When Should I Worry About...

PODCAST: Why Metabolism Goes Haywire & What's In Your Control

March 12, 2024


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It's been called the most common and serious condition you've never heard of. Metabolic syndrome, which afflicts an estimated 1 in 3 U.S. adults, occurs when the body's metabolism is disrupted, increasing the risk of heart disease, stroke and diabetes. Why is it on the rise? What triggers it? And how can you boost your natural metabolism to prevent the condition? In this week's episode, we talk to an endocrinologist about why some people can eat so heartily without gaining weight, how much of metabolism is genetic and which groups are most at risk of developing metabolic syndrome.

Expert: Dr. Laila Tabatabai, Endocrinologist

Interviewer: Todd Ackerman

Notable topics covered:

  • Is a fast metabolism always preferable to a slow one?
  • The surprising ages when metabolism slows — and doesn't slow
  • The counter-intuitive effect of starvation diets on metabolism
  • Should doctors more routinely test patients for metabolic rate?
  • Whether pills that claim to boost metabolism work
  • The ties between fertility and metabolic health
  • The cluster of risk factors that indicate metabolic syndrome
  • Insights from metabolic health research that can help people shed weight
  • Best exercise for speeding up metabolism — aerobic or strength training?
  • The best diets to prevent metabolic syndrome
  • Why middle-aged women have a harder time losing weight than men


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Episode Transcript

ZACH MOORE: Welcome to On Health with Houston Methodist. I’m Zach Moore. I’m a photographer and editor here, and I’m also a long-time podcaster.

TODD ACKERMAN: I’m Todd Ackerman. I’m a former medical reporter, currently an editor at Houston Methodist.

ZACH: And Todd, how do often do you think about your metabolism?

TODD: Probably not that often just because I think I’ve been blessed with a pretty good, pretty fast metabolism. I’ve always been thin my whole life. Parents were not heavy. I stay active, eat pretty good. So, I think I’m kind of the definition of fast metabolism, lean body type.

 ZACH: Sounds like that’s a mix of like, just good habits, good genes and then…

TODD: Luck.

ZACH: Yeah.

TODD: Mostly luck.

ZACH: [Laughing]

TODD: But I’ll take it.

ZACH: So, have you ever had a metabolism test?

TODD: I haven’t. And so, I don’t really know for sure if I have a fast metabolism.

ZACH:  I have had a metabolism test.

TODD: Tell me about that.

ZACH: I was getting into my early 30s. I thought maybe my metabolism was going down. I was like, “Well, I’m starting to gain weight and maybe that’s why. You know, maybe it’s not my fault. But I was surprised to find out that not only did I not have a slowing metabolism, my metabolism -- my resting metabolism was actually faster than normal. So, I really have no excuse. I was very disappointed to hear that.

TODD: Really?

ZACH:  Yeah.

TODD: That would seem to be good news and then it’s something in your control.

ZACH:  Well, exactly, right? Depends on how you look at it. Because, like, well now it’s all on me.


I can’t blame bad luck or genetics. It’s like, “No that’s on you, man.”

TODD: But you can do something then. If it's bad luck, then you know, if it's genes, then there's not a whole lot you can do.

ZACH: No, that is an encouraging way to look at it.

TODD: Yes, that’s how I would’ve looked at it.

ZACH: The glass half full mentality. I respect it. But that was surprising to me because, you know, I think that we -- there's this general consensus in people where if they think about their metabolism, they think, “Oh, as I get older, it slows down.” And that's true to a point, but it's not as cut and dry as that. And that's part of what we're talking about today.

TODD: Yeah, mine, I'm sure has slowed down from what it once was. During the pandemic, I was very either sedentary or supine for a while before I started walking. The gym had closed and so I wasn't getting my usual exercise. And, I did find myself putting out a little weight there. So, I have noticed at some point my metabolism, it just seemed like working out was a little harder. I think it's changed, although I still think I'm doing pretty well with it. So, this has become, a kind of buzzed about topic these days, metabolism, metabolic health, metabolic syndrome, which is a constellation of heart related issues like, high blood pressure, high blood sugar, high cholesterol, and waist circumference. It’s expanding. I think it's estimated that's something one fourth to one third of people now might suffer from metabolic syndrome.

ZACH: Wow.

TODD:   It's something doctors are increasingly talking about with their patients.

ZACH: Hmm. Well, speaking of, who did we talk to today about this, Todd?

TODD: We talked to Dr. Laila Tabatabai who's an endocrinologist at Houston Methodist, and who has a keen interest in this subject.

[ Sound effect indicating start of interview]

TODD: Welcome Dr. Tabatabai. How are you today?

DR. TABATABAI: I'm well, how are you doing?

TODD: Good. I'm looking forward to this discussion, which is about metabolism, metabolic health, metabolic syndrome. Those are not new terms, but it seems like there's a greater focus on 'em these days. Is that right?

