What is Protein?
Protein - the building blocks of muscle, and the most important macronutrient for lean muscle repair and growth.
A "protein" can mean many things, but on this page, we are mainly going to talk about dietary protein, and how it relates to health, muscle building, and weight loss.
Protein is made up of amino
usable forms of protein.
There are 20
that mix and match to make a variety of proteins. Proteins are in
our tissues, cells, glands, skin, organs, hormones, enzymes,
and--except for bile and urine--bodily fluids. [1, 2 and 7]
Functions and Types of Protein
Proteins do just about everything:
Helps repair damaged cells, tissues, and structures, and also help make new ones. It has a hand in the growth and development of nearly every living being. [1 and 10]
Gives skin, nails, hair and bone their unique structure. (collagen and keratin)
bone and skin their elasticity. (collagen)
- Provides energy when carbohydrates and fat aren't available. Protein can also be converted to glucose for energy.
Aids chemical reactions. (enzymes)
Serve as chemical messengers. (hormones)
Regulates vascular system fluid levels. (blood proteins)
Helps maintain pH levels in bodily fluids. (buffers)
Aids the immune system (antibodies)
Food-Based Sources of Protein
Despite being a website that sells a large amount of protein supplements and powders, we highly recommend that the majority of your dietary protein comes from real food, such as those listed below.
Meat - Beef, Pork, Buffalo, etc
Poultry - Chicken, Turkey
Eggs and Egg Whites
Dried beans and peas 
Nuts and Nut Butters--for example peanut, walnut, almond, and pistachio 
Types of Protein Supplements:
Although we want readers to get a majority of protein from food, it is often difficult (but not impossible) to do it without supplementation - especially when trying to build new muscle.
This is why we also recommend supplementing with products featured on this page:
Whey Protein: This protein is found in milk, and is a good choice after heavy duty workouts. It absorbs quickly and doesn’t stay in your body long.
Thanks to the (typically) high levels of the amino acid l-leucine, it is very anabolic and promotes muscle growth more than other types of protein supplements.
Casein: This protein dominates milk, and is a good meal replacement choice. You can also take it before bed. It’s slow to absorb and sticks around in your body longer.
Soy: This is a plant-based protein. It’s used for meal replacement, is a source of antioxidants, and is easily digestible.
Warning about Soy Protein:However, some, but not all, studies have shown that soy may affect hormonal balances in some people, so use caution. One study showed it lowering testosterone levels in men. [16, 17, and 18]
Egg: This protein is found in egg whites. It’s fat-free and cholesterol-free. It also is rich in potassium which aids muscle contraction. Egg protein also aids muscle repair after a workout. It absorbs quickly and is easily digestible. Egg protein contains all essential amino acids. 
Bulk egg whites can also be purchased through this website and are an incredible aid in dieting.
Rice: This protein comes from brown, white and whole grain rice and is easy to digest. It’s good for body builders and often tastes great.
It’s packed with nutrients including essential amino acids, fiber, carbohydrates, and vitamins (B and E). It’s free of fat, cholesterol, sugar and salt, too. 
This protein comes from milk and is slow to digest. It helps build
muscle over time and preserve it.
As a thick type of protein powder, it will often yield a better-tasting protein than whey alone. Milk protein contains all essential amino acids and includes both whey and casein forms. 
- Pea Protein - This is a new form of protein powder, and has very high digestibility. It's great for those allergic to whey/casein/milk who also don't want to touch processed soy.
While it is relatively new, research studies are showing that it is helpful in the areas of cholesterol and triglyceride levels.[21,22]
Types of Amino Acids in Protein
Proteins are the building blocks of muscles, but amino acids are the building blocks of your protein. Your protein powder is only as good as the amino acids underneath it.
Essential Amino Acids:
These can’t be made by the body, so you need to get them from food. Spread them out over the course of a whole day. 
The first three of these are the branched-chain amino acids, or BCAAs. They are the most important ones for muscle repair and growth. Of these three, L-Leucine is the one that is critical for muscle growth and repair.
If there was ONE bullet point to take away from this entire section, it is that your protein powder should state how much leucine is in it, and it should not be one of the smaller numbers in the amino acid breakdown.
Nonessential Amino Acids:
The body makes these from essential amino acids and from protein breakdown. 
Conditional Amino Acids: These become essential when illness or stress strike. 
Important Note about Glycine and Taurine in your Protein!!!
Be very wary of protein supplements that include this as an added ingredient.
It is cheap and is used to "cheat" the amount of protein listed on the label higher than it should be (it is "protein" according to the scientific definition and the FDA, but isn't seriously dietary protein). The same goes for another amino acid, Taurine.
