We've decided to do a follow-up article addressing the best questions (see the end of this article to see previous articles) we received in our comments section and on our social media platforms. We received many great responses from the "Protein Myths" article that we published not too long ago, and along with these responses, more great questions surfaced that we felt needed more in-depth explanations.
When calculating total protein requirements, is it dependent on total body weight or just lean body mass?
In most cases, protein requirements are given on a "per pound" basis, meaning total body mass. So if a trainer tells you, "I've been eating 1 gram of protein per pound of my body weight and I weigh 200 pounds," that means he is eating 200 grams of protein. He is not taking into account his lean body mass, which is less than 200.
For the general population, calculating protein intake per pound of total body mass is probably reasonable, but for specific populations, it isn't as reliable. There have been studies showing that the leaner an athlete is, the more protein he or she needs to maintain muscle mass. A study in 2011 found that the leaner the athlete was, the more protein she required to prevent muscle loss (1).
Another study, from 2013, also found that protein requirements for maintaining muscle mass increased in individuals who became leaner through caloric restriction (2). This study suggests that while dieting, lean athletes need 2.3 - 3.1 grams of protein per kilogram of lean body mass (LBM).
It's also important to remember that overweight or obese individuals need to consider protein requirements on a "per kilogram of lean body mass" basis. If a person weighs 350 pounds, but most of that is fat tissue, there is no reason for them to eat 350 grams of protein per day; that would be overkill.
So, to summarize, if you are in the "specific populations" category, such as an extremely lean athlete, or dieting to achieve a very low percent body fat, or are heavily overweight or obese, consider calculating your protein requirements according to your lean body mass, not total body weight.
To find out your lean body mass, you need to first measure your body fat. You can have a professional trainer measure it with skin fold calipers or use a handheld electrical impedance monitor—although these aren't the most accurate. If you have a university nearby and are willing to spend a few bucks, you can see if they have a BodPod device, which uses air displacement for better accuracy. (These are very accurate—DEXA is the gold standard).
Once you know your body fat percentage, you can easily determine how much of your body weight is lean mass and how much is fat mass. For example, if you weigh 200 pounds and you find out that you have 20% body fat, you have 40 pounds of fat. Subtract 40 pounds from 200, and you have 160 pounds of lean body mass.
If I eat too much protein, will the excess be turned into body fat?
First let's assume that your maintenance amount of calories—the number of calories you need to eat per day to maintain your current body weight—is 2,000 calories. Let's also assume that you have met your 2,000 calorie goal by the end of the day, with a mix of protein, fat, and carbohydrates. Before bed, you decide to have a protein shake consisting of 50 grams of whey isolate. What will happen to those 200 Calories (50 g protein x 4 calories/gram) that are now in excess, since you've already met your maintenance level of calories?
If your body has used all the protein it needs for growth, recovery, catalyzing chemical reactions, transporting molecules, and all the other physiological functions proteins are used for, the excess will be broken down into amino acids and then converted into glucose by a process called gluconeogenesis.
Once the amino acids have been converted into glucose, your body will either: a) use that glucose for immediate energy, b) store that glucose as glycogen to be used as energy at a later period, or c) store the glucose as body fat in the adipose tissue since all glycogen stores are maxed out. (The liver can store about 100 grams of glucose in the form of glycogen and the muscles can store about 500 grams.)
A study done in 2012 by Bray et al concluded that the extra calories from protein ingested by research participants were used to build new lean body mass, although all three groups gained the same amount of body fat. According to the study author, "calories alone contributed to the increase in body fat. In contrast, protein contributed to changes in lean body mass, but not to the increase in body fat." (3)
We can reasonably state that the additional protein the participants ingested was, indeed, needed for growth and recovery (shown by the increase in lean mass). However, if no additional protein was needed for these actions, the body would either use the protein as immediate energy once the amino acids were converted into glucose, store the converted glucose as glycogen for later use, or store the converted glucose in the adipose cells (fat tissue), since all glycogen stores were full.
Does the type of protein I consume matter (plant protein powder VS whey VS whole food)?
Personally, I am an advocate of whole food over protein powders. This is how I eat and how I train my clients. I only use powders for convenience or quick substitutes for the clients who have crazy schedules. I believe that the less processed something is, the better it is for your body. With that said, I'll briefly touch on the differences.
Whey protein concentrate. This is usually the most basic form of protein powder. The protein supplement labeled as a concentrate, by law, must be at least 35% to 80% protein by weight. It's a simple procedure to process a whey concentrate, which is why, most of the time, whey concentrates are the cheapest, and you get what you pay for.
