Protein-Maxxing: Is It Actually Bad For Us?

0:00I have a confession to make. I, um, I am a**hole. Whoa, I would never have thought I'd see the day. Hi, I'm Wendy Zukerman and this is Science Versus.

0:23these days protein is everywhere it's being added to all kinds of foods from lattes to popcorn cottage cheese is flying off the shelves and people are telling pollsters yes i am actively trying to get more protein into my diet and some of us are going hard they are protein maxing High protein talkers. High protein enchilada pasta. Five reasons why protein is essential and why eat more of it. Helps us build muscle. Helps to control our hunger. Helps to maintain a lean physique. And makes us look sexy as f***. High protein, low calorie, beef teriyaki summer rolls. We still need more protein. But just recently, we've been hearing something that is turning all of this on its head.

1:13that suggests we are doing protein all wrong. Headlines are saying that we need to actually cut back on protein if we want to live long and healthy lives. New research is challenging the high protein craze. Decades of data, animal studies and human studies, asking the question whether eating less protein can promote healthier aging and help to extend your lifespan. Low protein diets actually help you live longer. So what is going on here? Should we be protein maxing or protein minning? When it comes to protein, there's a lot of... We still need more protein. But then there's science.

1:54And if you have a friend who is guzzling down protein or just confused about what's the right thing to do here, understandably, share them this episode. We're on YouTube or wherever you get your podcasts.

2:13This episode is brought to you by ADT. One second, you're enjoying your day off. The next, your phone buzzes. A window's been broken at home. You're miles away. In one second, everything can change. That's why ADT security systems can monitor your home 24-7. They're backed by the most company-operated monitoring centers in the industry, so you're always supported during an emergency. When every second counts, count on ADT. Visit ADT.com to learn more.

3:08sally.com slash go parents.

3:19Welcome back. Today we are digging into the science on protein. And who else to give us that science but meathead senior producer, Rose Rimler. Hi, Wendy. Hello. I have a confession to make. You're protein maxing? Right now? As we speak somehow? I am adding protein powder to my yogurt. Whoa, I would never have thought I'd see the day. Trying to build more muscle. And I got sucked in. But now these headlines say, stop doing that. Rose, I'm being vulnerable with you now. I can't believe you share something so personal. Thank you. I really appreciate that. You're not alone. That's not really that special of a confession.

4:15I think a lot of people are doing that, which is why it was very surprising to crack open the internet one day and see that now everybody's talking about maybe we should be doing less with protein instead of more. Yes. Yeah. I was so surprised when I'm getting these videos saying, new study finds protein restriction is the way to go. So is the protein pendulum swinging? That's the question. And a lot of the headlines that are talking about this are referring to this one new paper that came out recently. It's all about protein and lifespan. And I talked to one of the authors. His name is Dudley Lamming.

4:56I'm a professor of medicine at the University of Wisconsin-Madison, and I'm an aging biologist. Not as in the creaks and pains of old age are catching up with him. Yeah, I'm an aging podcaster. He studies aging. I've been studying aging for about 20, 25 years now. This is exciting, though, because he is patient zero. He's the author that launched a thousand headlines about how protein restriction is healthy. Yeah, I mean, kind of accidentally. I mean, that wasn't Dudley's intention when he wrote the paper. I was quite surprised. You know, it was originally written as an article, you know, for scientists by scientists.

5:42And so it was really interesting that it got so much attention. Because it turns out that scientists like Dudley have actually been studying protein restriction for a long time. I had never heard of it, but I was in the dark. This has been around for a while. And actually, where this all comes from is, you know how there are studies in animals that find that calorie restriction can extend lifespan? Yes, yes, of course. This is fasting. People might. Fasting diets that are also very popular right now. All that research started off with animals. these exciting weird studies in animals, the little animals, the worms, the flies, they would put them on fasting diets and realize what they were living longer.

6:23Yeah. So they have basically been doing the same thing with protein restriction all this time, scientists. More or less, yeah, because fasting or calorie restriction is pretty hard to stick to. So the idea here is like, well, actually, if we're seeing some of the same benefits from not reducing your overall energy intake, but just tweaking your macros so you eat less protein, then maybe this would be a lot easier for people to actually stick to. And do they find that? That in animals, if you restrict protein, they live longer? Yeah. Short answer, yeah. I mean, in a lot of organisms, mice and rats primarily, but they've also tested it in fruit flies and yeast.

