responsible for hunger and appetite. I've been saying it for years - the Standard American Diet (how most Americans eat) and the US Dietary Guidelines (how Americans are told to eat) - are nutrient-poor diets that lead to overeating. Until we step back from our assumptions about "healthy eating" and actually recommend eating a nutrient-dense diet based on human metabolism we're not going to reverse the obesity epidemic that plagues us.
We have the necessary information to make a difference in the lives of millions of people in the United States who are obese, overweight and/or suffering the effects of their poor diet. We can reverse the obesity epidemic - with the truth.
And that truth is that we must recommend a reduction in the level of carbohydrate in our diet to allow for adequate consumption of essential amino acids (protein) and adequate consumption of essential fatty acids (fats). We have no requirement for carbohydrate - we do however have essential requirements for amino acids, fatty acids and micronutrients such as vitamins and minerals. We do not need to be consuming excessive carbohydrate to meet those dietary requriements - non-starchy vegetables and some fruits, nuts and seeds with perhaps occassional legumes or whole grains can and will provide all essential micronutrients when one is also consuming adequate levels of complete protein and fat containing foods.