Why One Diet Never Fits All with Beth Mayer-Davis

James Hill:

Welcome to Weight Loss And, where we delve into the world of weight loss. I'm Jim Hill.

Holly Wyatt:

And I'm Holly Wyatt. We're both dedicated to helping you lose weight, keep it off, and live your best life while you're doing it.

James Hill:

Indeed, we now realize successful weight loss combines the science and art of medicine, knowing what to do and why you will do it.

Holly Wyatt:

Yes, the “And” allows us to talk about all the other stuff that makes your journey so much bigger, better, and exciting.

James Hill:

Ready for the “And” factor?

Holly Wyatt:

Let's dive in.

James Hill:

Here we go.

Holly Wyatt:

Today, we're diving into a question we hear about pretty frequently. Why doesn't the same diet work for everyone?

James Hill:

Oh, great question.

Holly Wyatt:

Yeah, one person cuts their calories, cuts their carbs, uses a plan, and loses 20 pounds. And another person does the exact same thing and maybe gains too. And that's not failure. It's just that our bodies aren't built with a one-size-fits-all playbook.

James Hill:

Well, Holly, that's where personalized nutrition comes in. This isn't just a trendy marketing scheme. It's serious. It's science driven and it's approached to understanding how your unique biology affects how you respond to food. And it's potentially changing everything from how we approach weight loss to how we prevent chronic disease.

Holly Wyatt:

If you've ever asked, why isn't this diet working for me? This episode is going to be an eye-opener because the future of nutrition isn't about finding the best diet. It's about finding your best diet.

James Hill:

Ah, great. And to help us unpack all of this, our guest today is Dr. Beth Mayer-Davis. Beth is the Cary Boshamer Distinguished Professor of Nutrition and Medicine at the University of North Carolina. Beth has spent decades studying the relationship between nutrition, metabolism, diabetes, obesity, particularly how we can use science to prevent disease and personalized care. She serves as one of the principal investigators in the NIH Nutrition for Precision Health Consortium, one of the most ambitious efforts in the world to bring personalized nutrition into clinical practice. And Holly, we also have one of those centers here at UEB. This podcast, as our listeners know, is supported through the UAB Nutrition Obesity Research Center. Beth runs the Nutrition Obesity Research Center at the University of North Carolina. Beth is someone that I've known and admired my whole career, Holly, and the perfect person to help us unpack this notion of precision nutrition. Beth, we're glad to have you with us.

Beth Mayer-Davis:

Well, thanks for having me. It's good to be here, Jim and Holly. Thank you.

Holly Wyatt:

All right, so, we're going to kick it off. Let's kind of start with a basic question to set the stage. What does personalized nutrition really mean, and how is it different from what we've been doing?

Beth Mayer-Davis:

It means exactly what it says, which is that each person can and does respond differently to the food that they eat. And so the idea is to understand what's the best diet for each person. So that's really what it means. And honestly, this is what was behind why I got in my career to begin with, wondering what was going to be the best advice I could give people that, as a young clinical dietitian I was seeing in the hospital, what was going to work for each person in front of me.

James Hill:

Beth, if I go out on the internet and I look for advice on healthy diets or weight loss, I get all kinds of stuff. And what you're saying is the same advice might work for some people and it might not work for other people. Do we know why that's the case?

Beth Mayer-Davis:

We have a good idea about the general buckets of several reasons, multiple reasons, that people might respond differently to diet. And those buckets include genetics. And genetics itself is a large bucket. Lots of different genetic drivers of how diet works in the body. So that's one. Another really has to do with the microbiome. We'll see what happens as the science progresses. This has to do with what are the little creatures, tiny creatures living in your gut primarily, but elsewhere too. Another bucket really has to do with people's both biological and cultural preferences for food. And access to food. So, lots of behavioral sort of social aspects or community aspects as well. So, really, when you think about the field of nutrition, you have to be thinking all the way from metabolism at the level of multiple types of cells in the body, that level of detail, all the way out to a person's individual behavior, their family, and their community. So that's the fun and the challenge of nutrition. And the reason people were, yeah, I know, isn't that fun?

James Hill:

It's complex, isn't it?

Beth Mayer-Davis:

Yeah, it is. But, you know, that's what makes it a challenge. It's also what makes it possible for us to understand these things over a period of time.

