Why is everyone so obsessed with protein?

A food historian and nutrition researcher dig into the protein-maxxing trend—and explain why you might want to up your fiber intake instead.

Speaker names marked ? are inferred from speaking time and the show’s known hosts — they are not voice-verified.

• 0:00Speaker 00

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• 0:14Flora Lichtman?

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• 1:00Ira Flatow?

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• 1:19Flora Lichtman?

  Hey, it's Flora, and you're listening to Science Friday.

• 1:24Flora Lichtman?

  Stroll through any grocery aisle, and it's pretty much impossible to ignore the latest nutrition trend. Protein maxing. There's protein chips, protein-packed ice cream, sparkling protein water, not to mention the FDA's updated food pyramid, which puts steak and a roast chicken at the very top. So where did this protein craze come from? And how do we know how much protein we actually need? Here to take us into the history and the science are my guests, Dr. Hannah Cutting-Jones, a food historian at the University of Oregon, and Dr. Christopher Gardner, nutrition researcher at Stanford University School of Medicine. Hannah, Christopher, welcome to Science Friday.

• 2:06Speaker 03

  Happy to be here.

• 2:07Speaker 04

  Thank you so much.

• 2:08Flora Lichtman?

  Thank you both. Christopher, let's start with the science. Where did the recommendation for 50 to 70 grams of protein a day come from?

• 2:18Speaker 03

  Yeah, it's really old. It goes back maybe 70 years. One of my professors at Berkeley did this. There's something called a nitrogen balance study. They incarcerated people. They put them in suits. They lowered their protein to zero. They raised their protein back up. Nitrogen is unique to the amino acids in protein. And if you count all the nitrogen leaving the body, poop, pee, slough cells, and everything entering the body, food, you can do this study and say, oh, here's how much I need to eat to replace what I lost.

• 2:49Flora Lichtman?

  And so what was the final recommendation from those studies?

• 2:53Speaker 03

  So it was that the average person needs 0.66 grams per kilogram body weight per day, which is ridiculous because Americans don't use kilograms. So it's 0.3 grams per pound of body weight. But they added a safety buffer because they realized not everybody's average. And so the real recommendation is 0.36 grams per pound of body weight per day. Bigger people need more, smaller people need less.

• 3:20Flora Lichtman?

  And do we feel like that science holds up? Like, is that actually a good way to measure how much protein we need by looking at how the skin cells that come off in our poop?

• 3:31Speaker 03

  Well, it sounds like that wouldn't be optimal. That would be minimal. But in fact, what's really ironic, and the reason most people don't really pursue it, is we have this great nutrition database that we collect for Americans, and we have been for decades. And Americans eat 50% more than the RDA. The RDA is the Recommended Dietary Allowance. It's 50% more than the thing that has the safety buffer. So we eat a safety buffer on top of the safety buffer before we even have the protein Pop-Tarts.

• 4:01Flora Lichtman?

  Wait, so you're telling me that I get enough protein likely?

• 4:05Speaker 03

  So protein has never been on the list of nutrients of concern in the health community. Many other nutrients, especially fiber, are of more concern than protein, unless you're not getting enough food to eat. With a reasonable variety of food, you're getting enough protein. Stop obsessing about protein.

• 4:26Flora Lichtman?

  Hannah, where did this craze come from then? Like, why do I feel like I don't get enough protein if I likely get, almost certainly get enough protein?

• 4:36Speaker 04

  The obsession with protein or the interest in protein goes back a very long time. We have to go all the way back to the 1840s when there were chemists, particularly in Germany, who were studying the different components of food. And they isolate the macronutrients, right? Protein, carbs, and fats. But they really landed on protein as being the most important of the three. And what's key to understand is that protein at that time was particularly linked to meat consumption. And so for a long time, there's been this reductionist way of seeing nutrition, really, which is part of the problem that we're talking about today,

• 5:18Speaker 04

  which is that people equate eating muscle with gaining muscle or eating fat with getting fat. But protein was really kind of under the radar for a long time. During the 1900s, for example, the main people who were interested in protein were scientists studying how much protein, for example, working-class people needed as part of the Industrial Revolution and urbanization. And they were recommending a lot of protein for people who were doing manual labor, that kind of thing. But also, bodybuilders and weightlifters became really interested in protein consumption in the 1950s.