When you see these listed as an *added* ingredient on the ingredient list, RUN. You are potentially being ripped off and not getting the true dietary amount of protein.
How Much Protein Do You Need?
Your daily diet should consist of anywhere from 10 to 40 percent protein. This is an extremely vague amount because it really depends on who you are, what you're doing, what your dietary beliefs are... and what exactly you're training for.
For athletes, the amount needed depends on age and purpose, but it’s always related to weight.
When in doubt, get a gram of protein per pound of bodyweight every single day. If you are not extremely overweight, you can't go wrong starting here. But the studies referenced below have shown success at both higher and lower numbers, depending on activity.
Here are the minimum numbers we recommend, but several professionals go 2-4 times higher:
Recreational: .5-.75 grams per pound of body weight daily
Competitive: .6-.9 grams per pound
Teen: .8-.9 grams per pound
Building muscle mass: .7-.9 per opund
Other sources put the general range for exercisers at 1.4 to 2 grams per pound of body weight, with endurance athletes needing 1 to 1.6 grams per pound depending on exercise intensity and duration, plus the athlete’s training status, and strength and power athletes needing 1.6 to 2 grams per kilogram.
We highly recommend using a food scale and a calorie counting app to help truly understand your goals.
Just Start with 1g Per Pound Every Day
Again, the safe number for most people is 1g of protein per pound of bodyweight, every day - even rest days. Space it out throughout the day, and get it from both food and supplements - try to vary the foods up to get a broad range of amino acids.
For a 160lb male, getting ~175g of protein each and every day is not as easy as it seems. Consistency is key. Build your diet around that number... but this is where protein supplementation with the powders listed above comes in handy.
If you are seeing decent muscle-building results yet want even more, you can add even more protein, carbs, and consider some saturated fats.
The General Population's Needs
The recommended daily dietary allowances for the general population are: 
Children (1 to 3 years): 13 grams
Children (4 to 8 years): 19 grams
Children (9 to 13 years): 34 grams
Girls (14 to 18 years): 46 grams
(14 to 18 years): 52 grams
(19 to 70+ years): 46 grams
(19 to 70+) years: 56 grams
Check out nutrition labels and you’ll see that it really isn’t difficult to get enough protein. People in industrialized countries like the U.S. often end up getting more than they need, especially animal protein. [6 and 8]
It's the serious athletes and weight loss dieters that really need to focus on getting more of it.
We've already discussed several benefits above, in terms of building muscle. But there are even more:
Protein And Exercise
Protein builds and repairs tissues.
Amino acids provide quick energy when carbohydrates and fats aren’t available.
The reduction of calories to facilitate weight loss may necessitate more protein intake since you may not have enough carbohydrates and fat to provide needed energy. Be sure to eat enough complex, or “healthy,” carbohydrates and healthy fats to help prevent protein sparing.
Protein For Weight Loss
Protein may aid weight loss efforts in the following ways: 
Satiety: Protein boosts the feeling of satisfaction or “fullness,” that may reduce total calorie consumption.
Thermogenesis: Thermogenesis is the generation of heat by the body. Protein tends to increase it, thus, positively affecting satiety and energy expenditure.
Fat-free mass growth and maintenance: Protein provides slow muscle growth over time and helps preserve it.
But also consider these points: 
The key to "weight loss", in general, is taking in fewer calories than you burn. However, we are more concerned with fat loss, which requires a shift from processed carbohydrates to natural proteins, fats, and vegetables.
Although replacing a meal here and there with a protein shake may help cut calories and lead to weight loss, if you make a habit of this, you’ll be missing out on important "micronutrients" that whole foods provide.
Protein still contains calories, and overconsuming it can still lead to weight gain and fat storage:
If you take in more protein than is needed for energy and making other proteins, then the excess is stored as fat. So don’t overdose on protein thinking it will help build bigger muscles. It might backfire and cause unwanted weight gain instead. [3 and 11]
If you fill up on protein, you may skip eating vegetables and fruits that are also required for optimal bodily function. 
Excessive protein consumption may alter hormones and hormonal responses. And the hormone leptin is involved in regulating brain-based feeding centers to curb eating. 
Stick to a balanced, healthful diet that includes fruits, vegetables, healthy fats, and lean protein, and get regular daily exercise to aid weight loss. 
That all said, one of the best studies shown was when a whey protein shake was consumed prior to breakfast. This led to incredible amounts of fat loss, as it then curbed appetite for (and replaced) more fat-inducing carbohydrates such as cereal grains.