James Hill:

So when Holly and I do a weight loss study, for example, we see things like some people lose 20% of their weight, other people gain 5% of their weight, and everything in between. So you're telling me this could be some combination of genetics, of cultural beliefs, of behavior. How do we begin to separate all that out, Beth?

Beth Mayer-Davis:

Well, I will just reiterate that what you just described about that huge difference in response, every single weight loss diet ever done on the planet shows that. It's not just your studies, Jim, not just my studies. Every study that's looked at this, it's the same thing. So that's important for people to know. And I do want to say out loud that one of the biggest learnings for dietitians is that you don't blame the person trying the diet. Because there's so many other reasons that people have trouble losing weight. So let's stop blaming the person who's making every effort to lose weight. I just wanted to get that out there.

Holly Wyatt:

Yeah.

James Hill:

Along with that, Beth, is the diet wars. This diet is better than that diet. And it doesn't make any sense because I think what we have is enough data to show that at the end of the day, diets of different compositions produce about the average weight loss. One's not better than the other. Some people do well on low fat, some on low carb, et cetera. So we need to quit doing that.

Beth Mayer-Davis:

A hundred percent true.

Holly Wyatt:

What I love about what you said is it encompasses metabolism, genetics, the things that we talk about, but also the behaviors and puts them together. I think for so long we've studied them separately. We study metabolism or we study behaviors, but in reality, it's when you put them together that I think we're going to really move the needle. So how do you start to do that? I mean, there's so much data and so many places to interact. We can see maybe the outcome, but how do you start understanding how to predict or give somebody some, this one might be better for you? How do we even start?

Beth Mayer-Davis:

So here are four words. Math is your friend. Yeah. So, what you need is in one study, like Nutrition for Precision Health Study that Jim talked about at the beginning. We're collecting an enormous amount of data from a very large number of people that covers the whole span of all that we've been talking about. And we have our colleagues with expertise in the kind of mathematical modeling that can be in that big bucket of artificial intelligence, because it does take very sophisticated, very thoughtful math to help us really understand these drivers, because what's important for you, Holly, will be different than what's important for me and my response than what will be important for Jim. And the typical kind of math and statistics that has been used in most studies 'til very recently assumed that there was a single estimate of the effect that would be true for everybody. All right, well, we know that that actually is an incorrect assumption. So it's really, we're able now to make these studies happen because we know how to collect this enormous amount of data, and now we have the mathematical methods to be able to actually use it.

James Hill:

That's really fantastic. And to dive a little deeper into this Nutrition for Precision Health project, it's a large project funded by the National Institutes of Health. And they've invested a tremendous amount of money in this because I think we all believe that people respond differently to different diets.

And now it's time to bring the science to understand how that works. So maybe just in a nutshell, give us the top line of what we're doing in that study and maybe what people can expect down the road from the outcomes.

Beth Mayer-Davis:

Sure, yeah, we're collecting data from thousands of individuals and we're doing that in three different ways. Everyone in the study will take about two weeks during which time we'll be using continuous glucose monitoring. We'll be collecting a lot of information about what people are eating through that time period, what their physical activity looks like throughout that time period. And we'll be doing an assessment that we're calling a meal challenge test where everyone will consume the same, kind of like a smoothie, and then we will carefully measure over a few hours, over a period of time, what that individual's blood sugar looks like, and various other measures so that out of that two-week time period for those several thousand people, we'll have a lot of information that describes their metabolism, that we can link to their behavior, and that we also will be able to link to their genetics and microbiome data. So we have all that data. That's the first part of the study. In the second part of the study, individuals who did the first part can do one of two things. One, they can, as they go about their daily lives, participate in what we call a controlled feeding study. So we have three different types of diets. And for two weeks, for each of them, the study provides all of the food, everything the person's going to consume during that two-week period. So no need to cook, no need to buy food for two weeks. Yay. And so individuals consume that for the two weeks. And then at the end of the two weeks, we do a similar test to see if you have the breakfast from that diet, what happens with your blood sugar, what happens to the fats in your blood and so forth. And then in the third part of the study, if you didn't do that second, then you can do the same thing, but do it in what we call a domiciled setting. And so you would be in a research clinic for that two-week period so that everything's a little more closely controlled to collect all that data. So that's kind of the high level of what is happening, how we're collecting data for this study. And we have clinical sites around the country, and then we have lots of partnering centers to help us with the high level science for things, like all the metabolism measures, the microbiome measures, you know, et cetera, et cetera.

