In search of the ‘gainz’ many people will constantly feed their muscles with protein, which is understandable as protein is responsible for the growth and repair of muscle within the body. However, a friend of mine recently asked me whether they can eat too much. ‘Doesn’t it cause liver or kidney damage? ‘
When we ingest protein, unlike fat and carbs, our body can only store so much. It is either used, or transformed into glucose or fat to be used for energy, or excreted in our urine. A lot of these processes go through the liver and kidney. The kidney is used for filtration and therefore has to remove waste products from protein metabolism. Many people believe and will suggest that excessive protein intake puts a lot of stress on both of these organs and can cause damage…
…However, if your liver and kidney are healthy there is no need to worry. None at all. One research study, which had subjects consume 4.4g of protein per kg of body weight per day, had ‘a few subjects’ complain of gastrointestinal distress. But if you read peer reviewed research studies there is no evidence to suggest renal damage or any sort of kidney or liver issues are associated with excessive protein intake.
In fact here is a quote from a paper in Advances in Nutrition, May 2015 –
It is also important to note that high-protein diets are harmful to CKD (chronic kidney disease) patients; however, for healthy kidney patients, in view of the findings of several studies, the consumption of a high-protein diet appears to be more advantageous than deleterious. In addition, dietary protein seems to play an important role in other metabolic processes, such as satiety, cellular signaling, and thermogenic and glycemic regulation in the body. However, this effect becomes important only when consumption is above the RDI; thus, it seems likely that protein intake above the RDI could be advantageous in many situations.
How much protein is optimal?
The study previously mentioned that had subjects consume 4.4g/kg BW also used a control group that consumed only 1.8g protein/kg BW and it was found that there were no differences between the two groups body weight and lean body mass. Irrespective of your training goals a protein intake of 1.8g/kg BW is supported by various research studies as a more than sufficient amount.
As an 80kg male I therefore only need to eat 144g of protein. In one of my last posts I broke down exactly what I would need to eat to obtain that much protein and why supplementation should be a last resort.
- Excessive protein ingestion is NOT dangerous or harmful for healthy individuals
- However, nor is it necessary to eat excessive amounts – 1.8g of protein per kg of bodyweight per day will suffice. Irrespective of your training goals.