DR. TABATABAI: Absolutely. Absolutely. I think unfortunately our society has become more overweight with time. So, obesity and syndromes of excess weight are much more common in western society and other societies across the world that are now becoming more western. And by that, I mean there's much more of a focus on processed food. We are a much more sedentary society. We no longer need to engage in physical activity for a lot of our activities of daily living. So, that's been -- that's just a fundamental change, I think, in the way that we live in the world today. So I think for that reason, patients and physicians, really everyone is focused on metabolic disorders now.

TODD: Just to start, talk to me a little bit about what metabolism is exactly. Often, I’ve heard people say you have -- someone has a fast or slow metabolism. Never exactly sure what that meant.


DR. TABATABAI: That's a great question. So, metabolism means a lot of different things to different scientists and to different physicians even. So, essentially cellular metabolism is very different from what you and I might think metabolism to be in terms of at what rate does the body burn calories and utilize energy, essentially calories, kilojoules, these are all just measurements of energy that are expended by the body to support all of the vital functions. So, circulation of blood, ventilation or exchange of oxygen, all of these various things. Now, cellular metabolism on the other hand, is very different and it involves different molecules and ATP, which is Adenosine Triphosphate. And that's the key, actually, to cellular energy. So, it depends really who you ask, what metabolism is. But I think most of us have come to understand metabolism as a process by which we basically take in nutrients and nutrient dense foods and convert them into macronutrients that our body can then utilize in cellular processes. So, if you think about nutrients like proteins, carbohydrates, and fats, those can each be converted into forms of energy that the body can utilize, and some are more efficient than others for energy processing and some are more efficient than others for energy storage. That's kind of a little mini summary, if you will, of a really, really broad topic.

TODD: Okay, very good. Is it better to have a fast metabolism?


DR. TABATABAI: So, that really depends on who you ask because a fast metabolism, you know, some would think is a great thing. It means that you can consume larger quantities of food and metabolize the calories and energy more efficiently, thereby you have a lower risk of gaining weight and storing fat. But it's important to remember a fast metabolism could be for pathologic reasons. So, there are some disease states that consume a lot of calories, for example, cancer, when there are unchecked cells growing, that's actually a fast metabolic process happening. And that's why cancer patients, for many reasons, but among them, that increased cellular metabolism because of undivided cell growth leads to cachexia or severe weight loss in cancer patients. Cystic fibrosis is another condition where it affects the lungs and oxygen transfer and infection risk. And those patients generally are very, very lean and they have to consume huge amounts of calories in order to support their body's life processes. So, it can be a good thing when it's sort of looked at as the propensity to remain lean and you know, not have to quote/ unquote “worry about one's weight,” but it's not always a good thing to have a fast metabolism. The other thing just to note is certain conditions cause a fast metabolism. And even though they might not be as serious as cancer or cystic fibrosis, they do need to be treated. So elevated thyroid, for example, Graves disease or hyperthyroidism, that causes a fast metabolism. So, one of the earliest signs is weight loss, but that elevated thyroid level also causes rapid heartbeat. It can lead to heart damage and heart failure over time. It can lead to bone loss, a lot of other really negative consequences. So, all of that to say, I think unexplained weight loss is always something that should be checked out and it should not be chalked up to a fast metabolism unless you've always been that way. So, it's important, you know, not to look at weight loss as a good thing for everyone, ‘cause it's definitely not.


TODD: Now, I also hear high metabolism or bad metabolism. What are the proper terms you should be using about one's metabolism?


DR. TABATABAI: So, the interesting thing about the metabolic rate is that there really is no optimal range that's defined for humans because it's extremely individualized on the basis of the patient's size, height and weight, and their muscle mass, and potentially other factors like heredity, ethnicity and so on. So, we don't really have a way to measure someone's metabolism and say, “That's great. It's an A+. No need to work on anything.” What we can do is measure a person's metabolic rate, and we term that the basal metabolic rate or resting metabolic rate, it's sometimes called. And that is a way to measure how many calories, meaning that measurement of energy, are utilized by that person's baseline bodily function. So, if your resting metabolic rate is 1,500 calories, then any activity you do on top of that, whether it's just walking to and from the car, typing on a computer, or it's strenuous exercise and weightlifting in a gym, all of the additional activity you do is added on to that resting metabolic rate. And so that's the part that we can control because it involves staying active and fit and healthy. But it's also important to note that eating increases your metabolism. So, it is true that starvation or going extremely long periods of time without eating does actually reduce the resting metabolic rate. And that's in order to conserve calories, because the body really doesn't know that we're in 2024. Your body is, you know, stuck in the prehistoric stone ages. And so, if we have a lack of food, the body sees that as famine, and it will start to reduce caloric expenditure and shut down essential processes. So, fertility is actually very much linked to metabolism. And both in men and women, fertility can be affected by heavy dieting practices, crash dieting, so to speak, rapid weight loss and other health conditions that affect the metabolism absolutely affect fertility. So, understanding the factors that affect your metabolism and how you can possibly change those to be favorable is important.