James Hill:

What do you think we're going to learn from this study? And let me emphasize that getting from where we are to personalized nutrition, this is one step along the way, not the end. But what do you think we're going to be able to learn from this one?

Beth Mayer-Davis:

One of the things I think is most important about this study is that we've been saying that we know already that people vary tremendously in their response to food, weight loss diets, and even if you give a bunch of people, the same slice of white bread, their blood sugar is going to change in response to that differently, one person to the next. But those studies have been relatively small, most of them. So, one of the important aspects of Nutrition for Precision Health is that we are including individuals, all adults, but from all walks of life, from all over the country, all kinds of different backgrounds. So we will be able to confirm the extent to which people vary in response to diet across numerous different kinds of people, because it's important that we make sure what we learn is relevant to the population at large here in the U.S. It's a U.S.-based study, but the fact that we'll have such a great diversity of participants, I think, is really important and important to emphasize. So that's great. The second is that, as I mentioned before, math is our friend, and we will have enough data to do what we call discovery science. So with a lot of studies, you have a really specific question. Do people lose weight on diet X compared to Y? One question, one answer. With this study, by design, we will be able to explore the data using the kind of math I mentioned.

Large language models, all sorts of statistical methods that are different that will allow us to understand what is behind that variability that we all are sure we will observe. So this is a different way of conducting science. I think that it will give us so much information straight out of the gate, and then we'll be able to design future studies to really learn, well, does that play out in the way that we expect it will play out. And so those follow-up studies will be really important because we want to see if we think that a specific diet designed based on your data, Jim, or a different diet based on your data, Holly, would be better for each of you, give you better blood sugar response or what have you, we sure better check that out. So we would need the next studies to test that out and see if it works.

James Hill:

Yeah, and it's important to emphasize that it's only recently that we can do these kinds of studies because we've never before had the capacity to analyze using complex math and artificial intelligence to really be able to bring complex factors together and make sense of them.

Beth Mayer-Davis:

That's right, because for a long, long time, especially those of us who have ever spent any time in clinical nutrition, I mean, you know that it's much more complicated than whether or not someone is following the diet that you taught them to follow, that you shared with them. So we've known that a long time and we've done our best, you know, in the real world to help people sort through that. But we have not had all of the tools to collect all of the data and then apply the math. To put it all together.

Holly Wyatt:

Yeah.

James Hill:

Holly, this is really going to be a landmark study, I think. It's going to be one of those that we're going to recognize as a turning point in how we approach nutrition and chronic disease.

Holly Wyatt:

I agree. It's cutting edge, everything kind of coming together about what we've learned and the new ways to be able to look at the data that's really going to advance the field. But I know what some of the listeners are thinking. And so when might they actually start to see some of these groundbreaking results, something that they can actually use?

Beth Mayer-Davis:

We're still collecting data, and the study is funded for another 18 months time. It was a five-year project. So it will take time to finish collecting the data in the next year or so, and then to analyze the data. But that's just the first step. Now, I will say that there certainly are companies out there that will say, send us your sample, we'll run some genetics, some other information, and we will tell you what diet works best for you. Now, some of that might be helpful. I'm not going to disparage all of that, but I will say that the products on the market now are not based on the amount of data that we're producing. And so buyer beware. You just have to be understanding, I think, of where we are relative to the science really being ready for that kind of application. So it is going to be a while, but that's just reality.

Holly Wyatt:

Yeah.

James Hill:

And that's the way science moves, right? It's step by step by step. But Holly, you know me, I'm trying to bring the optimism in here. So Beth, my next question is to ask you to predict the future. As the science moves forward, put on your future thinking hat to our listeners who, they want it now. They want to know how they can choose the best diet now. Where eventually might we get, as the science plays out, how might this help people that are looking to prevent disease and manage their weight?

Beth Mayer-Davis:

So I also am a perennial optimist. So we share that. We've always shared that, Jim.

James Hill:

Holly's the opposite. She's glass half full.

Beth Mayer-Davis:

Oh, well, good. It's a good trio here. I would say two things. Individuals often already know a fair amount about what works for them. So I think it's to clinicians to listen to their patients and work with that, incorporate that. Because people often do have a pretty good sense like, dang, I tried that keto diet. I thought it was going to work wonders but for me, a lower fat diet happens to work better, which is almost counter to what most people would think today, right? So, listen to what individuals are telling you, because I think people should feel empowered that the reason one diet didn't work well for them and another did, it's not just in your mind. There easily could be real genetic, real metabolic, real reasons that that's actually true. So I think I would love for people to feel empowered to observe themselves and recognize and validate that they're responding differently to diet. Well, you know what?

