**Jim 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.

**Jim 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.

**Jim Hill:** Ready for the “And” factor?

**Holly Wyatt:** Let's dive in.

**Jim Hill:** Here we go. Holly, one of the really hot areas in obesity research and nutrition research is the role of the microbiome. That's the bacteria in your gut and influencing your body weight, your health.

I mean, it influences everything. Today, we're going to explain how your gut and the bacteria in your gut could impact your body weight and your health. We're going to talk about are there things you could do to make your microbiome optimum?

**Holly Wyatt:** Yes, microbiome. Jim, that's a really fancy word. We're going to have to define that a little bit better, but I get lots of questions all the time about what people should be eating, talking about yogurt and fiber and probiotics and prebiotics. Even I get a little confused. I'm looking forward to getting some expertise in this area. I personally want to know, do I have a good microbiome or do I have a bad one? That is what I hope to find out.

**Jim Hill:** Well, Holly, you're in luck because we have one of the world's greatest experts in the microbiome, and he's going to answer all of your questions. With us today is Professor Jack Gilbert. Listen to this closely. Jack is Professor of Pediatrics and Oceanography. We're going to ask him about that one. He's at the University of California, San Diego. There he directs both the microbiome and the metagenomic center. He's authored over 450 publications.

He wrote a book in 2017 called Dirt Is Good. I've gotten to know Jack over the past couple of years, and this guy really knows his stuff on the microbiome, and we're really lucky to have him here. Jack, welcome to Weight Loss And.

**Jack Gilbert:** Thanks, Jim. I'll try and live up to that praise. That's high.

**Jim Hill:** To start with, pediatrics and oceanography. Give us the cliff notes of your academic story.

**Jack Gilbert:** It's too long. I do whatever I'm interested in, which is a very privileged position to be in, but it just keeps me looking in different areas. Probably a little bit of ADHD.

I can't stay focused on one thing for very long, but I have a lot of fun. Being the world's first pediatric oceanographer is a position to be in. Also, in San Diego, you have to be connected to the ocean, man. The surf is real. If you're going to be in human health, you've got to be connected to the ocean. That helps.

**Jim Hill:** Love it.

**Holly Wyatt:** Well, welcome, Jack. I can't wait to be able to ask you some of these difficult questions, but let's just start out by what is the microbiome in simple terms and maybe a little bit of why you think it's important for our listeners.

**Jack Gilbert:** Yeah. I mean, we actually live on a microbial planet. I know that sounds weird, right? But for four billion years, this planet has been colonized by bacteria, small microorganisms that look very similar to bacteria called archaea, but are actually more similar to us as humans. And then lots of things like fungi and viruses, right? The things which you know about in your general day, but they colonize every single place on this planet, right? So anywhere you can imagine, microbes have found a way of living there. The bacteria, the archaea, the viruses, the fungi, they've done a really, really good job at colonizing this planet. And then a mere 500 million years ago, some of them combined together to make us, right?

For a 500 million year process. And eukaryotes, the all the things you can see with your eyes from the plants and the animals to us, they're just a combination of two different types of microbes that came together to make one giant multi-sailor microbe. So we really do live in a microbial planet and our bodies evolved in that planet. And so the microbiome is just all of the microbes, those bacteria, the archaea, the viruses, the fungi that have colonized your body. Your body's just another lump of flesh that's come along in the last five million years. And the microbes have figured out how to colonize you, like they colonized everything else in the planet from the savannah to the polar regions, from the depths of the ocean to the tops of the atmosphere. Your body is just another microbial ecosystem.

**Jim Hill:** Wow. That's something to think about. So Jack, people in the obesity field are very excited about the microbiome. How does or could the microbiome influence body weight?

**Jack Gilbert:** We can ask this in a quick way or a long way, but there's really just two very simple paths where the microbiome can influence it. Number one, microbes that live in your intestine. And remember, there's about 30 trillion cells of bacteria living in your gut. That's around one and a half pounds of bacteria living inside your intestine. They can change how much energy you extract from your food.

Right? So if you have about four or 500 different species of bacteria living inside your gut, so if you think about it this way, if you have the wrong four to 500 species, then they're going to be extracting tons of energy from your food. And they're going to be nowing your body to accumulate that energy as fat. If you have the right ones and you're eating the right kind of food, then they will help to regulate your metabolic energy. They'll help to keep down, you know, fat content will be lower.

