Walk into any fitness club and you are bound to see the word “protein” on at least half of the items for sale (protein powder, protein shakes, protein bars, etc.). Protein is important for people who exercise because it is responsible for rebuilding your muscle tissues after exercise and also plays a role in producing energy under more extreme training conditions. Exercise also causes muscles to demand more protein because it causes structural damage to muscle tissues. When muscles are damaged (i.e. micro tears) the body needs to rebuild the tissues stronger and/or bigger so that they can handle ongoing challenges. If you exercise and want to get results, you’re probably wondering, “What are the best high protein foods to include in my diet?”
High Protein Foods
Protein is a macronutrient composed of amino acids that is necessary for the proper growth and function of the human body. These macronutrients are an important component of all living cells, including enzymes, hormones and antibodies, all of which are necessary for proper functioning. While the body can manufacture several amino acids required for protein production, a set of essential amino acids (histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan and valine) needs to be obtained from animal and/or vegetable protein sources, including meat, fish, eggs, milk and legumes.
The protein-to-calorie ratio has been used to choose foods that provide the most protein per calorie value. A food with a high protein-to-calorie ratio would provide more protein per calorie. Below is a list of the top 10 food sources with a high protein-to-calorie ratio:
- Turkey or chicken breast (1 gram of protein per 4.5 calories)
- Fish (1 gram of protein per 4.5 calories)
- Low-fat cheese (1gram of protein per 4.7 calories)
- Pork loin (1 gram of protein per 5.2 calories)
- Lean beef (1 gram of protein per 5.3 calories)
- Tofu (1 gram of protein per 7.4 calories)
- Edamame (1 gram of protein per 10.4 calories)
- Egg whites (1 gram of protein per 12 calories)
- Low-fat yogurt, milk or soy milk (1 gram of protein per 18 calories)
- Nuts and seeds (1 gram of protein per 15.8 calories)
Although choosing protein sources by protein-to-calorie ratio may seem like an ideal, it has its flaws. Choosing foods that are high in protein and low in calories may result in an overall diet that is high in protein and lacking in other nutrients essential for proper functioning (i.e. carbohydrates, fats, essential vitamins and minerals). Excessive protein intake is also associated with reduced kidney function. If you choose protein sources solely by protein-to-calorie ratio, it is recommended you ensure you have a diet that includes the recommended daily intake of all essential nutrients, vitamins and minerals.
Protein Digestibility Corrected Amino Acid Score (PDCAAS)
Although there are several sources of protein to choose from, not all sources provide the same quality of protein. The protein digestibility corrected amino acid score (PDCAAS) is a method of evaluating the protein quality based on both amino acid requirements of humans and the ability to digest it (a PDCAAS value of 1.00 is the highest and 0.00 is the lowest). When choosing protein sources, it’s important to eat the right amount and the right kind. Below is a list of food sources with a high PCDAAS value:
- Casein (milk protein) – 1.00
- Egg whites – 1.00
- Soy protein – 1.00
- Whey (milk protein) – 1.00
- Mycoprotein (e.g. Quorn) – 0.99
- Beef – 0.92
- Soybeans – 0.91
- Chickpeas – 0.78
- Black beans – 0.75
- Other legumes – 0.70
Is More Protein Better?
In the case of protein intake, more is not necessarily better. If individuals consume more protein than their body requires, the extra protein is converted to and stored as fat. As a result, consuming large amounts of extra protein in addition to their regular dietary intake can result in weight gain (most likely in the form of fat).
Eating too much protein (from food sources or amino acid supplements) for extended periods of time can be harmful to the body. The body must work harder to break down protein and eliminate harmful byproducts. This can result in:
- Chronic dehydration (protein metabolism requires extra water – utilization/elimination)
- Osteoporosis/Osteopenia (excess protein has been shown to increase the loss of urinary calcium)