Let's pay attention to that. So that's one thing. The other is that I'm imagining that there'll be some statistical analyses that are kind of in between the, I'll call it the old-fashioned approach, compared to development of an algorithm that gives you an individualized dietary recommendation. And that place in between could be for subgroups of people. For example, older adults, their metabolic rate's a little bit slower. That might be a group where we can identify certain diets or patterns that seem to be a bit better. Or, for example, people who have diabetes. I'm a diabetes researcher. There are lots of reasons where various diets might work better or worse for individuals with type 1 diabetes or type 2 diabetes. So these subgroup analyses, I think, can also be really helpful as we move forward towards understanding the best diets for people. So those would be my two thoughts, I would say. So we don't have to wait till perfection. We're going to get there scientifically, but we don't have to wait before we start thinking differently about diet for people.

Holly Wyatt:

Yeah. So that kind of leads me to where I hope we were going to. We're going to go a little bit in this podcast is what can people do today? Is there any tools out there? We're not to where we're going to be, but are there any tools like CGM or anything that we can start looking at to start personalizing? And I love what you said.

You know your body. You have your own data and to use that. But are there some things that people who aren't in the study, we don't have to wait for the study, might could start using to personalize their plan?

Beth Mayer-Davis:

Yeah, I think one might be for people to take a moment and just kind of recall what's been true for them in the past as just kind of their baseline understanding of themselves. Can do that. The other is that there are lots of readily available apps and tools to monitor your diet and your physical activity. I'll just name one MyFitnessPal, which I'm not advocating that versus another one. There's lots of apps available to be able to just start to monitor your own diet. And we know that self-monitoring what you eat is very helpful for weight management no matter what because it just raises your awareness. So even short of going to fancy monitoring devices, just starting with monitoring what you're eating, and monitoring your weight along with that over a period of time, maybe it's a month, six weeks, two months, more than one or two days, just to sort of start to get an idea about what's going on with you. And I don't know that everybody would agree with this, but I personally would start with that before jumping to something like continuous glucose monitoring. That's my opinion. And we can talk about continuous glucose monitoring. I'm a fan. I use that in all my studies, but then again, I'm a diabetes researcher. But I think let's start with what people do, which is you eat every day and people can often watch their weight. So maybe just starting there would be helpful to many people.

James Hill:

I kind of agree with you, Beth. I think continuous glucose monitoring is wonderful if you have diabetes. It's very, very useful. I think the question is still open to the usefulness of people that are trying to use that to manage their lifestyle. And again, I don't think we have enough data yet to know the usefulness of that. I hope we gather more. And I think in the future, you and I might change our opinion if we see some science suggesting that it's helpful.

Beth Mayer-Davis:

I agree. That was really well said.

Holly Wyatt:

I guess I disagree a little, which is not unusual in these podcasts. I agree in the fact that we don't have the data yet. But I think if people use them to gather some data about themselves and how they feel and the numbers. And for certain individuals, I'm not sure. I think that can be helpful. I don't know that we have science to say if it does this, this is what it means. But if you're being your own person and you're looking at your own data, it's like, oh, what's going on with me? I hesitate to just tell people, just do the wait and see what happens. They want more than that. So, what can we offer them that's a little bit more than just do the diet and see if it works. And they're like, I've been doing that my whole life, Holly.

Beth Mayer-Davis:

Well, remember what I said is not us saying do the diet. What I was saying is for a person to eat what they eat and really monitor that carefully and weigh themselves and see what happens over time, just starting with what the person themselves normally eats. The concern I have with CGM for people who do not have diabetes, and I will tell you this is life-changing for people with diabetes, especially people with type 1, life-changing way more than even the introduction of the insulin pump. I could go on about diabetes, but I won't unless you ask me. But otherwise, for people whose blood sugar is within a normal range, what is it really telling you? Because it's just one measure. It's your glucose. It's your blood sugar. It's not so many other measures that are part and parcel of what contributes to weight gain or weight loss or cardiovascular risk, for example, or risk for cancer or risk for various orthopedic problems that come along with excess weight and weight gain. I worry that people without diabetes focusing on just that one measure of blood sugar, I don't know why that's particularly helpful to them. I think it's one of these things where just because you can does not mean that you should. Just because we can monitor glucose over time doesn't mean that it's helpful, for people who do not have diabetes.