TODD: Prolonged periods of not eating is, is generally not a good thing?


DR. TABATABAI: So, that's a great question. Intermittent fasting is actually a big buzz word these days. A lot of people are successfully using intermittent fasting to lose weight. And what's important to note is intermittent fasting is not the same as starvation. Intermittent fasting allows you as the patient, as an individual to decide how many hours a day you're actually gonna consume calories in the form of food. So many of my patients who've successfully done this will do a 16 and eight split. So, for 16 hours of the day, they do not consume any calories in the form of solid food, and then eight hours of the day they allow themselves to eat healthy meals, snacks, whatever it might be, and then the rest of the time they will just consume, typically, ideally, low sugar beverages, water, maybe sports drinks, chicken broth, you know, different types of broth, bone broth. But the key is to stay very well hydrated but restrict your caloric intake to those possibly eight hours a day. I think the most restrictive I've seen, which I think is a little bit too much, is, you know, 20 hours of fasting and four hours of caloric consumption. What that essentially does is, it's very successful for weight loss because you're just restricting the hours in the day that you can consume calories. So, for many people that just simplifies it. You don't need to count calories, you don't need to necessarily, measure out or weigh your food. You're just only letting yourself eat between certain hours of the day. And then when your time's up, you go back to fasting. Now, the reason that doesn't cause a shutdown in metabolism is that there is a predictable amount of caloric intake that's happening and it's happening at a predictable interval. So, you know, that really prevents patients from going into sort of prolonged ketosis, which can cause headache and other problems like brain fog and fatigue. It consistently lets them come under their resting metabolic rate and therefore their body will burn excess fat, hopefully, to meet that energy imbalance that they're experiencing.


TODD: So, there is a test to know your metabolic rate. Is that widely employed? Do most patients get that at some point, or just if they're having weight issues, they've asked for it?


DR. TABATABAI: That's a great question. So, metabolic rate testing isn't really a standard healthcare offering in terms of what a cardiologist or endocrinologist or primary care physician might routinely order. There are ways to do so accurately. The most accurate way, you know, has been to get into a sort of contraption that measures all of the carbon dioxide that's produced by the body over a set amount of time. And then that can tell you exactly the number of calories that the individual has burned. There have been some studies done in patients on ventilators in the hospital because we can actually measure that carbon dioxide production as well and, you know, very accurately gauge that person's metabolic rate. Now for practical purposes, what we really typically need this information for is, as you said, individuals who are trying to lose weight or want to understand what their body's basic needs are in terms of caloric intake. And so, there are ways to do that. They're typically available at nutritionists’ offices. Sometimes, even health clubs and gyms will offer this metabolic rate testing. There are ways to do it now that do not require, you know, as much equipment. But essentially, it gives a fairly accurate, you know, within plus or minus 50 calories how much the resting metabolic rate is.

TODD: Does it fluctuate much during the day?


DR. TABATABAI: There is for most people an increase in metabolism that happens early in the day and there are hormones in the body that begin to rise in the morning. Cortisol is among them, insulin, and others. And so metabolic rate for most people, begins to rise in the morning and peaks somewhere in the late afternoon hours and then the metabolism starts to come down in preparation for rest and sleep. Now for nocturnal workers, you know, anyone who's a shift worker, especially in the hospital, quite commonly those rhythms can be shifted because it has to do with your sleep wake cycle. So that can actually be completely reversed if you're on nights for a prolonged amount of time. And this is true for any kind of individual who might work overnight hours. But essentially, your metabolic rate matches the period of time that your body would be most active throughout the day. And the issue with that is many of us have sedentary jobs now, and so that activity level is just not there throughout the course of the day, and therefore the metabolism, the natural shifts that happen are not happening either. So, that's why it's important to schedule exercise, to have regular walks and things like that because prolonged periods of being completely sedentary is detrimental for the metabolism.


TODD: Short of an actual test, are there clear signs someone can look at that, whether or not they have a fast or slow metabolism?