You'll be burning more energy with the mitochondria, which the little powerhouses inside your muscles. And so it really comes down to that. Do the bacteria help to extract energy from your food or do they keep it normal?

And then the other one's really interesting. The bacteria in your gut can promote inflammation in your body, which changes how your body processes the food energy. So if you have a microbiome which promotes inflammation, then it can stop your body from processing that energy in a beneficial way and actually make you start to accumulate fat mass. And that can be annoyingly for people that can be using exactly the same number of calories that your next-door neighbors are eating and not putting on weight. But if you have the wrong kind of bacteria in your gut and you're eating the same number of calories, you can start to put on weight.

**Jim Hill:** That is interesting because we've always known that, that two people lift sort of the same lifestyle and have different results in terms of their weight. So this is beginning to help us understand why that might be the case.

**Jack Gilbert:** Yeah. I mean, the first time we figured this out was looking at twins. So, you know, identical, genetically identical twins can be discordant or different for obesity, right? So one can be obese, the other one can be lean. And we looked at the bacteria in their guts and they were different. And if you take the bacteria in the guts of these twins and you out of their gut, I mean, you collect their poop, which is a really good source of their microbes, and you stick that poop into the guts of mice, then an obese twins gut microbiome will make that mouse gain more for the same number of calories after the lean twins microbiome. So the microbiome itself can actually change the obesity of another species of animal, right?

When you take it out of your body and put it into a mouse, that mouse will gain more weight if you take it from an obese person. And so that means that the genetics isn't playing that much of a role. In fact, we can only predict whether you're likely to generate a become obese with about a 50-50 chance, a coin flip, right, based on your genetics. But your microbiome, we can predict your potential of becoming obese from your microbiome with about 85% accuracy, which is pretty amazing.

**Holly Wyatt:** Wow. So you're saying that the bacteria in our gut is more powerful in terms of predicting our weight than our genes? Absolutely. That's something to think about. So I want to back up one second, because I know some of the listeners may have caught this, because anytime you say something like bacteria may be using energy or getting rid of energy, they're going to go for that. They want to understand that. So are you saying that certain bacteria use our food or burn our food? How is that bacteria impacting the energy status? Not the inflammation part, but the energy part?

**Jack Gilbert:** This is really interesting, right? Remember, the microbes colonized your body. Why do they colonize your body? Especially why do they colonize the gastrointestinal tract, that donut hole that goes through your body from your mouth to your anus? Why colonize that bit? What's the benefit?

**Jim Hill:** Food.

**Jack Gilbert:** Precisely. You, as this walking, talking automaton, just keep on shoveling lots of lovely food into this hole in here and feeding them. They eat all of that food, especially the stuff that gets down really deep. Passes your stomach, passes your small bowel, gets into your large intestine, right? So that is really important. The food that you feed them changes which ones grow. Maybe you've got 500 species, like a rainforest, right? If you put the right kind of nutrients in, you're going to get different trees growing. If you put other types of nutrients in, you're going to get different trees growing.

**Jim Hill:** My microbiome may be different from Holly's.

**Holly Wyatt:** Oh, it is.

**Jack Gilbert:** Undoubtedly different.

**Holly Wyatt:** I eat what I eat, Jim, compared to what you ate. Oh, absolutely. It's different.

**Jack Gilbert:** Also, you know, depending upon, we can tell a woman's microbiome from a man's microbiome as long as they're menstruating, right? If a woman's menstruating, we can see the impact of the hormones passing through her body on the gut bacteria.

**Jim Hill:** I think it's all those salads they eat.

**Holly Wyatt:** Oh, Jim, be careful, Jim. Be careful. But interestingly, so then when women go through menopause, we know there's a change in hormones, but then that also may change the gut bacteria, the microbiome, which may be another reason why we see changes at that time.

**Jack Gilbert:** It is. That's really important. The postmenopausal microbiome of women looks more similar to a man's microbiome than it does to a premenopausal woman's microbiome. And it's actually associated with many of the side effects that we get during menopause, right? So everything from hot flushes to memory loss to discordant behavior. A lot of the physiological features can be linked to changes in the microbiome.