7:06I don't know why you looked at me like that and said yeast. Do you know something I don't know? I'm just really trying to avoid saying animals like yeast. Because it's not an animal. Because it's not an animal. What is it? It's a fungus. It's a fungus. And in these experiments, what scientists are doing is they're typically cutting the protein in the diets of these creatures like in half. And then increasing either the fats or the carbs. So that overall they're eating the same number of calories. And in mice, Dudley says that they live… Up to 30 % longer on a protein-restricted diet. Depending on exactly the conditions, it can be anywhere from 10 % to 30%.

7:47You can see why that's exciting. Because if that translated perfectly to humans, that would be an extra 20 years on our lifespan. Yeah, for sure. If that translated to humans. Right. And so back to this big study that got everyone all Twitter. Yes. It's not a new experiment that Dudley published. It's a review paper. Do you know, I still rose after all these years. I see the headline, new study shows protein restriction helps you live longer. And in my head, I'm like, wow, they did a study in 40 ,000 people and they followed them. And they found that those who didn't eat a lot of protein lived longer.

8:33and every freaking time you go to the paper, it's either a review paper looking at old studies or it's some research in rats. Yeah, you sweet summer child. When will you learn? But in some ways, depending on the review paper, this might be even more exciting, right? Because they're pooling together all of this research that we have from the past. Yeah. We're talking about a collector body of work, but depends any of the bodies in this study humans. There are some human bodies in this review paper. Obviously, there are no studies where scientists took, you know, 100 human babies, randomized them to either low protein or more protein and then followed them for 100 years and saw which baby lived longer, right?

9:21Uh-huh, yeah. But we do have studies where they put people on low-protein diets for kind of a few weeks to a few months and seeing what happens to them. They can measure certain things about them. So one that Dudley did, they got about 40 people. These were all men. They were overweight. These guys were randomized to either go on a low-protein diet or stay on their typical diet, which was higher than protein. The guys in the control arm, they live life as usual, while the guys in the low-protein arm— We found that they lost about a pound and a half a week, and their blood glucose went down by about 5%.

10:03Were they—the two groups eating the same amount of calories? It's just that the protein restriction group ate less protein? No. Here's the crazy thing. They were actually eating more calories than they had been before, and they still lost weight. So what does Dudley think is happening here? Okay, so here's what we know. So we know that when you feed people a low-protein diet, they make more of this particular hormone. And that hormone seems to have something to do with brown fat. Are you familiar with brown fat? Ah, there's two different cutters. White fat, brown fat. Brown fat. Tell me more. Why do we care about brown fat?

10:46So brown fat is when you end up with a lot more mitochondria in your fat. Mitochondria are powerhouse of the cell. They create ATP, fuel energy for the body to use. Yeah, so what does that mean for this brown fat if it's got more mitochondria in it? Well, if your white fat starts recruiting more mitochondria, which are a little bit brown in color, that turns the fat from white to brown in a process that scientists very cleverly call beijing. Causing them to essentially start producing more energy in the form of heat. And so the mice literally burn off additional calories as fuel and overall lose weight.

11:29Oh, okay. So you restrict protein in your diet or the mice restrict protein in their diet. They produce a hormone. And what's this hormone called? It's called FGF 21. FGF. Okay, I understand why you didn't name check it. It's not one of the cool hormones. No. But it is cool because, so to summarize, what Dudley thinks is happening, one of the reasons why he thinks protein restriction might be healthy is because when you restrict how much protein you eat or when they do it with mice in a lab, you see an increase in that hormone. and then that starts recruiting mitochondria into your white fat, turning it into brown fat, and that increases the amount of energy in that fat, increasing the amount of heat, ultimately increasing the metabolism.

12:28That's what we think. I mean, not all of those steps have been shown in humans. But I will say, I will say, there's still more reason to be excited about protein restriction. There's this whole other thing that has to do with mTOR. Do you know what mTOR is? Are you familiar with that? Yes. This is big in the longevity community. Yep. They're always trying to hack mTOR. Yeah. Yeah. So walk us through. Tell us what's mTOR. mTOR is an enzyme that coordinates cell metabolism. And the thing about mTOR is that it's kind of like a switch. When it's on, it tells cells to grow. and that seems to be linked to aging.

13:11And when it's off, it seems to increase what's called autophagy. And Wendy, you know all about this, right? From an old episode. I mean, it's one of my favorite processes in the body. And it is a way that your body replaces damaged cell parts. And what happens is that a cell will literally eat itself. That's what autophagy means. So to take this back to protein restriction, what are they finding? It boosts autophagy? It looks like protein restriction, at least in mice, tamps down mTOR, boosts autophagy. And that might be what's leading to this increased lifespan, at least in these animal studies.

