This is probably the most common question I am asked as a dietitian. Whether someone is an elite athlete or a casual weight lifter, it seems they all want to supplement with this magic muscle powder. However, most of the population has major misconceptions about what protein is, how your body uses it, and how much you should be consuming.
What Is Protein?
Protein is one of the three major macronutrients (along with carbohydrates and fat) that contain amino acids and nitrogen. There are 20 different amino acids. The human body can synthesize 9 of the amino acids on its own (non-essential amino acids), but cannot synthesize the other 11 amino acids (essential amino acids) and need to be consumed through the diet. Thus, it is important to consume a variety of protein in your diet in order to have a balance of essential and non-essential amino acids. Proteins provide a variety of biochemical functions in the body.
Functions Of Protein
1. Energy – 1 gram of protein = 4 calories
2. Antibodies – to help defend again foreign pathogens (ex: Immunoglobulin G)
3. Muscle building and contraction – (ex: actin and myosin muscle fibers)
4. Messaging – protein hormones help send chemical messages throughout the body (ex: insulin, growth hormone)
6. Transport – transport proteins help move molecules to different parts of the body (ex: hemoglobin)
7. Structure – provide structure and support to cells
8. Enzymes – help to catalyze biochemical reactions (ex: lactase)
Daily Protein Requirements
The general population: 0.8 grams protein/kg body weight OR 10-35% of total energy intake
Endurance athletes: 1.2 – 1.4 grams protein/kg body weight
Resistance-trained athletes: 1.6 – 1.7 grams protein/kg body weight
*Key Point To Remember: These ranges are in KILOGRAMS of body weight, NOT pounds of body weight. (1 kilogram = 2.2 pounds)
Example – For an average 150 lb individual: 150 lbs x (1 kg/2.2 lbs) = 68 kg
68 kg x 0.8 g protein/kg body weight = 55 grams of protein per day
If you don’t feel like doing the calculations, below is a table of the RDA for protein by gender and age.
In general, Americans are consuming well over the RDA for protein. The graph below depicts the average amount of protein consumed by Americans. Throughout the lifespan, the amount of protein is consumed the greatest between the ages of 19-30 years old. Since I am a part of this age group, maybe that is why so many of my peers are asking me questions about how much protein they need.
Amount of Protein in Common Foods:
- 1 oz beef = 7 g
- 1 oz chicken breast = 9 g
- 1 oz soft cheeses = 6 g
- 1 oz medium cheese = 6-7 g
- 1 oz hard cheese = 10 g
- 1 oz tuna = 7 g
- 1 cup soybeans = 29 g
- 1 large egg = 6 g
- 1 oz nuts = 9 g
- 1 oz tofu = 2 g
- 1 slice bread = 2 g
- 1 slice bacon = 3 g
- 2 TB peanut butter = 8 g
- 8 oz milk = 8 g
How Much Is Too Much?
“The more protein I eat, the bigger my muscles will get.” This is not necessarily true. First of all, consuming an excess of calories, whether it’s via protein, carbs, fat, or alcohol…will be stored in the body as fat. Second of all, the human body cannot properly utilize protein beyond a certain amount.
The upper limit for protein is generally 2 grams protein per kg body weight.
Side effects of excess protein consumption include metabolic imbalance, toxicity, nervous system disorders, and kidney problems. When excess protein is consumed, your body uses more water in order to excrete it. For this reason, individuals consuming a high protein diet should also be consuming adequate water in order to prevent dehydration. High protein diets also tend to be higher in cholesterol and saturated fat, which can increase your risk for heart disease and stroke.
Does Whey Protein Aid In Muscle Building?
Please refer to one of my previous blog posts for an in-depth explanation behind the research on whey protein.
1. Most Americans consume far more protein than they need.
2. Consume a variety of different protein sources to get a variety of other nutrients.
3. Do not OVER supplement with protein, this can cause long-term damage to your kidneys as well as your wallet.