Amid the recent fitness craze for building muscle, a growing number of people are consuming excessive amounts of protein. However, experts agree that protein is not a nutrient that is always beneficial when consumed in large quantities. They point out that not only the amount but also the source of protein must be considered.
"What You Eat Matters More Than How Much"
According to a study recently published in the Journal of Nutrition, an international nutrition journal, excessive intake of animal protein is associated with an increased risk of chronic kidney disease (CKD). In particular, diets centered on red meat showed a clear correlation with declining kidney function. The findings suggest that the type of protein has a greater impact on health than the quantity.
In contrast, plant-based proteins such as legumes and grains were relatively safe, with some even showing a tendency to lower CKD risk. Protein from fish and seafood was also found to have a protective effect, reducing the risk of kidney disease by 14 to 23 percent.
"Protein is an essential nutrient, but its health effects vary depending on the source," the researchers said. "Those at risk of kidney disease, in particular, need to consider the quality of their protein."
"Excess Protein Can Be Toxic"…Burden on Liver and Kidneys
Choi Seok-jae, a professor of emergency medicine at Yeouido St. Mary's Hospital, also said on a recent YouTube channel that "there is a fantasy about protein." He explained, "The amount our body needs is fixed, and exceeding that amount can actually be harmful."
Unlike carbohydrates or fats, protein contains nitrogen, which can act as a toxic substance in the body when consumed in excess. In fact, consuming too much protein can prolong digestion time and cause abdominal bloating, diarrhea and indigestion, and may also lead to constipation when dietary fiber is insufficient.
In addition, an increase in nitrogen waste products such as ammonia and uric acid, which are generated during protein breakdown, can burden the kidneys and lead to elevated liver enzyme levels or fatty liver. The risk is particularly greater for those with weak liver function or those who drink alcohol at the same time.
"Some people consume excessive amounts of protein shakes or eat 20 to 30 egg whites a day," Choi said. "Being young does not automatically make it safe."
Proper Amount Is Based on Body Weight…Spreading Intake Is Key
So how much protein is appropriate?
Experts recommend 0.8 to 1.2 grams per kilogram of body weight for average adults. For example, a person weighing 60 kilograms should consume about 48 to 72 grams per day. It is also advisable to get 7 to 20 percent of daily calorie intake from protein.
What matters is "not eating it all at once." Spreading protein intake across meals is more efficient in terms of how the body utilizes it.
Protein shakes also require caution. Some products have high sugar content, making them virtually ultra-processed foods, so checking the ingredient list is essential.
In the end, although protein is an important nutrient for building muscle, experts agree that consuming "an appropriate amount from good sources in a balanced way" matters more than simply "eating a lot."