Whey protein isolate. This is a purer protein powder. By law, whey isolates must be at least 90% protein by weight. The filtration process of isolates is completely up to the supplement company manufacturing the protein, but the biggest difference between concentrate and isolate is the percentage of protein per scoop. Isolates are more expensive and it's up to you to decide they are worth the money, based on the protein to calorie ratio.
Whey protein hydrolysate. This is significantly different from concentrates and isolates when it comes to processing. Hydrolysate proteins are treated with enzymes and acids to reduce particle size and eliminate the quaternary protein structures. This is why whey protein hydrolysate is the fastest digesting protein powder; the need for gastric digestion has been eliminated.
Soy protein. This type of protein is heat treated before it is sold, destroying enzymes in the soy, cleansing the powder of trypsin inhibitors. The soy isoflavones contained in the powder aren't a "huge" concern, but they can present a hormonal impact in men—by increasing estrogen. However, most of the concerns about soy are overblown.
Plant-based protein. This is the perfect choice for vegans and vegetarians. The only issue with plant-based proteins is that most are not complete protein sources, meaning they lack some of the essential amino acids. You can make up for this lack by combining it with certain other foods.
Can too much protein cause kidney stones?
As I mentioned in our previous article, excess protein can boost levels of uric acid, which has been shown to contribute to kidney stones. However, there is no evidence that elevated protein intake in healthy people will cause kidney damage.
Only when a person already has problems with their kidneys is caution needed. If you have had kidney stones before, you are more likely to get them again. Most kidney stones occur when calcium combines with either oxalate or phosphorous. I'm not a doctor, but to quote Dr. Melanie Hoenig, an assistant professor of medicine at Harvard-affiliated Beth Israel Deaconess Medical Center, some of the best ways to prevent kidney stones are:
"Drink plenty of water (drinking extra water dilutes the substances in urine that lead to stones), ensure sufficient calcium intake (too little in your diet can cause oxalate levels to rise and cause kidney stones), limit animal protein (a high-protein diet can reduce levels of citrate, the chemical in urine that helps prevent stones from forming), and avoid stone-forming foods (such as beets, chocolate, spinach, rhubarb, tea, and most nuts - which are rich in oxalate.)" (5)
Do vegetarians and vegans need more protein?
This was a great question, but I think you'll going to be surprised at how simple the answer is:
Vegans or vegetarians don't need any more protein than a person following a "meat heavy" diet. The recommended dietary allowance (RDA) is 0.8 grams of protein per kilogram of bodyweight—and that's for EVERYONE— vegans, vegetarians, and meat-eaters.
I have read recommendations that vegetarians and vegans should eat 10 percent more protein than meat-eaters, but this is based on the flawed idea that because they aren't eating animal protein the complete sources of protein—that they need more total protein.
Just because your diet doesn't consist of any meat, doesn't mean you need more protein than the person eating chicken, eggs, and red meat every day. A vegan athlete's protein needs can range from 0.36 to 0.86 grams per pound of body weight (6). The RDA is definitely on the safe side and as I mentioned in our previous article, athletes and resistance exercisers will need more total protein than the average, sedentary individual.
Total protein intake can easily be achieved while following a vegan or vegetarian diet. Nearly all beans, vegetables, grains, and nuts contain protein. Although they may not be complete sources of protein, you can combine foods, such as rice and beans, to create a complete protein meal.
I recommend that vegans and vegetarians eat a diet with a variety of unrefined grains, legumes, nuts, seeds, and vegetables so that if one of your food choices is low in amino acids, the other will make up for that deficit. Please look back at our first question of this article to determine how you should calculate your daily total protein needs.
References
Journal of Sports Sciences: Dietary Protein for Athletes: From Requirements to Optimum Adaptation
Journal of Sports Nutrition and Exercise Metabolism: A Systematic Review of Dietary Protein During Caloric Restriction in Resistance Trained Lean Athletes: A Case for Higher Intakes
Bray GA, Smith SR, de Jonge L, Xie H, Rood J, Martin CK, Most M, Brock C, Mancuso S, Redman LM: Effect of dietary protein content on weight gain, energy expenditure, and body composition during overeating: a randomized controlled trial.JAMA 2012, 307:47-55.
https://www.bornfitness.com/what-is-the-difference-between-protein-powders/
https://www.health.harvard.edu/blog/5-steps-for-preventing-kidney-stones-201310046721