**Jim Hill:** So, Jack, here's the big question. And I ask you this because you and I've talked about it before. And when I talk to a lot of microbiome people, I just get totally confused. But you have been able to clarify that as much as anybody I've talked to. What is a healthy microbiome?

**Jack Gilbert:** It's context-dependent, to quote Vice President Harris. You have to be in the right context, right? That's really, really important. So what is healthy? A healthy microbiome is a microbial community.

This group of four have 500 different species of bacteria living inside your gut that does not cause disease or chronic conditions, metabolic diseases. So it will not cause obesity. It will not lead to cancer. It will not cause mental health issues such as depression. It will not cause inflammatory diseases like psoriasis or IBD or IBS.

So it's really important. It's a microbiome that does not cause disease. That does not mean that there is one microbiome that does not cause disease. Every country we go to on earth, people have different species of bacteria living inside their intestine. What's interesting is the functions, the metabolic ways those microbes live inside your gut is actually quite similar, but they see different species of organisms. So what we tend to say is that there's a microbial functional capability which lives inside our gut, which we think is beneficial for our health.

**Holly Wyatt:** Well, it's just so interesting to think about. So I heard what you're saying is prevention. There's certain bacteria that are good that don't produce disease. Is it true then you could change your bacteria or have certain bacteria that would actually treat a disease, would actually reverse a disease?

**Jack Gilbert:** It's very super interesting, Holly. From my perspective, I can't change your genome, right? Not easily. Maybe a bit of of tinkering I could, but I can change the bacteria that live inside your gut. One of the most successful ways of doing that is a fecal microbiome transplant where I take, for example, poop from Jim, I blend it up, put it inside your intestine, right? And allow his bacteria to colonize your intestine. Now, if you're sick and we can say that the bacteria in your gut might be contributing to that sickness, then swapping your sick bacteria for Jim's healthy bacteria could be beneficial and could help to treat disease.

**Jim Hill:** But is that short term or long term? Don't you still have to maintain that new microbiome?

**Jack Gilbert:** You do. So this is where it becomes really complicated because obviously what we said before, the microbiome is very dependent upon the food that you shovel into your pie hole, right? For example, if we wanted to stop obesity and your microbiome was obesogenic, i.e. it caused obesity, then we would have to change that bacterial community to one that did not cause obesity. And we could do that maybe by a fecal microbiome transplant from a lean person, maybe taking antibiotics to kill off certain bugs, maybe just changing your diet.

And that's where the problem comes in, right? The best way to lose weight is to change your diet and do a bit of exercise. The best way to change your microbiome is to change your diet and do a bit of exercise.

So they're the same thing. But I think it's kind of cool that you know why changing your diet and why doing the exercise might be influencing your body in this way. It might be influencing the microbes and influencing how much weight you can gain, right? That to me, I think is important and people should know it.

**Holly Wyatt:** So what diet then? This is because this is what I know what they're thinking right now. Okay, well, what diet do I need to be eating? If I want to lose weight, want to be lean, what's the best diet for that?

**Jack Gilbert:** Yeah, that's a complicated question because what we're finding out is that different people respond to the same diet in different ways. And the same microbiome can influence the diet in different ways.

So it's complicated, right? But the rule of thumb is you need to consume 30 to 40, ideally 50 grams of fiber in a day. Because fiber, dietary fiber in your food is one of the primary food sources which promotes the good bacteria to grow inside your intestine. And then polyphenols, right?

These you'll hear about them. They make all of the fruits and vegetables colorful, right? You know, like you see purple fruits and orange fruits. And these polyphenols can be incredibly valuable. They're another food source for the bacteria that live inside your body. And then avoiding things like simple sugars. Simple sugars are a food source for bacteria, but those aren't good bacteria. Those are bacteria which cause obesity and saturated fats, which aren't really consumed by the bacteria, but can actually change the immune system in your gut to promote the growth of bacteria which can cause obesity. So it's not like a bacteria consuming fat, but the fat changes their environment and then promotes the growth of bacteria which will make you fat.

**Jim Hill:** So Jack, I've heard you talk about this and talk about two things related to the microbiome. One is having the right kind of bugs and the other is diversity. Can a varied diet contribute to a varied microbiome and is that a good thing?

