There is quite the variety of opinions regarding the ideal amount of protein intake for human beings. Some claim that you need 1 gram per pound of body weight, others claim that people only need 10% of calories from protein (i. e. 50 grams on a 2000 calorie diet), and many recommend amounts in between these two. The USDA currently recommends that adult men and women consume .8 grams of protein daily for every 2 pounds of body weight. For example, a 140-pound person would be consuming 56 grams of daily protein if they were following the USDA’s recommendations. So with all the differing opinions, how can we know whether or not we are in-taking the correct amount, or if we need to decrease or increase the intake? Well, the answer to that question is it depends. This is because of human bio-individuality, which means that every person’s body responds differently to things, and therefore each individual has different needs. In spite of this variance, there are ways in which you can gauge how much protein you need, and I am going to help you break that down.
Who should NOT eat more protein?
When distinguishing a person’s protein needs, the first thing that should be considered are pre-existing health conditions. In the case of chronic kidney disease, a high protein diet may exacerbate the illness because protein is filtered by the kidneys. People with kidney disease or compromised renal function should limit their protein intake. Others that should consider limiting dietary protein are pregnant women because their ability to convert toxic ammonia from protein into nontoxic urea is partially compromised. One of the great things about the female body is that it is usually naturally averted to protein when pregnant. Others that may have an inability to remove ammonia from the blood are people that have a rare genetic urea cycle disorder. Unfortunately, most of these uncommon disorders are difficult to accurately test for, and therefore are often left undiagnosed.
Is protein harmful for healthy people?
For ethical reasons, there is only a limited amount of research regarding how long-term high-protein diets affect the human body. Most human studies on this topic are done on a short-term intervention, ranging from a few weeks to a few months in length. The longer ones are based on questionnaires that participants fill out based on their own memory, which can lead to false conclusions, especially if other variables are not controlled. However, there have been long-term animal studies indicating that such diets do not cause any serious adverse effects and may even be beneficial for improving markers related to metabolic syndrome, insulin resistance, and detoxification. The downside to this data is of course that it does not necessarily accurately depict the effects that such a diet would have on humans. In any case, a long-term high-protein diet does not seem NECESSARY for maintaining health, but consuming higher amounts of protein for a short time period does seem to be helpful and therapeutic in certain cases.
Reasons to increase protein intake
Generally, people naturally tend to consume as much protein as they need without having to make a conscious effort to meet their needs, at least more so than they would with carbohydrates and fats. But there are cases in which a person might want to increase their protein intake to achieve specific goals. One of these reasons is for building or preserving lean muscle mass. Studies involving strength-training individuals have indicated that consuming low amounts of protein (about .4 grams of daily protein per pound of body weight) results in a decrease in protein synthesis, which results in a decrease in muscle building and repairing, when compared to consuming moderate-to-high amounts of protein (up to 1 gram of daily protein per pound of body weight). This is especially important for individuals looking to maintain muscle mass while on a caloric deficit because of the way that energy consumption affects nitrogen balance. Generally, a positive nitrogen balance leads to muscle growth while a negative one leads to muscle loss; increasing protein intake leads to a more positive nitrogen balance. When studies compare the protein needs for maintaining a zero nitrogen balance, a higher calorie diet decreases a person’s protein requirements for muscle maintenance. For example, when all other factors are controlled, someone that eats 2000 calories per day will need to consume more TOTAL protein (not percentage) for muscle building/maintenance than someone who eats 4000 calories per day. This leads me to my next point.
Increasing protein intake may be a good idea for people who are looking to lose weight. Protein is often considered the “satiating macro-nutrient” because it tends to make people feel satisfied and filled up for longer time periods. This makes it easier for a person to maintain a caloric deficit, which is necessary for achieving weight loss. Several research studies have indicated that overweight individuals who eat higher amounts of protein, when controlling for carbohydrate consumption, tend to naturally eat less total calories per day than those who consume less protein, without counting their caloric intake. This spontaneous reduction in calories then results in a more natural weight loss that requires less “self-discipline” and “willpower,” which can then make it easier to keep weight off and can decrease the chances of developing poor relationships with food and disordered eating habits. Other studies that compare a high-protein calorie-deficit diet (≈30% protein) with a high-carbohydrate calorie-deficit diet (≈17% protein) in overweight individuals indicate that a greater amount of fat loss and a decrease in cardiovascular disease risk blood markers can be achieved with a high-protein diet (along with a calorie-deficit) more effectively than with a high-carbohydrate calorie-restricted diet, while also preserving more lean muscle mass. One study also concluded that consuming a higher protein diet (18% protein vs. 15% protein) following a weight loss period results in lower rates of weight regain and better satiety.
Because of the muscle-sparing effects of dietary protein intake, it can be very beneficial for elderly individuals. Serious injuries from falls are extremely common in this age group, especially in those that are most frail. In the presence of more muscle mass and stronger bone density, falls would likely be less common and also result in less severe injuries. When people reach a certain age, usually in their 30s, age-related muscle and bone density loss begins to occur and can result in extreme fragility in later years. Fortunately, a protein intake higher than the RDA, along with consistent resistance training, can help to slow and/or prevent muscle and bone density loss in middle-aged and elderly individuals.
