All About Protein Intake
What is so important about protein?
The building blocks of protein, amino acids, are made up of carbon, hydrogen, nitrogen, an acid group and a side chain. The side chain and nitrogen differentiate protein from the other major nutrients, fat and carbohydrate. The side chain makes an amino acid unique. According to the World Health Organization, the human body recognizes 20 amino acids. Nine of these are nonessential because the body makes them. Eleven amino acids are essential, or those you must obtain from foods. In addition to building muscle, protein is used to build cells and manufacture hormones, antibodies and enzymes.
How much protein per day should I eat?
Protein is measured in grams. A healthy adult male needs approximately 56 g/day of protein and a female, because she has less muscle mass, requires approximately 46 g/day. Protein contains nitrogen, a substance essential for health. In terms of protein needs according to life stage group, infants, children, adolescents and adults are taking in enough protein when able to maintain nitrogen equilibrium or balance. To give you a point of reference, a 4oz chicken breast has about 28 g of protein and 16oz of milk, 16 g.
What is the Recommended Daily Allowance for protein and/or how much protein do I need per lb of body weight?
The U.S. Department of Agriculture has set a Recommended Dietary Allowance (RDA) for protein. This intake value is based on body weight. To calculate your protein needs, you should know your weight, in lbs or kg. If you are using lbs, the calculation is 0.36 g/lb and if you are using kg, it is 0.8 g/kg. Thus, a woman that weighs 130 lbs needs approximately 40 g of protein daily. Overweight or obese individuals may need to use an adjusted formula to calculate protein needs. Some experts feel that the RDA is too low, and Americans should strive to consume more protein daily, about 0.5 g/lb. However, most Americans consume a ‘Western-style’ diet, heavy in animal protein, thus exceeding the protein RDA regularly.
How much protein per day do I need to gain muscle?
According to experts, such as MR Etzel et al, the quality of the protein you choose may be more important than the quantity for building lean body mass. Three of the essential amino acids, known collectively as ‘branched chain amino acids’ or BCAAs, are the most important for building skeletal muscle. In fact these A.A.s alone make up 1/3 of the skeletal muscle in the human body. Leucine, Isoleucine and Valine create their own metabolic pathways for building muscle tissue and leucine is the only A.A. with the capacity to actually stimulate protein synthesis. It is important to note that consuming adequate protein is essential for building muscle but simply eating more protein than necessary does not create more/bigger muscles.
How much protein is too much?
There is not a Tolerable Upper Intake Level (UL) for protein however, the U.S. Department of Agriculture has set an Acceptable Macronutrient Distribution Range for the three major nutrients. About 15 to 25% of your calories should come from protein. For an individual on a 2,000-calorie diet, 25% of total calories, or 500 calories from protein equals about 125 g. This is one way to set a limit on protein and regularly exceeding this amount may be ‘too much’.
Which foods are rich in protein?
Animal foods, such as dairy products, meat, fish and poultry are high in protein and contain all of the essential amino acids, as do soy foods and quinoa. Other plant foods are missing one or more of the essential amino acids so it is important to strive to consume a wide variety of foods. Foods rich in BCAAs, particularly leucine, include whey protein, soy protein (isolate or concentrate), white fish, milk, tofu, Parmesan cheese, soy flour and sesame seeds. A 100 g serving of any of these foods offers 3-6 g of leucine. In addition to stimulating muscle synthesis, it inhibits the breakdown of muscle tissue.
- Etzel MR et al. Manufacture and Use of Diary Protein Fractions. Journal of Nutrition. 2004; 134 (4) 996S – 1002S.
- National Nutrition Database for Standard Reference. U.S. Department of Agriculture. Retrieved 2011 – May 30.