**Jack Gilbert:** Yeah, I think about it like in a farm setting, right? If you put one type of seed down and you like treat it with one type of fertilizer and one type of herbicide, you're going to get one type of plant out. You know, a monocrop, a mono, you know, just one type of maybe corn just growing in the field.

If you want to get lots of different species of plant growing in that field, you've got to treat it with lots of different seeds, lots of different types of nutrients, lots of different types of treatments to allow for a more diverse plant population to grow. Same as chewing your gut. You can't just eat lettuce, even though it's rich in nutrients and fiber. You can't just eat that one type of fiber and those one type of nutrients because you'll just get one type of micro growing. You need to eat lots of different species of plants.

We tend to say try and eat 30 to 40 different types of plants a week. Wow. Wow. That sounds hard, but it's actually not that hard. Just add up, get a diary, write it down, tell me how many plants you ate in a week and you remember a potato is a plant, broccoli is a plant, cabbage is a plant, you know, think about what you're…

**Jim Hill:** There's a challenge to our listeners. Keep a record over a week and see how many different kinds of plants you eat.

**Jack Gilbert:** And those different plants will feed different types of bacteria and you'll get a diverse array of microbes. And no matter where we go in the world, no matter which country we're looking at, no matter what type of person we're looking at, the people with higher diversity, more different types of species of bacteria in their gut tend to have lower rates of obesity, lower rates of cardiovascular disease, lower rates of depression, lower rates of neurodegenerative diseases like Alzheimer's and Parkinson's, lower rates of women's associated diseases. I mean, they just tend to go down. So higher diversity is generally better.

**Holly Wyatt:** I love this because this is another reason to eat vegetables. I mean, there's lots of good reasons to eat vegetables are plants, but this now even says, you know, to get this diversity of gut bacteria. So another reason to do that. So with all the hype about these new GLP-1 medications, is there any role of the gut, the microbiome in terms of satiety, hunger, food noise, anything going on there?

**Jack Gilbert:** Yeah. So if you consume a certain amount of fiber at breakfast, like if, let's say you had a granola with some yogurt and maybe some berries on it and that might have eight to nine grams of fiber in it. And let's say you threw an avocado on the side, that's another nine grams, maybe a small portion of almonds, that's another five grams. If you have that for breakfast, it sounds quite big like some fruit and some vegetables and some granola and some nuts, right? By about 11:30 to 12pm, you would not be craving between if you had that like seven a.m., between like 10 and 11 a.m., you would not be craving much food, right? Your cravings would be down.

Why? The bacteria in your gut take that fiber, munch it up, poop out another chemical called acetate, right? That acetate gets into your blood and it circulates through your body and it latches on to one of your endocrine, one of your hormone-generating organs. And that hormone-generating organ, when it sees the acetate will start pumping out a hormone called leptin. And that leptin binds onto other parts of your body, which make you not hungry. So the bacteria in the gut and the way they consume the fiber in your food will make you feel less hungry. And also, there's another chemical they pump out when they consume fiber called butyrate, which will also control your blood sugar after you're eating and control how much insulin your body produces.

So all of these drugs, these GLP-1 and GIT drugs, drugs that we're consuming, Ozempic, Tirzepetide, they work in a very similar way to the way bacteria work naturally in controlling how you're processing energy.

**Holly Wyatt:** Does it matter if it's soluble or insoluble fiber in terms of this pathway?

**Jack Gilbert:** It has to be soluble. So, most of the dietary fibers that we find are soluble fibers, right? Some insoluble fibers can be consumed, but they're not easily accessible. So, we actually see a lot of the soluble fibers that we find in fiber supplements. The reason they work is because they feed the bacteria in your intestine and they help to reduce inflammation, promote a healthy body.

**Jim Hill:** Yeah, Jack. Holly and I talk a lot about exercise and while you don't have to exercise to lose weight, what we find over and over, it's one of the best predictors of weight loss maintenance. How does exercise affect the microbiome?