• 5:57Flora Lichtman?

  Wait, Jim Bros in the 1950s were pushing protein?

• 6:00Speaker 04

  Yes, yes. Bob Hoffman was one of the first to develop a high-protein, kind of a sludge, chocolate, disgusting blend that he made in his gym. He was the weightlifting coach for the US weightlifting team in the 1950s and 1960s.

• 6:18Flora Lichtman?

  That's the original chicken shake.

• 6:22Speaker 04

  It was made with soy protein powder, actually. But yeah, they were really interested in the first kinds of supplements of protein. And this has been happening a long time, that people have been trying to supplement their diets with protein. Throughout the 1900s, people are getting into bodybuilding, but protein is still a very niche product at that time. In the 1970s, we have the first nutritional congressional committees that are starting to put together what we should be eating as Americans. And the first food pyramid comes out in 1992. And we have the meat industry really getting involved in shaping those recommendations.

• 7:05Speaker 04

  So what people heard from all of the studies that happened in the 1950s to the 1980s, which were linking high consumption of saturated fat, mainly red meat, to coronary heart disease. It's called the diet-heart hypothesis. The meat industry stepped in with these recommendations and said, you're not going to say that people aren't going to eat meat. Like, absolutely not. And so they changed the recommendations. They go back and forth. And in 1992, when the food pyramid comes out, really dumbs down and makes the language very vague for Americans. And so what they hear is eat less fat. And that's when we start the whole vilification of fat in the 1990s that I certainly remember well,

• 7:48Speaker 04

  with Snack Wells and Wow Potatoes, and low-fat, no-fat, everything. So if we fast forward, in 2003, some very important studies come out linking high-protein diets with weight maintenance and weight loss. And this really opens the door to protein products being marketed toward a whole new demographic, people who are trying to lose weight. And it kind of changes the protein game.

• 8:22Flora Lichtman?

  Christopher, you must have had a front-seat view to all of this because you were working in the field at the time.

• 8:27Speaker 03

  Absolutely. We did two major weight loss studies, one with four diets that ranged in fat and carbs, and one with just two diets that were low carb and low fat, pitting them against each other. And the real irony here is there wasn't much focus on protein in those. And I can tell you that low-fat, low-carb were a total tie for the most part. Really didn't matter. Our final conclusion was that if it was a good-quality low-fat or a good-quality low-carb diet, you should focus on the quality of the foods more than the low-fat or the low-carb. But what's really ironic is how stable the protein was. Here's my favorite study. One other than ours had 800 people in it, and it was two years long.

• 9:10Speaker 03

  And there was a low carb and a low fat and a low protein, and there was low and high of everything. The two protein levels were intended to be 15% of calories and 25% of calories. That was pitting low versus high. Because normal protein intake, almost all around the world, is 20%. It's really sort of amazing how consistent it is. It's called the Pounds Loss Study. I can't think of anything that makes this point clearer. At the end of the study, the two of the four groups that were randomly assigned to different things that were supposed to get 15% protein had migrated back to 20. And the two groups that were supposed to have 25% protein had migrated back down to 21. And so, to be honest,

• 9:55Speaker 03

  they couldn't actually test the hypothesis of whether a high or a low protein diet is different because real human beings couldn't do it.

• 10:05Flora Lichtman?

  That's so fascinating. I mean, I want to ask you a little bit more about this. You know, the protein maxers, to go back to Jim Bros for a second, like, are looking to exceed the daily recommendations of protein. Can you store it? Like, could I build up my protein reserves to use for a rainy day?