James Hill:

All right. On that one, stay tuned.

Beth Mayer-Davis:

On that one, stay tuned. You know, my mind could be changed with data.

James Hill:

Oh, well, that's one of the things about science. I mean, my mind has been changed many times. So I think one thing, and the data proves me wrong. One of the issues, I want to change direction here a little bit, because one of the problems in the nutrition world is that we don't have very good ways of measuring what people are actually eating in the real world. So look at the physical activity side. I can put a monitor or something on, and I don't have to do a single thing. It's being measured for me. I think one of our limitations on the nutrition side is we don't have a good way of doing that. We rely on self-reports and other kinds of things, which we know aren't really accurate.

Beth Mayer-Davis:

What a great question. And it causes me to remember that I forgot to say something really important about nutrition for precision health. So I'm so glad you brought this up, Jim. And that is built into the study is an assessment of a couple of different methods, new methods to assess dietary intake. So perhaps many of our listeners are familiar with a 24-hour dietary recall, which either could be done online or an interviewer can basically ask you everything that you ate in the last 24 hours. And there's a very specific method for how that's done. And there's been lots of studies about the relative accuracy and inaccuracy of those approaches. But it's what we've been stuck with. So more recently, there's been different methods, one of which has to do with use of cell phone photography to help document what people eat. So taking a picture of your plate of food or your snack, and then taking a picture after you've finished that meal or snack to see what's left. And with some pretty cool computer magic, there can be quite an accurate estimate of what that food contained in terms of nutrients, vitamins, minerals, protein, fat, et cetera, et cetera. And that can be really, really helpful to use that new technology. A mobile food record is a way that we sometimes refer to this. And there's another technology that is super cool. You can imagine Google Glass and I'm wearing glasses at the moment. Listeners, you can't see that that's the case, but I'm wearing glasses at the moment and imagine a little tiny camera stuck to the temple of your glasses that will watch what you're eating. Now, that sounds kind of weird, but that is another way to objectively confirm what someone is eating. And I want to, again, make sure that we're not sort of blaming the very people that we're talking about and wanting to help, including ourselves. It's hard to remember what you ate yesterday. Everybody lives busy lives. Nobody's doing anything wrong. It's just really hard to remember what in the world you ate at two o'clock yesterday afternoon. I don't know. So these are ways with cell phone photography or this sort of Google Glass light camera device that can help with objectively assessing what people are eating. So that will be helpful.

James Hill:

Cool. I have another question. It relates a little bit to what we're talking about before. Some of our listeners are helping work with people, helping them change their diet, maybe registered dietitians or clinicians. What's your message for them regarding the issue of personalized nutrition?

Beth Mayer-Davis:

It's really the same as what I would say for people trying to improve their health through nutrition, which is to be observant and collect the information to really see how your patient is responding to a particular diet. Don't start with the assumption that if there's not obvious success that the person wasn't trying hard enough or didn't adhere to the diet. It might be that they need additional information. It might be that they need guidance in terms of selection of food at a grocery store or dealing with how to handle family dinner when you're trying to eat differently than the rest of your family, et cetera, et cetera. That might be the case that they do need help. It might also be the case that their genetics and their metabolic, their biological processes, including but not limited to microbiome, are such that the diet is just not going to work for them. So I think awareness is first, making sure the person is supported with whatever diet they're trying, but then to pivot if the diet's not working for them, including if it's just too darn hard to follow. Then pivot to try something different. Don't keep blaming people. Don't keep going after a diet that actually may not work for them. It's just like medication. That's the analogy.

There's for trying to fix any particular thing. There's often several classes of drugs. You try one, it might not work. You try the next. Very similar way of thinking in this case.

Holly Wyatt:

Yeah. So I'm going to ask a question. I'm surprised Jim has not asked this question. This is always the question.

James Hill:

I was going to get to it.

Holly Wyatt:

Oh, no. I'm going to beat you to it. So the way you've kind of been talking about it, it's thinking a little bit that nutrition is the major player. How do you now start putting in, let's just put in one thing, physical activity. So you have someone, they're eating one diet and then their physical activity changes and you see changes. How do you know it's because of the diet? How do you know it's because of physical activity? How do you start putting all the factors that we know interact into making these decisions about nutrition?