**Jack Gilbert:** So, it's a really interesting relationship that actually stems, goes back about 500 to 600 million years ago. So, are you ready? I'm ready. So, around a billion years ago, two microbes came together. One consumed the other and when it didn't consume it and kill it and digest it, it consumed it and harnessed it and started to use it to start to produce energy. And forward another billion years to where we are now and every single one of your cells, except your red blood cells, which is interesting, contain little organelles, little organs inside them called mitochondria. And those mitochondria are the remnants, the evolved remnants of those ancient bacteria that were consumed by the other microbe a billion years ago. Those ancient bacteria still speak the same chemical language that your bacteria in your gut speak. So, they can actually communicate with each other chemically between your muscles and your intestine.

And when you exercise, the mitochondria in your muscles pump out chemicals into your bloodstream, which leak into your gut and actually stimulate the growth of different types of bacteria, who pump out their own chemicals, which go into your bloodstream and communicate back to the mitochondria and promote mitochondrial activity.

**Jim Hill:** I love this.

**Holly Wyatt:** But they all communicate and we didn't even know it.

**Jack Gilbert:** Yeah, we're just a host to an entire little village that's all having a chat. And when you exercise, the conversation is actually beneficial. It can reduce inflammation. It can also promote the growth of bugs in your gut, which help to regulate your insulin levels, your blood sugar levels, your satiety levels and also reduce the chance of developing obesity.

**Jim Hill:** So, Jack, I love to put stuff together. Let me run this by you and tell me if this makes sense or not. So, people looking at body weight regulation oftentimes look at what you eat or your physical activity level. But Holly and I feel like your metabolism is very important and your metabolism differs from person to person. I see the microbiome as a big part of your metabolism. In the weight loss field, there's this concept of a flexible metabolism. And a flexible metabolism is one that quickly adjusts to the source of fuel your body's using. You go from fed to fasted to exercise. And a flexible metabolism can quickly adjust to that. The other thing that we think a flexible metabolism can do is when you do over-indulge, it makes it less likely that you're going to have negative effects of that. So, when you over it, you store a little less. And we think that over time, this difference can really be the difference between susceptibility to obesity and using your body to help resist obesity. Does that make sense?

**Jack Gilbert:** Not only does it make sense, but I can describe it from the microbiome's perspective. So, we did a very large experiment where we noticed that most people, when they try and lose weight, they end up putting on more weight and becoming heavier than they were at the beginning of the weight loss program. We call this the yo-yo effect, right? It just keeps on going.

We talk about that all the time. We found that you can control that in animals, in mice, by manipulating the microbes in their gut. So, if you have the wrong kind of bacteria in your gut, they hang around for quite a time, right? If you have the wrong kind of bacteria in your gut, then they will actually help your body to rapidly regain weight when you fall off the wagon and consume a couple of hat-rows.

**Jim Hill:** Because you're extracting all that energy from the food.

**Jack Gilbert:** And also, how they chemically modify your body will alter your metabolic response to that food. Though, this is interesting. If we put those mice on a diet for three months, which for a mouse is about the equivalent of a year's worth of our life, right? You put this mouse on a diet for three months, you can eradicate the presence of those pro-obese bacteria.

Think about it like this. If you put the bacteria on a mouse on a diet, which starves those bacteria, doesn't provide the nutrients they need to survive, they will eventually starve and die out. But it takes around about a year on your diet to kill them off. When you get to that point where those bacteria are dead, right? Then, if you ate a hamburger, you wouldn't immediately rebound in your weight gain. That's where you get that flexible metabolism.

**Jim Hill:** See, Holly, that fits exactly with what we're saying. You don't see it in a steady state, but you see it in a disruption. It gives you, you're going to store a little less. I'm telling Jack that a typical person, Jack, might consume a million calories in a year. Body weight regulation means that you have to be super, super accurate.

It's hard to believe you do that by adding up and taking expenditure. Your metabolism is this thing that helps you do that. Even becoming obese, it's like your accuracy goes from 100% to like 99.4% or something. It's a small, small difference, but it makes total sense that the microbiome is underlying this ability to help match your intake to your expenditure.

**Jack Gilbert:** One thing you'll love is that if I take animals and I remove all the microbes, so these animals have no bacteria in them. They're called germ-free animals. Think of the boy in the bubble back in the 1970s and 80s, this kid who couldn't be exposed to microbes. But this is an animal which is completely sterile.

