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Zuletzt aktualisiert am 13.09.2025
“Protein makes you sick!” – that’s what many current headlines say. The articles claim that a high protein intake is harmful to the kidneys and the body in general. But is that really true? Is too much protein harmful?
We dug deep into the topic, read numerous studies, and now give you a short summary. So: What happens with too much protein?
Your knowledge to go: What happens with too much protein?
A long-term high protein intake is controversially discussed in research!
Where exactly the limit to “too much” lies is not clear. However, an intake of up to 2 g of protein per kg of body weight is considered safe by professional societies.
More long-term studies need to be conducted so that we can know for sure what exactly happens with too much protein.
Overview – What happens with too much protein?
First, a little reassurance: If you eat a whole pack of protein bars because you just can’t stop, that’s not directly dangerous. You might get some stomach pain if your stomach is sensitive, but no long-term consequences like a protein overdose are expected. But what happens if you consume very high amounts of protein every single day over a long period of time?
Kidney overload: myth or fact?
What happens with too much protein and our kidneys? This question has been floating around the internet for years, and many studies have looked into it. Still, there are no final scientific conclusions – crazy, right?
One thing is certain: A higher protein intake means extra metabolic work for the body, including the kidneys.
So what about healthy people with healthy kidneys? Most current studies agree that a protein intake of up to 2 g / kg is safe for the kidneys. It challenges them to peak performance, but does not directly harm them. Anything above that is still a scientific gray area.
Update: Some studies suggest that high protein intake is associated with increased calcium excretion – whether this has a practical impact remains unclear.
Our tip: To support your kidneys, always drink plenty of water!
Our metabolism: type 2 diabetes & co.
What happens with too much protein and our metabolism? Some research is looking into potential links between high protein intake and metabolic parameters, but there are no clear results yet. And here’s the kicker – scientists themselves say that the underlying mechanism is not yet understood. Other metabolic disorders also fall into the category “can, but doesn’t have to.”
High protein intake and digestive issues
Stomach pain after too much protein? That can actually happen!
Some people report an unusual stomach feeling or digestive irregularities with high protein intake, which varies individually. Why is that? What happens with too much protein and digestion?
Reasons differ: You may not tolerate the protein source or its components, or you increase your protein intake suddenly and overwhelm your digestive system. But these are all short-term symptoms that should pass quickly.
Protein & our cardiovascular system
Is too much protein bad for the heart and cardiovascular system? Again – surprise – there are no solid findings yet. Research on the role of protein in cardiovascular health is contradictory, and no clear connections have been confirmed so far.
Next question: What happens with too much protein and our arteries? Some recent studies suggest there might be a connection – but they were animal or very small studies, so the results aren’t really reliable.
The liver of healthy people doesn’t mind protein
A high protein intake from animal sources is linked in studies to changes in liver metabolism. But this mostly affects older, overweight individuals who eat a lot of meat. For most of us, it’s not really relevant.
Protein and our bones
What happens with too much protein and our bones? As mentioned earlier: High protein intake may lead to more calcium excretion. Bad news for bones? Unclear.
So for now: fingers crossed and wait for more study results.
Very important: An adequate protein intake helps maintain normal bones!
So, are proteins dangerous?
Are you thinking after this summary “Okay, I’ll never eat protein again”? I get it!
But you really don’t have to be afraid of protein – that would be fatal. Protein is one of the three major macronutrients and is absolutely safe in recommended amounts.
All the scary consequences mentioned here only apply to high protein amounts above recommendations. That’s why the question is “What happens with too much protein?” or let me emphasize it differently: “What happens with too much protein?”
The safe standard recommendation for protein intake for the general population is 0.8 g of protein per kilogram of body weight (up to 2 g per kilogram of body weight for certain groups) – learn more in our article "How much protein per kg?".
You probably noticed that I kept writing possibly, maybe, potentially, and could in almost every section. Why? Because there’s hardly any solid evidence yet. Many studies are short-term or done with people who already have kidney issues. So the results are not always representative or applicable to everyone.
That means there are often no studies proving one thing or the other for sure. Something may happen, but it doesn’t have to.
It’s like saying: “You might fall off the roof tomorrow.” It could happen, but it doesn’t have to. And: The risk is low with normal behavior, but increases if you spend extreme amounts of time on the roof balancing on one leg with your eyes closed doing tricks. You get what I mean?
A reasonable approach to both roofs and protein is key.
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The role of protein powders & co.
When we talk about protein, we often think of eggs, meat, or legumes. Studies also often focus on these foods as protein sources. But what’s often overlooked: More and more people drink protein shakes and eat protein bars daily.
So what about that? What happens with too much protein from high-protein products? Can protein powders have side effects?
Some find protein shakes hard to digest or report feeling overly full – maybe you’ve also had some stomach rumbling after a shake? Exactly how protein shakes & co. affect our health still needs to be researched.
Safe handling of protein
What can you do so you don’t have to panic-Google “What happens with too much protein?!” after your 20th protein shake of the day:
As with everything in life: moderation, not excess. Stick to protein intake recommendations and don’t overdo it with protein shakes and the like.
Focus on good protein sources: They should also provide unsaturated fatty acids, vitamins, minerals, and fiber. Even with high-protein products, you can and should check the ingredients and choose high-quality products.
Pay attention to your body and possible symptoms of too much protein (like stomach pain).
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Conclusion: What happens with too much protein?
So, what happens with too much protein? Well, we don’t know exactly. There aren’t enough long-term studies showing the effects of high protein intake on our bodies. An intake of up to 2 g / kg is currently considered safe by professional societies.
Bottom line: Neither too much nor too little protein is good for us. So it’s best to stick to the recommended amount and handle products like protein shakes responsibly.
Literature
DGE (Deutsche Gesellschaft für Ernährung e.V.) (2023). Leitlinie Protein. Evidenzbasierte Leitlinie zum Einfluss von Protein auf gesundheitsbezogene Endpunkte. https://www.dge.de/
wissenschaft/dge-leitlinien/
leitlinie-proteinRaschka, C. & Ruf, S. (2017). Sport und Ernährung. Wissenschaftlich basierte Empfehlungen, Tipps und Ernährungspläne für die Praxis. 3. Auflage. Georg Thieme Verlag KG, Stuttgart.
Zhang, X., Kapoor, D., Jeong, S., et al. (2024). Identification of a leucine-mediated threshold effect governing macrophage mTOR signalling and cardiovascular risk. In: Nature Metabolism, 6(2).
Do you have questions? Then feel free to send me an email – I look forward to hearing from you! :)
The information shared in this article does not replace individual medical or nutritional advice.