• 10:23Speaker 03

  And this is the best question to ask. Thank you, Flora. But just to put it in perspective, we can store an infinite amount of fat in our bodies, every place you look. We can store a limited amount of carbohydrate. For the people who are runners and they try to carb load, they try to build up their carbohydrate stores in their liver and their skeletal muscle. But for protein, there isn't a single place you can store it. If you have protein maxed, at the end of the day, when you've maintained your cell repair and your enzymes and hormones and hair and fingernails, everything that's left at the end of the day gets converted to carbs. You break the nitrogen off, you turn it into carbs. And if you've got your carb storage all set, you turn that into fat.

• 11:08Speaker 03

  By eating that much protein, you're pushing other foods off the plate. You're not getting enough fiber. You're not getting enough vegetables and legumes and beans. And you're not getting a well-rounded diet, especially if it was a supplement on top.

• 11:23Flora Lichtman?

  When I see, you know, a protein-packed cracker or protein water, where is that protein coming from?

• 11:31Speaker 03

  It's mostly whey and soy.

• 11:33Flora Lichtman?

  Yes.

• 11:34Speaker 03

  Like, half of it is whey and half of it is soy.

• 11:36Speaker 04

  Exactly, exactly. And yeah, whey protein used to be just a product that was thrown out after the cheesemaking process. It was considered a total waste. And then it started to be, people were like, oh, we can put this into these shakes as a form of added protein. And it became a multi-billion dollar business, you know, fairly quickly.

• 12:00Flora Lichtman?

  I've got to take a break. But when we come back, I want to talk about another dietary trend: fiber maxing.

• 12:08Speaker 03

  Ready?

• 12:09Flora Lichtman?

  Stay with us.

• 12:15Speaker 00

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• 14:18Flora Lichtman?

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• 15:03Flora Lichtman?

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• 15:17Flora Lichtman?

  Hannah, fiber maxing also seems sort of relatively new and trendy. Is it?

• 15:22Speaker 04

  I don't think so. I mean, I think the original fiber maxer would have to be John Harvey Kellogg in the 1870s.

• 15:32Flora Lichtman?

  The breakfast cereal Kellogg, yeah?

• 15:34Speaker 04

  Yes, yes. He and his brother Will, they developed the first bran flakes, corn flakes. They were on a mission to replace greasy, meaty, heavy diets with more plant foods, fiber-rich foods. There's been an element of people pushing fiber and fiber-rich foods for a long time. But I think it's kind of a more recent trend. I mean, it's interesting to think of the last 10 or 15 years, right? Where proteins become very politicized in a way that it really wasn't before. And there's been the kind of this cultural trend to connect protein and particularly red meat consumption with being American, you know, part of this whole manosphere thing.

• 16:19Flora Lichtman?

  Yeah, skill in, yeah.

• 16:20Speaker 04

  And fiber is kind of, I think, the flip side of that. We don't get enough fiber in our diets. And only 5% of Americans eat enough fiber. And it's a real problem. But fiber is also not a really sexy nutrient, the way that protein is. Protein is connected with appearance, performance, being at the gym, working out, hanging on to muscle as you age, losing weight, all these things. And fiber, we kind of connect to our grandparents and prunes or something. But it's actually...

• 16:54Flora Lichtman?

  And pooping. I mean, fiber, we connect to pooping, right? Why do we need fiber, Christopher?

• 17:00Speaker 03

  Okay, so why do we need fiber? Let's talk about the definition of fiber. It's really a carbohydrate-like molecule. And for all the carbs that we absorb and use for energy, we have enzymes to break down a bunch of them. But we have none to break down the different fibers. So kind of the definition and nutrition of fiber all along has been a carbohydrate-like molecule. You can't break down and absorb. So every bit of it goes to your colon.