I mean, literally has nothing in it. I can feed that animal a high-fat, high-sugar, McDonald's diet daily, daily, daily, bam, bam, bam. Or I can feed it a high-fiber, high-polyphenol diet, like a really healthy salad diet. As long as I'm feeding it the same number of calories, the weight gain in the animal will be identical. But if I put microbes back into that animal and populate or repopulate its gut with bacteria, and I feed it exactly the same food, the animal eating the high-fat, high-sugar diet will gain approximately 80% more weight over the same timeframe as the animal eating the high-fiber diet. So the bacteria in the guts of these animals are actually mediating how much weight you're going to gain when you eat that unhealthy diet. And also your metabolic response to that diet. In the absence of bacteria, we don't see that response. You need to feed the bacteria in your gut to get the right microbial community growing, and that will help to protect you from metabolic disease, cardiovascular disease, mental health diseases, et cetera, et cetera. And you need to understand that. It's not just what you eat. It's what you eat and how it affects the bacteria in your diet.

**Holly Wyatt:** I love this because it's showing a way that, yes, metabolism is different, but it's different through this pathway of bacteria. And you can change it. And that's a really different way. Yeah.

**Jim Hill:** Well, that's the beauty is you can change it. Genetics, you can't change.

**Jack Gilbert:** And metabolism, for me, has always been kind of like, it's metabolism. What do you mean, yeah? Whereas the microbes, it's so obvious, right? If I feed the right kind of bugs, the right kind of food, I will control my metabolic response to food.

**Holly Wyatt:** Yeah. I love this. I was a microbiology major, so I'm going to take credit somehow or another for some of this, because this is what I studied when I was an undergraduate. But here, here's the next question. Okay.

So why do I need to eat to get this good bacteria? I know that you, I think people are now going to be saying, okay, I'm buying into this. We're believing him. He's got us. He's got us going. But let's put some, what I call, pie on the plate. Tell me what to eat.

**Jack Gilbert:** What do I eat? I eat at least 30 species a plant a week. Don't really consume much fine sugar, right? I try and, I try to eradicate most of that from my diet. I fall off the wagon occasionally. I love milky ways. Those are amazing.

**Jim Hill:** But if you have a flexible metabolism, you can do that occasionally.

**Jack Gilbert:** If you do it periodically, like, you know, now and again, sure you can. If you were to consume one a day, then it would, it would stop. Right. Generally, my average breakfast is, so maybe two egg omelet with vegetables in it for breakfast. I might snack on some almonds during the morning.

If I'm feeling a little bit peckish, maybe 20 grams of almonds, like five or six almonds. And then maybe for lunch, I'll have a salad and maybe I'll put a bit chicken on it. But invariably, it'll just be a vegetarian salad, even though I'm a meat eater.

And then I might again, snack on some nuts for my afternoon snack. If I'm working a bit late and I'm not going to get dinner early. And then for dinner, I can really vary. Like, generally, I can eat pretty much whatever I want for dinner. But I nearly always try and have at least two or three portions of vegetables on there. Try and make sure that if I do have meat, like a steak or chicken, it's quite lean, but I try and eat it, you know, like trying portion control. But I eat a lot of fish. And fish is really good, really high in protein and nutrients and really low in saturated fat.

So that's always good. But yeah, rule of thumb, keeping many plants getting in your gob as possible. Fruit, vegetables, just keep on piling them in.

And then, try and reduce the amount of other things you can see. You should also try and there's one really cool study that came out about fermented foods. So people who try to increase their fiber intake suddenly, right? So let's say you've been eating hamburgers and hot dogs, mac and cheese, et cetera, and you suddenly switch to a high fiber diet, you're going to get bloating, you're going to get abdominal pain, you might get diarrhea.

You're going to feel uncomfortable for quite a long period of time, maybe two or three weeks. But people who actually did a transition phase where they started consuming more yogurt, more kombucha, maybe some kimchi, maybe some sauerkraut, right? There's some fermented products, fermented food. They started consuming that for a period of two or three weeks and then started to ramp up the amount of fiber in their diet, got no gastrointestinal problems. And we found that that can boot the fermented food, can actually increase the diversity of bacteria in your gut.