14:01But then there's something inside me that still can't believe that restricting your protein is a good idea because have I just been sold a lie? I mean, we need protein, right? For muscles, for balance. It's super important. Yeah, not all scientists are hopping on board the protein restriction train. And there actually could be a downside here. It could be dangerous to try to do protein minning. Coming up next.

14:37Hey Chicago, class it up with Crocs. You know back to school is coming in fast. So why wait to find your new fave footwear? Step into a local Crocs store and step into your new look. Try it, style it, make it yours. Because the right pair doesn't just show up, it shows off. First day fits, handled. Walk out ready for whatever's next. Visit your nearest Croc store today.

15:30slash podcast. Terms and conditions apply. Need a hiring hero? This is a job for Indeed Sponsored Jobs. Saying how you feel out loud is terrifying, but that's what Hinge's new free audiobook, No Ordinary Love, is all about. It's a collection of real love stories about five couples that met on Hinge. The stories are written and read by Tembi Dinton Hurst, Nicola Dinan, Curtis Garner, Raven Smith and Rufy Thorpe. I, Hunter Harris, wrote and read the foreword. The audiobook's out now. Give it a listen.

16:27Elected by the customer. Availability, amount of discounts and savings, and eligibility vary by state.

16:41Welcome back. Today we're talking all about protein. If you have a friend slamming down the protein day after day, maybe send them this episode. rose rimler senior producer at science versus you promised me some more science on this protein restriction saying that perhaps it's not good and we can keep our protein powder well where do we go from here okay so this idea of getting really low protein is so different from what we've been hearing that i had to talk to other scientists for other perspectives the first person i thought of was Stuart Phillips. He is an exercise physiologist at McMaster University in Canada.

17:24Stuart is not on team protein maxing. So right off the bat, I'll tell you that. In fact, last year, he actually wrote a piece saying that this whole protein craze has gotten so out of hand. And he actually titled that piece, 2025 was the year that protein jumped the shark, an expression that kind of got him roasted by his family. My son was like, what is this shark thing? And I was like, well, there's this guy, his name is Arthur Fonzarelli, and he was the Fonz, and he once jumped over a shark. And he was like, what are you talking about? So what does that mean? I was like, well, it was where the show really went downhill.

18:00And he was like, that doesn't make any sense. But it's very prescient, because in 2025, he predicts that protein is all going to go downhill hill from there, much like happy days. And here we are in 2026, headlines saying we've gone too far. Yeah. So is it, but he said he's not on team. He's not on team protein maxing, but he's not on team protein minning either. So even though he thinks we've gone a little overboard with our protein, he doesn't like those headlines that came out recently about how we all need to cut back and restrict our protein. And we ran some of those. Okay, why not? Yeah, we ran some of those headlines by him.

18:41Surprising new study links low-protein diets to healthy aging. Eating less protein can help you live longer. What do you think? Yeah. Well, all of the titles you read would have been, reduced protein helps you live longer, comma, if you're a fruit fly or a mouse. But you didn't, there was some human studies, right? There's at least that one that you told me about. Yeah. I mean, Stewart's issue with that study was that it was short. And not, you know, you can't really extrapolate from like a 12-week study to what's going to happen over an entire lifetime. You know, 12 weeks out of a year that has 52 weeks out of a life that is 84 years, you know, you can do the percentage.

19:26Another problem with the study, the menus of the people, you know, in the study were pretty different. So on the protein-restricted arm, they were eating like a Mediterranean-style diet, lots of fish and leafy greens, whereas the other diet was like ribs and hot dogs and hamburgers. So there's a lot different about that diet than just the protein content. And then they found all these benefits. Yeah, and the benefits aren't too surprising. The calorie thing and losing weight is surprising. But like the other stuff, like that would be better for you in all these other ways is not surprising. Given that they're eating a much healthier diet, even if you forget about how much protein they're eating.

20:06Yeah. That's reason to be skeptical. Okay, so we don't have many human trials really putting this to the test. We don't have long-term studies, true for many things. Okay, but I guess you promised danger. Yeah. That's why we call you Rose Danger Rimler. Well, one of the reasons that Stuart is as skeptical as he is is because there's reason to believe that going quite low in protein could be bad for you. Because as we age, we get worse and worse at incorporating the protein that we eat into our muscles, and we lose muscle mass. And so for older people, and these are the people who are probably like thinking about like, how can I extend my lifespan?

20:53They're the exact group of people who probably shouldn't be going low in protein. I think that those folks are going to be in trouble. So they will lose muscle. They will get weaker. Their risk for frailty goes up. And that's where my mom is right now. So I care about my mom. If you cut down your protein and you're not getting enough to replenish your muscles, you could end up with something that's called sarcopenia, which is like not having enough muscle mass and being really frail. So this is what we've known for a while. Protein is important for building muscle. So you need to get enough of it.