Beth Mayer-Davis:

Love it. That's such a great question, Holly. For the NPH study, this is actually why we're measuring so many different things because we'll be able to do some of the maps to help us put those pieces and parts together. We already do know there's already a literature that for some exposures to diet, people who are physically active respond differently. Almost always in the case that physical activity is going to be good for you and may actually mitigate some of the negative effects of some types of diet. So we already know that physical activity can change the way a person responds to diet, especially if we're thinking about weight and all of the many, many health conditions that are impacted by weight. Physical activity is absolutely critical. So great question, Holly. And lots of ways to think about that, but it is often the case that you would not want to just address diet. You would want to consider diet and physical activity.

James Hill:

Beth, we talk a lot about that and a lot of people that focus on physical activity focus just on burning calories, but it's way more than that. I mean, if you look at what physical activity does, it affects your insulin sensitivity, it affects mitochondria in your muscle, it affects your microbiome. So one of the ways that we approach it, if you're a fit person, you have a different metabolism than an unfit person. And obviously, you're going to respond differently to diet. And I'd like to look at elite athletes. They're just consuming, I mean, my gosh, they're consuming sugar and calories and everything else. And I'm not saying it's all physical activity. Physical activity gives you that ability, I think, to be more flexible with your diet.

Beth Mayer-Davis:

I think that's true based on the data that we have so far and everything that you described 100% and even like a very active muscle is going to look at different sources of energy for active muscle than some other tissue. So there's lots of reasons that drill into the very specific metabolic pathways that are important that turn out to be visible on your scale, right? So, you know, that's right.

James Hill:

Yeah. One of the things I've always felt is just crazy is that we developed a nutrition research field differently from an exercise physiology field. And to me, they're the two sides of a coin. And you can't look at one without the other. If you tell me what you're eating, I need to know your physical activity. If you know your physical activity, you need to know your diet. So I wish those fields could come together a little closer. And maybe in precision nutrition, we can bring those more together.

Beth Mayer-Davis:

I think that's great. I'll tell you, in my own program of research and in the doctoral students that I've mentored, I've had students who already were trained at the graduate level in exercise physiology and came to get their PhD in nutrition. What's fabulously interesting dissertations and research and what insights people bring with one expertise adding to the other. And the reverse side, too, where we train people in nutrition who go and do postdoctoral training in exercise physiology. Because putting those pieces together should not be unusual. We shouldn't have to work that hard to bring it all together.

James Hill:

Right. Right.

Beth Mayer-Davis:

You're quite right. I think that in so many ways. I'm not sure how or why those fields develop over time so separately and they come together in lots of different ways. But it's unfortunate that they got separated way back in the early days to begin with.

James Hill:

I noticed, Beth, that a lot of times registered dietitians will go out and get training and exercise because as they get into it, they realize that's missing. And I think we've got to do more to sort of bring those together.

Holly Wyatt:

And I think the thing that's missing still is bringing in the mind, the mind part of this. So it just shows how complex it is. Yes, you got how many calories are coming in. You got how many calories are burning. That's oversimplification. But you got intake and expenditure and nutrition and energy and activity, but also what you're thinking and how you're using your mind state, I think, plays a huge role more than we recognize in outcomes, actually in the outcomes. But I think we're behind on that. So I think that's coming.

Beth Mayer-Davis:

A little bit. I think part of the question is what's been happening in research and what's happening in clinical practice. Because, and you guys know this, from years ago, take the Diabetes Prevention Program. Talk about a landmark study. My goodness. That project, for our listeners, was an approach to weight management and physical activity for people who were at very high risk of developing type 2 diabetes. And it was wildly successful. And that study incorporated not just delivering of information about diet and about physical activity, but paid a great deal of attention to psychosocial support for behavior change. And that study has turned out to be the core of diabetes prevention efforts all across the country now for many, many years. And that's just one example. So I think on the science side, there's been reasonable progress. Maybe is an okay way to say it, reasonable progress. And putting together the pieces of diet, physical activity, psychosocial, behavioral aspects required for the outcome that we want. But the question is, is that happening in clinical practice? And I think probably some places it is, and in a lot of places it's not, because unfortunately, our areas of expertise are so siloed. And I could go on about reimbursement for the counseling required to do that well.

James Hill:

Yeah.

Beth Mayer-Davis:

I could go on, but I won't.

