Leah:

Hello and welcome to the Ideal Nutrition Podcast. I am Leah Higl and I’m here with my co-host Aidan Muir and today we’ll be answering the question, are there downsides to eating too much protein? Giving a little context, obviously protein is essential for things like muscle growth, recovery, overall health, but is there such thing as too much protein?

While many people are focused on maximising protein intake, there is a point where it makes sense to potentially focus on the other macronutrients for other potential benefits. Like when it comes to muscle growth, for example, like we know we have these kinds of standard targets for where it is optimised and going like well beyond those targets. It’s like, well, okay, what are the upsides of doing that? don’t know. Maybe if you enjoy eating like that, that makes sense to do. But at least today, we’re going to go over, like, are there any potential downsides to going kind of above those recommendations.

Aidan:

I was just looking through our outline and realised I didn’t write anything about kidney health in there. Just because I feel like we’ve done it to death. We really have talked about kidneys and proteins so much. Do we talk about this today or do we move faster? Do we just ignore it?

Leah:

I guess from, okay, let’s just, I guess summarise that in that if you have healthy working kidneys, having a high intake of protein doesn’t seem to be an issue. Even looking at like super high intakes, like three grams per kilo body weight, doesn’t seem to be an issue. If you have chronic kidney disease or only a single kidney or just not for perfectly functioning kidneys, there’s probably some value in being mindful of that.

Aidan:

Cool.

Leah:

Does that summarize it?

Aidan:

Well, got some, Okay. I just did not want to ignore that. Moving on. Let’s go into the next one. This is the main one that I really want to cover today. So, missing out on the opportunity to get in other macronutrients and the benefits of those. So I’m gonna obviously talk about both of the other main macronutrients, carbs and fats.

Aidan:

I’m gonna start with fats. So if you went super low in terms of your fat intake, this could have hormonal implications because we know protein contains calories. By definition, if you ate the same total amount of calories, you’d have to be eating less carbs and or fat. So we also know there are other health benefits or other just general benefits as well to certain types of fats. Example, we consistently see benefits from things like extra virgin olive oil, nuts, salmon, avocado, heaps of health benefits, but maybe even some performance benefits in certain aspects as well.

The other one is obviously carbohydrates. So it reduces how much room you have for carbs. We know that carbs are the best fuel source for exercise. That’s not a controversial thing to say, but it also reduces the room you have for high-fibre carb sources. This has implications for gut health and other things as well. Even if we’re looking at chronic health outcomes and stuff like that, if you chart fibre intake and chronic health outcomes, like usually increasing fibre is typically a good thing for these things. And there are many micronutrient-rich carb sources and fat sources I should also mention, but there are many micronutrient-rich sources that would be displaced by this approach of really pushing protein.

Doubling down on that calorie content thing, like stating the obvious, protein still contains calories, it contains four calories per gram. We don’t need to spend much time on this aspect, but I talked about it through the lens of what if you kept calories stable? But if you just aim to have as much protein as you could eat, like potentially that contributes to raising your total calorie intake, which would come with other issues as well. So the main thing though is it contains calories and it also could mean that you’re missing out on the opportunity of getting in other macronutrients and the benefits.

Leah:

Yeah, and protein is also known as the most satiating macronutrient, at least per calorie. For some people, that’s going to be a pro. I think there are times where it could be a con though, particularly if you have a really high protein intake and that’s very satiating and then you struggled to get enough calories in to meet your overall needs. It might make sense to bring that protein intake down a little bit if it’s already kind of like beyond the general recommendations for what your specific goals are. So I think even from that point of view, it makes sense to be like, well, like, let’s just dial this back so that we can actually allow for adequate calorie intake.

Aidan:

Let’s talk about taste and dietary flexibility. In my life, I can only name a few people that have ever claimed that protein is their favourite macronutrient from a taste perspective.

Leah:

Liars.

Aidan:

Have you met many people? Have you had anyone say this?

Leah:

I only maybe one or two bodybuilders.

Aidan:

But yeah and same as you, the people who I’ve heard it from are bodybuilders. Every single one I’ve heard it from, not that there’s that many, who have quite a warped perception of food. I just don’t believe that that’s their favuorite macronutrient. I do believe that some people listening to this might kind of challenge me and be like, I like the taste of steak. And I’m like, I’m not challenging that.

I’m just saying as a macronutrient individually, most people would have a preference for other macronutrients from a purely taste perspective. And just to like double down that, you forgot everything, if you forgot everything you knew about nutrition, you would never make the claim that protein is your favorite macronutrient. By avoiding going significantly higher in protein than you need to absolutely maximise muscle growth, you can be so much more flexible with food while also getting the same body composition and performance results, if not better in certain cases.

Leah:

Coming at this from a gut health perspective, there is research indicating that high protein diets are linked to poorer gut health and a less diverse gut microbiome. But honestly, looking at the totality of the research, I’m not overly concerned by this because it does seem that when you have a high enough fiber intake, it pretty much cancels out the negative consequences that can come along with having a really high protein diet. So I guess if we’re looking at high protein carnivore diet with very little fiber intake. Okay, yeah, that’s going to be not great for gut health. But once we have that adequate fibre in there, we’re pretty good.

I would say though that going really high protein does like, like really, really high, reduces the odds of you achieving a good like protein to fibre ratio where we are actually offsetting those negative side effects of the protein breakdown in the gastrointestinal system and everything that means for the gut microbiome. So again, I think it’s worth reducing to a point where you’re actually able to still get in all of those gut-friendly, gut-healthy foods and fibre.