• 17:25Speaker 03

  And then part of that was, oh, it keeps you regular. Oh, it helps prevent diverticulitis. Oh, it helps your GI health. But the newest kid on the block is actually the most fun, and that is the microbiome. So I think that actually is a component of the fascination with fiber. Because it turns out that there's way more bacteria in our guts than anybody ever thought. These are actually bacteria that have a role in health. So there's good and there's bad bacteria. The balance is very important. They thrive on eating the fiber that makes it to the colon. They have, the bacteria have the enzymes that chew it up. And what happens is, they generate metabolic byproducts

• 18:10Speaker 03

  when they're fueling themselves, that we absorb in the colon, and it lowers inflammation. And this was underappreciated before. And we actually have a lining in our gut, a mucus lining, that's made of very much the same carbohydrate-like molecules. And in the absence of fiber, the bacteria will chew the lining and thin it. And it's probably leading to leaky gut syndrome and inflammation by thinning that protective lining. So the microbiome has made fiber a new hot, cruel kid on the block. And people are sending in their poop and paying money to have their microbiome analyzed. And to be honest, the commercial industry is once again ahead of the science.

• 18:53Speaker 03

  The simplest thing is, you know what? It's probably important, you should eat vegetables and fruit and legumes.

• 19:01Flora Lichtman?

  Whole food max.

• 19:02Speaker 03

  And not since, yes, we should whole food max. That would be a better way to do it all. Thank you, Flora.

• 19:07Flora Lichtman?

  Christopher, are there different varieties of fiber and protein?

• 19:12Speaker 03

  Okay, so protein is made of 20 amino acids. And all foods, including all plant foods, have all 20 amino acids in different proportions. And they're actually stunningly similar. The distribution of amino acids in chickpeas and lentils and whole grains is really more similar to meat than most people think. There's less of the protein. Meat has a lot more protein. But the proportions are important, like a Scrabble game. In Scrabble, you have different numbers of letters in that bag of Scrabbles. Because when we spell words, we use As and Rs and Es way more than we use Zs and Xs. And amino acids are kind of the same thing. And so you can easily meet your protein needs with plants.

• 19:57Speaker 03

  When it comes to fiber, Flora, yes, there are whole classes and categories of fibers, dozens and dozens of classes. And they all have different molecular structures. And we don't have the enzymes to break any of them apart. They're pretty fascinating for the microbiome. And it would be great if personalized medicine in the near future would say, oh, my God, Hannah, we have analyzed your microbiome. And you're pretty sure on Akkermansia. And so we're going to find a way to give you that microbe that you're missing. And once you've got it, we think you could feed it best with chickpeas or lentils or oats. But we actually don't know that yet. So the field is sort of moving to that place, where here's the microbe you're missing,

• 20:41Speaker 03

  and here's the best source of it in a grain or a nut or a seed or whatever. And so, oh, my gosh, this is going to be horribly complicated, everybody listening. But until we know more, eat more legumes and vegetables and fruits.

• 20:57Flora Lichtman?

  Here's my take home: eat legumes.

• 20:59Speaker 03

  Thank you. Be part of the leguminati and be really intelligent about your food choices.

• 21:05Flora Lichtman?

  Leguminati. That is the best thing I've heard in so long. I want to thank you both for being with me today.

• 21:13Speaker 03

  Thank you, Flora.

• 21:14Speaker 04

  Thank you, Flora. This has been fun.

• 21:16Flora Lichtman?

  Dr. Hannah Cutting-Jones, food historian and assistant professor at the University of Oregon, and Dr. Christopher Gardner, nutrition researcher and professor at Stanford Medicine's Prevention Center and author of the new book, Food Sense: What to Eat and Why.

• 21:40Flora Lichtman?

  And one more thing before we go. We are calling all foragers. If you're that person who collects roots and fruits and fungi, we want to hear your best and your worst foraging stories. Maybe you had a close call, maybe it was an epic call. Whatever it is, we want to hear your story and why you do it, why you forage. 8774 Sci-Fry is our number. That's 8774 Sci-Fry. And please include all the delicious details. This episode was produced by Shoshana Buxbaum. I'm Flora Lichtman. We'll catch you next time.