Holly Wyatt:

I think there's a lot of check the box. We're doing it and you're not really doing it when it comes to that area. And it's a little bit fuzzy exactly what it is, that piece. But I think that's the missing piece for so much of this. And you can put someone on a diet and a physical activity plan and it will be very different without that third part.

Beth Mayer-Davis:

I mean, I know in training of RDs, which we do here at UNC Chapel Hill, we have a master's program that's coordinated. People are prepared to sit for the registered dietitian exam. And they're trained and they have been for years in all of this. And we're not unique. I love our school and it's a great program, but that's true in many, many other programs around the country. I think, though, that one of the barriers is that there is very limited reimbursement for the amount of time that it takes for a registered dietitian or other clinician to provide that kind of counseling and information and support that's needed for people who are out in the real world living in what we've all come to call an obesogenic environment where everything's working against you, to have giant portion sizes and to sit. I think that the reason we don't have all those pieces put together and highlight, I completely agree that we don't have all those pieces put together. But I'm not sure that it's so much because we don't know. I think it's that we don't have the systems that allow us to do what we know at least reasonably well how to do in many cases.

James Hill:

Okay, Holly, you know what it's time for?

Holly Wyatt:

Listener questions?

James Hill:

Listener questions.

Holly Wyatt:

Yes, my favorite.

James Hill:

Want me to go first?

Holly Wyatt:

Of course.

James Hill:

So, Beth, here's a listener question. To get started with personalized nutrition, should I do a DNA test or a microbiome test? Would that help?

Beth Mayer-Davis:

I think that that would not help because we don't have enough of the science yet to understand how that might help you. There might be a finding or two, but it would be isolated and not a good way to really think about what's your overall diet that will lead to your best health. So I don't think that's really a good place to start at this point in time.

Holly Wyatt:

Yeah, we just don't have that data yet. It may be in the future, but I just don't think we know what to do with it. And you talked about this earlier, people will tell you, you can sign up and they're gonna try to tell you, but the data is really not quite caught up with what they're telling you yet. So here's the second question. Is what we're talking about, this precision nutrition, is it really gonna only be for people with diabetes or a chronic condition, or can anybody benefit?

Beth Mayer-Davis:

I think everyone will be able to benefit. I do think especially people who have what we sometimes call nutrition-sensitive conditions, so people with diabetes, cardiovascular disease, various other chronic conditions, are dealing with something for which nutrition is especially important. But I do think that as we go along in this field, this will benefit everyone.

James Hill:

Here's the last one. I've been trying to lose weight, but I've hit a plateau. Can personalized nutrition help me?

Beth Mayer-Davis:

Yes. And here's a little tidbit for the day. Remember that if you've lost weight, first of all, congratulations. And you now have less weight that you need to move around. So it's going to take fewer calories to move around that weight. So sort of automatically to lose more weight, you're going to have to drop your calorie intake even more. Not because anybody did anything wrong but because there's just less of you to move around. So it takes a little bit less calories. So that's just like a little off the wall tip for the day. And I also think that this issue of a weight hitting a plateau and what does it take to get off that plateau, continue to lose weight. That will vary according to who you are so personalized nutrition I do think will be able to help with that as well.

Holly Wyatt:

All right, let's do some vulnerability questions.

James Hill:

Ooh, love these.

Holly Wyatt:

All right, I'm gonna go first. I'm gonna go first on this one.

James Hill:

You go first.

Holly Wyatt:

Because I have this, I like this one. Have you ever made a change to your own diet or habits based on new research findings? And what was that change?

Beth Mayer-Davis:

Yeah, my diet has evolved over the years. I've been in this field because man, if I don't believe the data, who the heck will, right? So I would say my diet now is way more leaning into a Mediterranean-style diet. Olive oil is my friend. I've definitely been eating more beans and legumes of late. I definitely eat more fish than I did 10 years ago, what have you. So I won't say that, in fact, I don't think I've ever made a drastic change in my diet from Tuesday to Wednesday because I read a new paper on Tuesday. It's more a gradual change over the course of literature that accumulates over time. Because just like Jim said earlier, science does move more slowly than we would like. And a lot of that is because we need to see if a second study confirms a first, you know, and really understand these things from a perspective. So yeah, personally, I have changed my diet as a matter of the science of nutrition over time.

James Hill:

Cool. All right, I'll ask one, and this is one we ask a lot of people and it's surprisingly hard for people. But Beth, you've been at this for a while. What's something you got wrong? That you were wrong about and you had to change your mind based on the science and moving forward?