Why? Because it's rich in nutrients that were products of the fermentation which the bacteria consume. So you can now grow the diversity of your microbes. And also it's usually got live organisms in it, which stimulate your immune system. Probiotics and live organisms in food, they don't usually survive and grow inside your body, but they stimulate your immune system and they keep it healthy, right? And your immune system's like the gardener that controls your microbiome. So that fermented food stimulates your immune system, creates a positive environment, pumps or lose nutrients into your gut, grows this nice, diverse garden of bacteria, and then those bacteria are ready for the onslaught of 40 grams of fiber a week. So you need that transition, right? You can't just switch your diet and hope for the best.

**Jim Hill:** Wow, we've covered a lot, Holly.

**Holly Wyatt:** Yeah. A lot of stuff to think about. I am already wanting to try some things out. I like the idea here, you talking about nuts and vegetables and all of that. For those of us who struggle with our weight, I mean, we have a pretty big appetite, you know?

And I think appetite, different people have different types of appetite. I always worry when people say, let's eat seven nuts, because I'm going to just tell you, Jack, I never eat seven nuts. Seven nuts is never enough for me.

So, and nuts are high in energy density, meaning a lot of calories, even though they have fiber. And so that type of thing always worries me a little bit, is I don't want necessarily all my patients out there going handfuls of nuts, you know? So have you had a weight problem? Is this in your past?

**Jack Gilbert:** It fluctuates. I fall off the wagon just like everybody else does. And so my weight balloons, the heaviest I've ever been is about 215 pounds, which isn't huge. But I'm six foot tall, but it was, it was, I was definitely in a, an obese state, very significant obese with a BMI of a little over 32.

So that's a problem, right? And I suffered immune related effects to that. So, you know, joint pain, started to get arthritis in my hands. And now I'm nearing 50, I start to have difficulty controlling my belly fat, which is a very negative indicator of cardiovascular disease.

And I have a lot of cardiovascular disease in my family. So I'm paranoid about that. So I do try and control it, but it is hard. It's hard. Right? So what do you do? Ozempic and Trizepatide and all these GLP1 medications that are out there and available, all they do is stop you from craving that food. You know, also stops you from craving that food and eating too many things is having a high fiber, high polyphenol diet.

**Jim Hill:** I love it, Holly. I love it.

**Holly Wyatt:** No, I agree.

**Jim Hill:** Because that's what people want, I think.

**Jack Gilbert:** I can eat a handful of nuts and that's how it stops.

**Holly Wyatt:** So it's like, get the appetite under control first and then portion size, it becomes easier.

**Jack Gilbert:** Yeah. You can't do is have this like massive meatloaf and fries dinner and a bowl of sugary cereal and then a sandwich, that's rich in fats and sugars for lunch and throw some nuts in the middle. And you can try, you can try, might help, but on the whole, if you're eating, I think you've made it worse.

**Holly Wyatt:** You probably made it worse at that point.

**Jack Gilbert:** Right. You might not, it's really hard to tell, but at the end of the day, it's in a background of poor nutrition. If you've got poor nutrition already, a patches on it don't work. You have to fundamentally overhaul it. And trust me, I know how hard that is. I fall off the wagon. And so I always say, do as I say, not as I do.

I also say it's really easy to bring a horse to water, but you can't make it drink. Nutrition and diet is a sociological and psychological thing. It's not something that is easy to do, right? And that's something we, we as scientists really struggle with, but it's, it's really hard to make people eat healthy. And I know that from first-hand experience.

**Jim Hill:** So Holly, Jack's already covered the personal vulnerability without us asking. He's already told us. So he took away our surprise questions. Let's take a couple of reader questions and then sum up.

**Holly Wyatt:** Yeah, some listener questions. So you want me to take the first one, Jim? You take the second one? Yeah. So one of them we got, and I get this one all the time. So there's, this has been actually for multiple people, but from Jerry, should I be taking a prebiotic or a probiotic for my gut health? Which one's better?

**Jack Gilbert:** Prebiotic. But realistically, so a prebiotic is just a nutrient which feeds bacteria. So fiber is a prebiotic, right? Anything with fiber or polyphenols in it stimulates the growth of bacteria in your intestine, good bacteria, right? And so a prebiotic can be very beneficial. But a probiotic is, as I said, most probiotics do not colonize your intestine.