Protein Deficiency and Toxicity
May lead to dehydration since metabolizing protein requires a lot of water. Drink plenty of fluids when consuming protein to help flush the by-products of protein breakdown out of your system. [3 and 9]
Can cause excessive urinary calcium loss, which can lead to osteoporosis, especially in women. 
Most likely happens due to taking in too much supplemental protein. 
Can cause kidney function issues, especially in people with kidney problems or diabetes. 
Happens when you don’t get enough protein, or energy in the form of carbohydrates and fats. 
Happens when you don’t get enough quality or absorbable protein. 
Vegetarians have to be careful not to become protein deficient, as do people who exercise but also restrict calories. Consult a registered dietician if you need help managing your protein intake. [5, 8, and 9]
Protein Powders and Shakes
There are many forms of protein powder, as mentioned above, but the most common are casein, whey and soy, with whey being the most used. Powders provide complete protein. They’re convenient and portable. 
The best times to use protein powder are: [4 and 12]
When starting a new program, especially with the goal of muscle building
When recovering from an injury
When you’re increasing the intensity of your workout
When you’re switching to a vegan or vegetarian diet
Protein shakes are available in a variety of combinations of protein, carbohydrates, and fats. Some have just protein while others have mostly carbohydrates. They are available in powder form to add to beverages, or ready-made in a variety of containers. Shakes are often used by athletes right after a workout to restore energy.
Some benefits of protein shakes include: 
Helping the body recover from heavy duty exercise
Replenishing muscle glycogen stores for endurance athletes
Repairing muscle damage that occurs during major bodybuilding
Recovering after tough general fitness workouts
Note that you do not need to use protein powders and shakes if you eat a healthy, balanced diet that includes fish, chicken, meat and dairy. 
Safety and Side Effects
It's important to separate the side effects of eating low-quality meat from the side effects of protein itself. This is a distinction that is never made on other resources.
But first, we need to clear one thing up:
Protein Supplementation is SAFE For Kidney Function!!!
The objection most frequently given to protein supplementation is that "it's bad for the kidneys". This is one of those things that is now in the territory of "if people say it enough, it has to be true".
In fact, for healthy individuals with normally functioning kidneys, nothing could be further from the truth. Studies show that renal function is perfectly fine for normal people, and this whole "protein is bad for your kidneys" is one of the most baseless old-wives tales we see in this industry.
Protein Kidney Study 1
High protein supplementation led to still-normal clearance rates of creatinine, urea, and albumin. Protein under 2.8g per kg (a whopping six grams of protein per pound of bodyweight!) did NOT impair renal function in athletes.
Protein Kidney Study 2
A meta-analysis of all other studies showed that healthy individuals are fine with additional amounts of protein. When given extra protein, adaptive processes likely occur in the body, yet are all within normal function.
This study essentially states that "not a single study has come close to proving protein is bad for healthy individuals", yet does not "prove it is healthy" either. It simply has NOT shown to be a problem, and does not recommend restriction.
Now, back to the "meat vs. protein" issue, here are some notes:
Excessive meat consumption, especially beef which is not grass-fed, can lead to high cholesterol and gout, and, as mentioned, kidney issues. Limit fatty cuts of meat, regular, processed lunch meats, liver, egg yolks, and duck to reduce cholesterol problems. [1 and 7]
We are not going to get into the egg debate here, but needless to say, if you are eating whole eggs as a primary protein source, you will be taking in additional cholesterol and fat. Whether or not that is bad for you is in constant debate.
High cholesterol diets can boost LDL (“bad”) cholesterol levels. 
The benefits of eating seafood are greater than the risks of the mercury levels it contains. 
Nuts and seeds are good sources of protein, but steer clear of the salted varieties. 
Do not consume whey or casein protein if you have a dairy allergy or intolerance. 
Things to Consider
Healthy, non-athletic people with proper diets rarely need supplemental protein. [1 and 2]
Be sure to read the label on any protein supplement to make sure it’s right for you. 
Although we do not physically sell protein supplements, you can compare quality and price here on PricePlow.com
Check out other reliable sources such as peer reviewed journals for information on protein. Educate yourself about what you put into your body!
Adopting a healthy lifestyle, including regular exercise, healthful diet, and plenty of sleep, can help improve and maintain your overall health and wellness.
Please note that we are not doctors. We take no responsibility for the products listed here since we do not manufacture them.
Where to Buy Protein
Protein is expensive, and it is going up in price every month (with no end to this trend in sight). You can see the product listings on this page and save over 40% off retail prices by shopping online and using the Price Comparisons on PricePlow.com.
9. “Nutrition;” Fourth Edition; Paul Insel, et. al; 2011
10. “NASM Essentials of Personal Fitness Training;” Third Edition; Michael A. Clark, et. al.; 2008