Beth Mayer-Davis:

Oh, man. Okay, let's see. When I was first thinking about nutrition and diabetes, I and all of us were really thinking about low-fat diets. Well, if you have a low-fat diet, you're likely to have a higher-carbohydrate diet for the same number of calories. Flip that. It turns out that there is now accumulating evidence that it's easier to manage, particularly type 1 diabetes, with a lower carbohydrate intake for lots of reasons, which implies a higher fat intake. But again, I just mentioned earlier, olive oil is my friend. So it's not about total fat. It's about the fats that you choose and those that are much more likely to promote cardiovascular health, and in the case of someone with diabetes, to allow them to more easily control their blood sugar. So, yeah, based on the science, started out one place, that was wrong. It was the science we thought we knew at the time. Fast forward, science changed, we were wrong. Hopefully now we're closer to right for at least most people with diabetes.

James Hill:

And that's how science moves forward. You have a hypothesis, you test it. Sometimes you're right, sometimes you're wrong. And sometimes it's the wrong ones that help us rethink how to ask better questions.

Beth Mayer-Davis:

That's right. Every scientist has to be willing to say, yep, I was wrong. The hypothesis has proven me wrong. Move forward, learn. That's why we're in science.

Holly Wyatt:

And I think also it is good to be able to realize there's probably some things we think are correct right now that aren't. They're going to evolve. It's going to change. It's going to move slowly, like you said, and we're going to have a little bit different way of thinking about them. So I'm always like, there's nothing that is potentially, we know this and it's written in stone. And I think you have to be open to that to really be able to move the field forward.

Beth Mayer-Davis:

And it is frustrating to the public, I will say, because you have to make public health recommendations and clinical practice recommendations based on the science that you know. Because people are out there today. But that might change as a matter of the science moving forward. So it's not that the organizations that put forward recommendations did something nefarious or intentionally bad. It's that the science changes and we are obligated to change our recommendations accordingly when the science changes.

James Hill:

Love it. All right, Holly, let me see if I can summarize here.

Holly Wyatt:

Okay.

James Hill:

This issue of precision nutrition is really important. I think we have lots of real-life data suggesting that not everybody responds the same to the same diet. Now what we're trying to do is to bring the science to bear to understand why that is. And maybe where we're going in early 2029, you'll be able to go on your app, put in your information, and it will tell you the best diet for you. We're not there yet, but we're moving forward to do that. In the meantime, I think people are doing trial and error on themselves with the understanding that if you fail on a certain diet, it may not be due to your willpower or anything. It might be that that's not the right diet for you. And people helping change diets or manage weight should understand that. It's not necessarily a failure of the person, and we're still a little bit in the trial and error field, but I think the science in this area is tremendously important. And I really hope NIH continues to fund the science that's ultimately going to lead us to that app to tell you the best diet to maximize your health. Beth, you agree?

Beth Mayer-Davis:

I completely agree. And I'll just extend that to include individuals of all ages. Apps that would help us make sure we're providing the best nutrition for our children and for adults and for our parents and our grandparents all across the lifespan.

James Hill:

Perfect. Well, Beth, thank you. You've been great. And again, thank you for all your work. I've known you for many, many years. And what you've done at UNC with the nutrition program and all your research has really, really made a difference. So thank you for all you do. And thanks for giving us your time today.

Beth Mayer-Davis:

And thank you, Jim and Holly. It's just such an honor to work with both of you. So I really appreciate being here. Thank you.

Holly Wyatt:

Thank you.

James Hill:

All right. Let us hear from you. We love your questions, topics that you want to address, and we'll see you next time on Weight Loss And.

Holly Wyatt:

Bye, everybody.

James Hill:

Bye. And that's a wrap for today's episode of Weight Loss And. We hope you enjoy diving into the world of weight loss with us.

Holly Wyatt:

If you want to stay connected and continue exploring the “Ands” of weight loss, be sure to follow our podcast on your favorite platform.

James Hill:

We'd also love to hear from you. Share your thoughts, questions, or topic suggestions by reaching out at [weightlossand.com](http://weightlossand.com/). Your feedback helps us tailor future episodes to your needs.

Holly Wyatt:

And remember, the journey doesn't end here. Keep applying the knowledge and strategies you've learned and embrace the power of the “And” in your own weight loss journey.