21:32Yeah. And if you don't, I mean, the sarcopenia thing, it is a pretty big deal. Like we know that people who have sarcopenia, they are more likely to have falls. They're less likely to be able to be independent, you know, like eat, get dressed, go to the bathroom by themselves. And they're more likely to die like four times more likely compared to people their age who don't have sarcopenia, according to one review. And it's not only that, though. Like, there's this whole other thing we have to think about when it comes to low-protein diets. It could really mess with your immune system. And this goes back to the whole mTOR thing we were talking about before.

22:07So, you know, the low-protein diets seem to suppress mTOR. That also suppresses your immune system. And we know that because there is a drug that people will take, these longevity hackers, called rapamycin. That's right. Yes. That drug is actually, it's approved as an immunosuppressant. That's what it's actually for. And they give it to people who get organ transplants to tamp down their immune system. So that's a side effect that can happen if you're taking rapamycin. Maybe a side effect that could happen if you're going low protein and tamping down your mTOR. You might be also tamping it down so much that it messes their immune system.

22:44And that wouldn't show up as much in the mice studies because the mice aren't really exposed to a lot of pathogens. They're in these like clean, sterile cages and labs, right? But in the real world, we're out in society getting grubby. And we actually have some signals in other places, too, that this could be a problem. So, like, I found this very small but very interesting study. They got 12 elderly women. Half of them were on a low-protein diet, like, really low. The other half more normal. And they did stuff to them, like, they tested their immune response. They exposed them to certain antigens and then saw like how well their body kind of responded to it.

23:24Okay. Antigens like tetanus, streptococcus, diphtheria, tuberculin. They went messing around. Yeah. So what happened? So the people on the low protein diet, they didn't mount as efficient or as good of an immune response as the people on the adequate protein diet. People that are on low protein intakes have lower levels of immune markers and immune function. And that's something that Stuart and Dudley agree on. Dudley being the person that did the, you know, the big review paper we talked to earlier. Yes. He brought up a lot of these same risks and he's like, this diet is not ready for prime time.

24:03So this isn't a diet that we're advising anybody to eat right now. So does Dudley restrict his protein? No, he's saying no, he doesn't. He doesn't do it. No, not even he does. No. So this leads us to the very obvious question of when it comes to protein, what the hell should we be eating? Okay, so out in the real world, when you ask people what they eat and follow them over time, you get their food diaries, left to their own devices, people eat about between 10 to like maybe 25 % of their total calories come from protein. Without even trying or thinking, you're probably in that range. Yes. Does it make a difference if you're in the higher range versus the lower range?

24:46What do we know? So we have loads of studies looking at that. They follow people eating in this normal range. They look at the lowest protein eaters. They compare them to the highest protein eaters. They look at stuff like cardiovascular disease, cancer, death from all causes. And when we look at total protein intake, we don't see a clear signal that higher protein is worse and lower protein is better or vice versa. This is how Stuart puts it. It's effectively neutral. In other words, there's no good or bad. But then how does this make sense with that study, the small study of women that showed when they were restricting their protein, it was affecting their immune system?

25:23Because in real life, people are very rarely getting too little protein by accident. You don't have to take protein powder to meet your minimum needs. You go out on the street, pull anyone off the street in New York City, or you went outside your studio and pulled anyone off the street in Melbourne, they're almost certainly getting enough protein to meet their basic needs without even trying. The one consistent thing we do see is that the source of the protein matters. So if you're getting your protein mostly from animal sources, especially like red meat, processed meat, that's associated with some worse health outcomes.

25:57It certainly does point towards plant-based proteins as a potentially healthier source of protein. Okay, so then I think my last question is just about protein maxing. So in these studies you just talked about where people are kind of eating in this general range of, what was it, 10 to 25? Maybe 25, yeah. Percent of their diet. They're not going overboard. But now with this new trend, people are really spooning the protein in. Do you like you? I'm sprinkling. I'm sprinkling. Is this bad? Is it bad? Because that is not, this is a new trend. It wouldn't have been captured in those studies you're talking about, right?

26:46I don't know what the protein maxers are doing in terms of like the percentage of their diet coming from protein. If it's higher than 25%, they're in kind of a known person's land in terms of the science. We don't really have many studies on those. Here's what Stuart said about that. We're conducting the natural experiment in real time. Call me back in about 10 years and we'll see whether this is playing out poorly or well for most people. So we don't really know if there's going to be a downside for people going really hard on the protein. But what we do know is that they don't need to. There's this meta-analysis that looks at studies where people, they give people a ton of extra protein and have them hit the gym.