They cannot grow there. They will die and they will just be pooped out, right? 99.9% of them that you buy on the stores do not colonize your intestine, right? Which is the reason you need to take them all the time. What they do do is they stimulate your immune system and make the immune system in your gut healthier for the bacteria that live there.

And that can be beneficial. If you, I like to think of it as for thousands of years we ate fermented foods because we didn't have refrigeration and that fermented food had bacteria in it and your immune system got used to seeing them, right? So if you're not eating a lot of fermented foods now, you can consume probiotics because it's doing essentially the same thing as those living organisms in the fermented food. It's like swapping it out.

**Holly Wyatt:** So the probiotic, you're really drinking or eating the bacteria themselves and you're saying that they go in but they don't stay there. That's why you got to keep doing it. Does it matter what type? I'm always looking at it says it got this many of this type of bacteria and this many of that type of bacteria. Do we care?

**Jack Gilbert:** There are a lot of double-blind placebo controls, clinical studies, randomized that have been demonstrated to show that some probiotics do lead to health improvements. But if you're not sick, it's really hard to know. So I say, pick the cheapest one that you can find and consume it. If you don't want to consume fermented foods, you can consume probiotics and they may have a similar effect.

**Jim Hill:** But you can do it through fermented foods too.

**Jack Gilbert:** Fermented foods will be way better because foods also come along with all of those prebiotics. So for me, it's like prebiotics and probiotics combined and they're often a lot cheaper than the probiotics by themselves.

**Jim Hill:** Okay. Jack, Leslie asks, is there a test I can take to see if I have a good microbiome?

**Jack Gilbert:** This is a question I get all the time and Holly, you alluded to it in the beginning. It's really hard. A lot of companies out there will tell you that they can say what if your microbiome is healthy.

The difficulty, as I said, it's context dependent. So I can say, yeah, you have some bacteria in your gut that might be associated with disease or you have some bacteria in your gut that might be associated with health. But giving you a score which says, yes, you are healthy and you are not, is very, very difficult to do and is a very flawed way of thinking about it. It's like saying that forest over there is a healthy forest and that forest over there is unhealthy. They might be both healthy but looking very different depending upon the conditions that they exist in.

So it's very, very hard to do a test to do that. So I would say, listen to your body. Listen to your poop, if you will. Are you pooping nice big, firm stools that are soft enough and you're pooping them and you're quite regular? That probably means your gut microbiome is very healthy. Do you have any gastrointestinal bloating? Do you have any pain? That probably means that your microbiome is unhealthy. Do you have diarrhea and constipation? Unhealthy. Find a way of consuming food that will help your body feel better. It's a shit ton better than consuming, pun intended, than consuming or doing tests that may not tell you anything.

**Jim Hill:** Wow. Holly, this has been fabulous. Jack, what you have told us, I think reinforces what we've already been looking at in terms of the role of a body's metabolism and this helps us understand why the microbiome is such an important part of that. Holly, to summarize what I would say is the microbiome clearly affects body weight. I think from what Jack told us, it's almost impossible to maintain a healthy body weight with an unhealthy microbiome. A healthy microbiome can help you in so many ways avoid weight gain and obesity. A healthy microbiome differs in different people, but the best advice you can get is to consume fiber. Fermented foods are good. A diversity of intake is good. Jack suggested we try to eat 30 plants a week and we challenge people to see if you're doing that. I'll end in exercise.

I think exercise can really affect that. Part of what we've learned is understanding why some of the things that we've seen to be the case are the case. That's why the microbiome, in my view, really helps us understand the why of some of the things that we've observed, Holly.

**Holly Wyatt:** I agree. I think it's taking some things together that we haven't really been able to understand how they may be hooked together, how they're communicating, why they do what they do. I really want to go back and think about some of these things because I think this is really interesting and I think really hopefully pushing the field forward in a good way.

**Jim Hill:** Jack, thank you. This has been a wonderful conversation. You've taught us so much and we really appreciate your time.

**Jack Gilbert:** My pleasure. Thank you very much.

**Jim Hill:** We'll talk to you next time on Weight Loss And.

**Holly Wyatt:** Bye, everybody.

**Jim Hill:** 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.

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**Jim 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.