The amount of protein we should consume is a nutrition issue that splits opinion.
Just how much protein do we need per day?
In truth, there is no universal answer to this question, and it depends on the individual’s lifestyle, and goals.
Based on the latest scientific research, this article will examine how many grams of protein different individuals may need.
What Is Protein?
Protein is one of the three macronutrients alongside carbohydrate and fat.
To briefly summarize; protein is a large molecular structure that contains numerous amino acids.
If we go into more detail, we can break these amino acids down into three groups:
- Essential amino acids: the body cannot make these acids, so we need to obtain them from protein-rich foods. These amino acids include histidine, isoleucine, leucine, lysine, methionine, threonine, tryptophan, phenylalanine, and valine.
- Nonessential amino acids: these are the acids that the body can make by itself. For example; alanine, aspartic acid, asparagine, glutamic acid, and serine.
- Conditionally essential amino acids: these amino acids are essential, but can usually be produced by the body providing no illness is present. These amino acids include arginine, cysteine, glycine, glutamine, proline, and tyrosine.
Why Is Protein Important?
First of all, sufficient protein intake is vital for our health, and we cannot live without it.
Protein plays several critical roles within the human body including;
- Promoting bone and skeletal health
- Optimal immune response
- The growth and repair of all cells in the body
Additionally, protein can play an important role in healthy weight loss, improving body composition, and satiation.
This is just a brief overview, and you can find a full guide on protein’s benefits in this article.
What Are the Best Sources?
Animal foods such as dairy, eggs, fish, and meat offer protein with the highest bioavailability.
Protein is also available in plant foods like beans, legumes, nuts, and fermented soy products.
For some examples of high-quality protein foods, see this guide here.
What Is the Dietary Reference Intake (DRI) For Protein?
According to the dietary reference intake, all adults should be consuming 0.80 grams of “good quality” protein per kilogram of body weight on a daily basis (1).
At the present time, this guidance has been in place for approximately 70 years.
According to the latest vital statistics, this would make the recommended protein intake 61.1 grams for the average 76-kilogram American female.
For the average 88-kilogram American male, this would work out to be 71 grams of protein per day (2).
Note: This Is a Minimum Intake
It is important to note that this figure is the minimum requirement.
In other words, it is the protein requirement necessary to support the body’s basic physiological needs and functions.
In contrast, some individuals may need substantially higher amounts of protein to meet their personal requirements. We will look at this in detail later on.
Since 0.8 grams per kilogram is the minimum recommendation, a higher amount may be optimal for the physically active.
The Elderly Have a Higher Protein Requirement
The official recommended protein intake is likely too low for the elderly.
In recent years, several research papers have looked into whether the generic protein recommendations are suitable for older adults.
Here is an overview of their findings;
- Current protein recommendations may not be suitable for older adults, and an increased protein intake provides benefits such as preserving lean body mass (6).
- The current RDA for protein intake increases the risk for sarcopenia (muscle loss) and “is inadequate to promote optimal health in older adults” (7).
- A systematic review of protein intake in healthy elderly populations found that 0.83 grams protein per kilogram is the minimum dietary protein requirement for healthy older adults. However, that long-term studies suggest between 1.2 and 1.5 grams of protein per kilogram is safe and may be beneficial (8).
- A further systematic review found that low protein intake increases frailty in the elderly. Furthermore, the findings supported the need for increasing the protein intake of older adults (9).
Even though one of these systematic reviews confirmed the current minimum requirement, this was for “healthy” adults.
With significant proportions of elderly people suffering from osteoporosis and sarcopenia (bone and muscle loss), it is likely that higher levels of protein intake would provide benefit.
Why Do the Elderly Have Greater Protein Needs?
For anyone wondering why older adults have a higher protein requirement, it is simply part of the aging process.
As we age, the rate of muscle protein synthesis (MPS) declines (10).
Put simply, this means that the amount of protein older adults can digest, absorb, and use is typically not as high as seen in younger adults.
In this case, if the amount of incoming protein is smaller than the body’s protein usage, this can increase the rate of muscle loss.
It is for these reasons that a higher protein intake is likely beneficial for the elderly.
