How much protein is enough, what happens if you have a deficiency we lack it, and what if you overdo protein supplementation? Protein is a popular nutrient found in many foods, yet many people feel the need to supplement their daily diet with it. We've already clarified what proteins are, what they consist of, and where they come from. Now, let's dive a bit into the math. That is, let's talk about how much protein consumption is ideal.
What Determines Daily Protein Needs?
To accurately determine or estimate the exact grams, it's important to emphasize that many factors influence how well our bodies function with a certain amount of protein.
Our protein needs are not a constant factor in our lives; they depend, among other things, on our age, health status (certain forms of kidney disease, and liver disease can significantly disrupt this), lifestyle (e.g., how much we work our muscles), but also on pregnancy and lactation, which influence it (spoiler: they increase it a bit).
What's the Average Daily Protein Requirement?
In the case of an average adult, 10-15% of the ideal energy consumed in the diet comes from proteins. The role of proteins is not to provide energy to the body; that's primarily the job of carbohydrates and fats. However, in case of emergency, we can derive some energy from proteins too. Nevertheless, this latter method is not the most efficient for the body, so it's not worth experimenting with it.
The consumed proteins should come from plant and animal sources in about a 50-50% ratio in a balanced, mixed (omnivorous) diet. From a sustainability perspective, we can shift this ratio somewhat towards plant-based proteins, but to ensure adequate amino acid supply, we don't have to give up animal protein sources. As usual, the emphasis here, as in most things, is on the balance.
In numerical terms, for an average-sized, healthy adult, it's recommended to consume approximately 0.8-1 gram of protein per kilogram of body weight per day. This amounts to 56-70 grams per day for a 70 kg adult. (Body weight in kilograms is calculated based on the ideal body weight corresponding to the individual's physique.)
The physiological minimum for protein is 40 grams per day, meaning this much is necessary for basic bodily functions, without doing anything (like exercising or working). It's not difficult to consume this amount, although if a special, low-protein diet is the goal (e.g., in case of chronic kidney disease), then it's important to be very careful to fit within this limit.
For this reason alone, it's worth getting our kidneys checked regularly so that if any value (based on blood test results or urine analysis) deviates from the norm, we can intervene in time (to avoid, for example, dialysis).
If we delve a bit deeper, we can refine the topic:
Compared to adults, children (over 3 months of age) need relatively more protein because they are still growing and developing. So, their target is 1.3-1.8 grams per kilogram of body weight.
Athletes form a separate group, and by this, I don't mean those who go for a run, swim, or bike ride once or twice a week, but those who engage in more intense sports. Their protein needs vary from 1.2 grams to as much as 2-2.5 grams per kilogram of body weight, depending on the sport and the intensity, frequency, and duration of the workouts (the point is: it's not several times that of inactive individuals). The extra protein serves to compensate for the increased protein breakdown due to exercise and to ensure muscle recovery after exercise. For competitive athletes, and elite athletes, a sports doctor, or a sports (specific) dietitian becomes involved in determining the individual's needs. Therefore, this is just a general guideline. Returning to our 70 kg subject, their daily protein requirement can range from 84 to 175 grams (calculated with multipliers of 1.2 and 2.5). To reach 175 grams, one would have to make a real effort in terms of eating (supplementation might be necessary at this point), but consuming 84 grams or a similar amount is achievable with a normal diet.
Older individuals are advised to consume proportionally more and higher-quality protein to maintain muscle mass, as their digestion efficiency declines and breakdown processes become more prevalent.
In cases of infection, sepsis, acute illness, or post-surgery recovery, protein requirements also increase (up to 1.5-2 grams per kilogram of body weight).
Pregnancy increases the daily protein requirement by about 10 grams. This can be easily achieved with a small additional meal.
What Happens If You Eat Too Little Protein?
Protein deficiency can occur primarily during starvation, fasting, or due to with poorly or unilaterally composed diets. In childhood, it can lead to stunted growth and development, as well as digestive and hormonal problems, the appearance of edemas (especially in the legs and abdomen), anemia, fatty liver, and weakened immune system, resulting in more frequent infections and illnesses.
In the past, there was much criticism of vegetarian and vegan diets for not providing enough protein to the body. Today, it is well known that not only animal-derived foods (e.g., meats, fish, eggs, milk) contain protein but also legumes, nuts, and grains do. With proper combinations, attention, and consciousness, mostly plant-based or completely plant-based diets can also meet the protein requirement, but this requires some expertise and background information on the typical composition of foods and raw materials.
What Happens If You Eat Too Much Protein?
Extra protein intake over a long period of time challenges the kidney's excretory function, but it can cause problems primarily if there is already some underlying or known kidney issue. The problem is that it may take a long time for kidney involvement to become apparent, and problems may manifest late (such as changes in urine volume). Excessive protein intake has been associated with the development of certain joint diseases and liver damage (especially if high intake is combined with proteins, which is quite common in diets like keto or paleo). Other discomforts may include disturbing body odor, bad breath, and digestive problems (bloating, nausea, vomiting, diarrhea). For these reasons, it's worth considering whether it's necessary to boost the diet with protein shakes, which are already protein-rich by default (e.g. if we eat meat, cold cuts, and meat products several times a day). Of course, it also matters what makes up the extra protein, but here we focused only on the net quantity.
When Is Protein Supplementation Justified?
The above example in grams showed that an average-weight, physically active (say, sedentary) individual does not require hundreds of grams of protein daily. If someone competes in sports and engages in mainly muscle-strength demanding sports, and therefore has a higher protein requirement, but finds it difficult to meet it with a normal diet (because, for example, they don't have time to eat so much due to frequent workouts), then this justifies the consumption of various protein-rich powders, bars, and other supplements. However, these only supplement, not replace, a consciously and well-constructed diet. They provide a little crutch but it's not advisable to overdo them either, as they too have the side effects shown just now.
In summary, this is an interesting and complex topic that we've only scratched the surface of here. Too little is not enough, too much is not better - this saying holds true here as well.
If you'd like to find out how much protein you need and how you can consume it within a delicious, easily prepared, and realistic diet, then I recommend seeking assistance from a dietitian.
Judit Schmidt dietitian, health educator, workplace well-being program manager. Engaged in prevention, education, and background work related to health, well-being, and nutrition. Provides assistance in conveying knowledge on nutrition, health, and well-being through article writing, blogging, editing, proofreading, and creating professional texts on these topics. Also conducts informative presentations for companies and schools. Her main focus is on disease prevention and creating a balanced and sustainable diet. Her motto: the sunny side of food. Dietitian Judit Schmidt presents her profession and works in a personal, occasionally humorous style on various social media platforms under the name Youteefool.
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