Aidan:

I am going to talk about longevity now. And there’s a little bit of a paradox in a way in that we see that research very consistently finds increasing protein intake later in life has a bunch of benefits. That’s pretty clear-cut. We see that in research. I’ll probably come back to that. There is also very clear, what I guess I’ll call observational evidence that there are many populations that live longer lives on average that also have lower than average protein intakes. I don’t think either of those two things should be ignored, which is part of why I call it a bit of a paradox that both of those things exist.

I’m not using that as an argument for low-protein diets. I’m more just saying that common themes occur when you study diets of people who have longer than average lifespans and on average they have lower protein intakes. There could be so many mechanisms to explain this. And also the source of protein obviously influences this a fair bit too. And their overall dietary pattern and all the other things that they’re doing play a role. We’ve touched on this previously as well, but with the many benefits that people typically see later in life by adding

more protein into their diet. A lot of it does stem from increasing muscle mass, so improving body composition, having more muscle mass, which then has a carryover effect on so many things like it reduces falls, risk and a bunch of other things. If somebody has a fall, does it then reduce their ability to stay active? There’s so many things that happen there. You could also talk about bone marrow density here as well.

If you take another angle, and this is an angle I’ve heard a lot of people point to in the lower protein kind of community in a way. Staying active is so much more important than this. If you have a stimulus of exercise consistently, you will also have more muscle mass, stronger bones and all those things, even with a little bit below average protein intake. And I think that’s just a worthwhile thing, being like the average person of a certain age isn’t super active.

So there is a relatively low bar to like get over in terms of just remaining relatively active puts you well above average in terms of how much muscle mass you would have in that same category and you would be reaping a lot of these benefits regardless. So a complex topic from the longevity perspective and I think it just makes sense to be aware of both like protein later in life typically good but also being aware that people can live long lives with a relatively low protein intake as well and that’s probably a slightly more common theme out of anything as well.

Leah:

The next two things we’re going to talk about are not necessarily nutrition-based, but I think very much worth putting in here is like things that you may want to factor in if you are looking at having a very, very high protein diet. The first is the environmental impact. So someone who follows a plant-based diet for also environmental reasons amongst other things, like this is something that’s close to my heart. We know that animal sources of protein do take a lot of natural resources to produce.

So they do have a pretty large environmental impact, particularly when consumed in really high amounts in a population. So if it’s something that you care about, I would say it’s worth probably not overshooting that protein goal too much or even shifting from less animal sources to more plant-based sources. But again, it’s just something to kind of throw in here.

Aidan:

Early-ish in my days of working with clients. That was something that stood out to me just being like, I don’t personally take a lot of responsibility in terms of recommendations I make in terms of diet and environment. I kind of see my role a bit separate, but there are some clients I’ve come across who like there’s quite a few in the powerlifting and strongman space who are having well over a kilo of red meat per day. We can talk about the health implications and stuff like that. That’s the first thing that comes out being like, this person could get exactly the same results. Exactly. Without having that impact as well.

Leah:

Yeah. I think it’s an interesting thing to talk about. Cause I guess from my point of view, I feel like we all have a little bit of a personal responsibility to be mindful of these things for long-term food security for like the entire population. But it’s also something that some people just don’t care about and that, that is what it is. Personal choice. Yeah. I’ve had a very many years ago, a plant-based dietitian messaged me the same thing being like, it’s every dietitian’s responsibility.

Leah:

And I like, I don’t have as much of a hard and fast opinion on that.

Aidan:

It’s interesting because it’s like, I care about climate change, but I also don’t do that for work. There’s many things I care about that I don’t do for work.

Leah:

It’s a tricky grey area for us as health professionals to be honest.

Aidan:

Yeah. Different topic, but it is interesting. And like, I still think it’s relevant. Like when we’re talking about this being like, if you get exactly the same results without this impact, like maybe it’s worth doing. Now, another factor, once again, not nutrition, but cost. Protein is typically the most expensive macronutrient.

Let’s go back to that example of somebody having over a kilo of red meat. How much does that cost versus the alternative of just getting the ideal amount of protein and maybe a little bit more on top of that. And then having other macronutrients too. Like there’s so many, you could even get that amount of protein way cheaper than red meat, but that’s another thing. So having significantly more protein than you need is more expensive.

It may or may not be relevant to you. Like there’s many people that that just wouldn’t be an issue, right? But there’s also many people who that is kind of the barrier and they’re trying to strive for a target that’s way higher than they need to. And they feel like that is a challenge.

Leah:

Yeah. And I feel like very relevant to the kind of cost of living crisis that we’ve got going on in 2024 too. It’s like something that a lot of people are considering and trying to get their grocery bills down.

Aidan:

Yeah.

Leah:

So as a bit of a summary, overall it is fine to go well above the necessary amount of are protein to optimize muscle growth. The caveat there is if you have an underlying health condition in which this would not be appropriate, like chronic kidney disease or something like that.

But outside of that like in many cases we like to go a bit above what is required in terms of what is going to optimize muscle growth since that will ensure people do consistently hit their needs every day. So even when I’m working with clients I might set their protein a little bit higher than what is actually needed just to make sure we’re definitely ticking that box without going like wildly above those recommendations.

But like I said, we typically wouldn’t recommend going heaps above that kind of standard 1.6 to 2.2 grams per kilo body weight per day recommendation because of the potential side effects or potential detriments that would come alongside, but that’s gonna be individual to you as a person and you still might be able to go really high protein without having any of these detrimental aspects.

Aidan:

This has been episode 178. I personally haven’t read the reviews for a little while, but when I last checked, everything was pretty positive, which is good. All five stars. As always, if you want to leave five stars, we massively appreciate that. Good feedback in public. If you have negative feedback, DM, please. Thank you. Well, much appreciated to everyone who has been listening.