If an individual is consuming insufficient protein over the longer-term, certain signs of deficiency may start to show.
Studies Support Increased Intake
Two recent studies on this issue found that;
- In a randomized controlled trial, healthy adults either consumed 0.8 grams protein per kg of body weight per day or 1.5 grams of protein. The results showed that whole body net protein balance was significantly higher in the participants consuming 1.5 grams of protein (11).
- Consuming 25-30 grams of protein per meal increases muscle protein synthesis, while under 20 grams of protein blunts it (12).
Also, it is worth knowing that there are additional steps we can take to increase MPS.
For example, physical exercise (especially resistance training) stimulates greater rates of muscle protein synthesis (13).
Protein Intake and Athletes
Athletes are the second group of people who can greatly benefit from a higher protein intake.
Everybody knows that protein helps with building muscle, but increased protein consumption can have further benefits for athletes.
For instance, studies show;
- Protein needs increase in energy-restricted athletes, and higher protein intake helps to preserve muscle while losing weight (14).
- Doubling protein intake from 1.2 grams per kg of body weight to 2.4 grams promotes increased lean body mass and fat loss (15).
- According to the International Society of Sports Nutrition, there is persuasive evidence that higher protein intakes (>3 grams per kg body weight) promote fat loss in athletes (16).
- Significant increases in energy from protein consumption does not appear to negatively affect body composition. Consuming 4.4 grams of protein per kg of body weight (5x the recommended amount) led to no adverse changes in resistance-trained individuals in a randomized trial (17).
While the precise protein requirement will differ depending on the sport and the intensity of training, a higher protein intake would be advantageous for many athletes.
Higher Protein Intake May Help With Weight Loss
The third group of individuals who may benefit from a diet higher in protein is people who are striving to lose weight.
Protein has a range of characteristics that lend to its potential weight loss benefits;
- Protein is the most satiating out of the three macronutrients. As a result, higher protein intakes can decrease food cravings and total daily energy intake (18).
- Interestingly, protein has a thermic effect. Our body uses more energy (hence calories) to metabolize protein compared to other macronutrients. Therefore, individuals consuming a high-protein diet have a slightly higher metabolic rate and energy expenditure, which may lead to weight loss (19, 20, 21).
- A randomized controlled trial in 118 adults compared the effects of a high-protein and standard protein diet. Overall, the study found that participants who adhered to a high-protein diet (1.34 g/kg body weight) lost significantly more weight over six months than participants adhering to a standard-protein diet (0.8 g/kg body weight) (22).
- A further randomized trial demonstrates that consuming a high-protein egg and beef breakfast (35-gram protein) leads to decreased appetite and reduced evening snacking compared to either skipping breakfast or consuming cereal (23).
Weight loss is all about consuming less energy, but that is not the full story.
The full story is whether our diet and lifestyle provide the necessary conditions to reduce our food consumption, and protein can offer a big, satiating hand with this.
Is It True That Too Much Protein Can Damage Our Organs?
Firstly, there is a misconception that high-protein intakes can damage our kidneys.
However, this is non-evidence-based, and there is no research to support the idea of protein causing damage to a healthy individual’s kidney.
On this note, a study from Dr. Jose Antonio at the International Society of Sports Nutrition found no adverse effects from following a very-high-protein diet for a period of one year.
In this particular study, participants consumed between 2.51 grams and 3.32 grams of protein, every day, for 12 months. Comprehensive testing on the participants found no negative impact on the lipid (cholesterol) profile, liver, or kidney function (24).
That said, it is possible to consume anything to excess. There will be a point of diminishing returns when adding extra protein to the diet.
However, the evidence suggests that a higher intake of protein is better than a lack of it.
For anyone unsure about the protein content of food, this guide shows the amount of protein in 230 common foods.
Protein can have lots of positive impacts on our health. Consuming this macronutrient in sufficient amounts supports satiety, body composition, and musclular and skeletal health.
Personally, as a physically active individual, I usually consume somewhere around 2 grams of protein per kilogram of body weight.
However, we are all different, and what is right for one person may not be suitable for another.
For this reason, it is always a good idea to listen to our own body and to eat, monitor, and adjust.