Blood Sugar Management & High Stress
Another group of people that may benefit from an increase in protein intake are overweight individuals with blood sugar regulation issues and people who experience high stress levels. Studies indicate that higher protein diets result in a decrease in type 2 diabetes and cardiovascular risk markers like waist circumference, triglycerides, and LDL cholesterol levels. One study also concluded that consuming a 30%-protein diet with glucose containing foods resulted in a lower blood glucose response after meals and improved glycated hemoglobin levels, a marker for type 2 diabetes, even when weight remained unchanged. Because low blood sugar and high cortisol are associated with high stress and irritability, protein’s blood-sugar regulating effects may be beneficial for improving stress management in individuals experiencing difficult periods in their lives.
Strength & Endurance Athletic Performance
Both strength and endurance athletes can benefit from consuming more protein than the current RDA. Protein provides the raw materials needed to build and repair muscle tissue, which makes it essential for both strength and endurance athletes who are looking to maintain adequate muscle mass to continue to maximize their athletic performance. Studies suggest that athletes can benefit from in-taking up to twice as much dietary protein as the RDA, which equates to about 12%-20% of calories from protein, unless insufficient calories are being consumed (as explained earlier).
Most of these listed benefits are seen above the RDA for protein and cap at around 1 gram of protein per pound of body weight, or around 20%-35% calories from protein (particularly in a calorie-deficit diet). These higher intakes of protein have also only been studied in short term interventions (up to 6 months), and so it would be wise to increase protein intake intermittently, as opposed to using it as a lifelong dietary strategy.
Plant-based protein vs. animal protein
So let’s say that you’ve decided on an adequate protein intake for you; now you may be wondering where that protein should come from. Should you consume protein from animals or plants, or is there even a significant difference between the two? Yes, they are different in several ways. Animal proteins are referred to as “complete” proteins, and plant-based proteins are referred to as “incomplete” proteins because of their amino acid content. Animal proteins contain all the “essential” amino acids–which are histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and valine–in adequate proportions, while plant-based proteins do not. This is why it is often recommended that vegetarians combine certain plant-protein foods to prevent amino acid deficiencies/imbalances. The essential amino acids are considered as such because our bodies cannot create these amino acids, and therefore we must ingest them. This does not necessarily mean that non-essential amino acids are not important, especially when we consider the variability in our abilities to form them.
Aside from their amino acid profiles, plant proteins differ from animal proteins in that they come coupled with fibers and anti-nutrients that make them less bio-available for humans, meaning that we do not absorb them as easily. According to the Food and Agriculture Organization, based on the Digestible Indispensable Amino Acid Score (DIAAS), animal-sourced protein from foods like whole milk, beef, and eggs, are absorbed more efficiently than plant-sourced proteins including that from soy, grains, and legumes.
Another difference between plant and animal proteins is the protein density within the foods. Plant-based proteins are usually coupled with relatively high amounts of carbohydrates. For example, 1 cup of cooked quinoa provides 222 calories, 39 grams of carbohydrates, and a mere 8 grams of protein. Compare that to a quarter-pound of lean beef, which contains 170 calories, 8 grams of fat (no carbohydrates), and a whopping 23 grams of protein. And the density of protein in animal foods increases with leaner meats. So overall, while plant foods do provide protein along with other wonderful nutrients (see my post on vegetables for more info!), animal sources are much higher in protein density and are more easily absorbed.
What about protein powder?
Aside from whole foods, there are so many protein supplements being sold and promoted in the health and fitness industries, so you may be wondering whether or not these are necessary for you to consume. Well, the answer to that really depends on your individual protein needs. It is always preferable to source your protein from whole foods (and this is usually true for any nutrient), but there are times when you may find yourself struggling to meet your protein requirements from these foods. Perhaps you’re aiming at consuming 120 grams of protein per day but find that within your three meals, you end up short of 20 or so grams. In this case, you may benefit from taking a protein supplement as snack or with a meal. Even then, it is important to consider the type and quality of your protein supplement. Lots of supplements on the market are high in sugar and other ingredients that are unnecessary and may cause digestive upsets, so it is important that consumers read the ingredients lists of protein powders before purchasing them. Also, many people tend to be intolerant to whey and casein protein, so you will have to do a bit of trial-and-error work to see which supplement you digest best. Overall, it is always best that your animal protein supplements come from grass-fed cows, pasture-raised chickens, etc. If you find that you do not do well with whey, casein, beef, nor egg white protein isolates,–and still want to consume a protein supplement–then you may want to consider a plant-based protein powder as a last resort.
So overall, if you eat animal protein frequently with your meals, feel well on your current protein intake, and you don’t have any goals or concerns dealing with the issues mentioned above, then it is likely that you do not need to worry about upping your dosage. Contrarily, some people may benefit from increasing their protein intake, but the amount that is necessary to reap these benefits is not all that high, in my opinion. For most people, it may be quite easy to reach there needs with whole foods, but others might need a bit of help from a high-quality supplement. Additionally, because there is a shortage of experimental studies regarding long-term high-protein diets, it would be much wiser to increase protein intake temporarily for certain time periods, and then gradually decrease it once certain goals or needs have been met, and assess your health and nutrition markers throughout the process.
I hope you enjoyed and found this information helpful. If you have any further questions or concerns about this topic, or if you just want to share your appreciation, feel free to leave a comment below!
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