DR. TABATABAI: So, typically speaking, people with the highest metabolic rate tend to be quite lean and have high muscle mass. And so that leads me to talk about something that might actually be more beneficial for people to measure or request having a measurement. And that is body composition. So, I'm actually an osteoporosis specialist and so I read bone density studies all day long, and the bone density machine is actually capable of doing a whole body composition test. And the reason it can do that is adipose tissue or fat, muscle, and bone all have different densities. So, it's possible with a simple x-ray test really to tell the density of these individual tissues and quantify it. So, when you do a body composition test, you can pretty much determine, fairly accurately what someone's lean body mass is. And by that we really mean muscle tissue. And the higher your muscle mass and the lower your body fat percentage, the higher your metabolic rate. Muscle is a more metabolically active substance than either adipose, connective tissue, or any other tissues in the body. So, it's really important to note that the number on the scale can be misleading, and I think a lot of people would agree with that because it can be reflective of fluid gain or bloating after eating high sodium. And most importantly, it may not actually reflect the body composition change that you're undergoing, especially if you're trying to eat healthfully and increase weight training, which are really great ways to try to improve your metabolism and lose weight. Those may not translate directly into pounds lost on the scale. Because if you are losing fat mass but gaining muscle mass, then you may look like you're losing very little weight or maybe none at all. So, measurements are actually a much better way to go. And waist circumference in particular is a great way to gauge how you're doing in terms of weight loss goals. Because a lot of the visceral fat that we all have, it can be in excess in overweight or obese individuals. So, that abdominal or waist circumference is a great way to see, are you actually losing inches and losing that visceral fat component.

TODD: How much of metabolism is just genetics and how much can you change?

DR. TABATABAI: So, I truly think that a large proportion of our metabolism is genetically set, and the reasoning for that is it depends on your body habitus, the size of your frame, the amount of muscle that you carry.

TODD: What was term? Body habitus?

DR. TABATABAI: Body habitus.

TODD: What do you mean by that?

DR. TABATABAI: Body habitus is really sort of a way to characterize somebody's height and weight very roughly. So, when as physicians we're examining a patient, we use the term body habitus sometimes to indicate if we're able to complete an exam or make certain physical exam findings, perhaps the body habitus prevents us from doing that. So, typically...

TODD: It’s like your natural build would you say?


TODD: Okay.

DR. TABATABAI: Natural build, certainly excess weight and obesity plays into that too. You know, it's something that I don't think BMI captures or even height and weight capture, because you can have somebody six foot, 200 pounds who's extremely lean and athletic and could even be an elite athlete. And then you could also have a six foot, 200 pound person who has very little muscle mass. So, the body habitus of those two individuals is very different. So, that's just a term that we sometimes, you know, use in the medical world.


TODD: So the, besides genetics, the major influences are pretty much diet and exercise?


DR. TABATABAI: Pretty much so. I think, as far as things that one can do to change one's metabolic rate in a safe way, really, nutrition choices and activity level, especially the type of activity which we'll talk about, those are two of the best and safest ways to change your metabolism. And I say that because there are so-called metabolism boosters. There are various stimulants that are actually used in certain medical conditions that can raise the metabolism and sometimes that can actually be a negative thing, and it's actually a side effect that the medication has. And so, we typically do not recommend long-term usage of metabolism boosters because they do carry risks. Anything that increases metabolic rate also runs the risk of increasing cardiac demand and heart rate, blood pressure, things like that could be affected. So, it's really why there's never been a magic diet pill in terms of metabolism. In fact, many years ago, I think in the 90s, there were some really high profile sort of diet pills that were available and they actually led to some cardiac deaths in different individuals. Those metabolism boosters, different herbs, they might even be “natural,” quote /unquote, they can be very dangerous in certain individuals. So, we really in the medical community, try not to recommend any sort of supplement or herb or metabolism booster pill because those really have not been shown to be effective long term and they can be quite dangerous.


TODD: Let's talk about the different types of diet and exercise that are good for improving your metabolic health.


DR. TABATABAI: So, in terms of diet, I think it's clear that any extremes are really not good and not sustainable. So, by that I mean extremely low carbohydrate diets or extremely high fat diets. These can be attainable short term, but the vast majority of my patients will not be able to sustain that specific diet plan long term. And then when they come off it, they experience weight regain. Oftentimes it's a lot of fluid, because when you cut carbohydrates, you also lose some fluid weight along with fat mass. And then consuming carbohydrates allows both water and fat to come back on. And it's really, I think more than anything, it's demoralizing to the patient, you know, to the individual who has worked really hard to lose weight and stick to a really stringent diet, and then to see that weight come back just by coming off for a few days, is really not good both physically and mentally. So, I think the most important aspect of a healthy diet is to maintain moderation. So, desserts and possibly alcohol, snacks, different things, these should all have a place in one's diet. The 80/ 20 rule is something that a lot of my colleagues will mention to their patients, which is 80% of the time we want you to follow a diet that's high in lean protein, vegetables, whole grains, and healthy fat. And the other 20% of the time you can indulge and you know, have foods that maybe do not have a very high nutritional value, maybe indulge in a few drinks or desserts. And that sort of balance allows you to maintain a healthy diet long term without getting deprived because the binging cycle or coming off of a diet cycle is really perpetuated mostly by a sense of deprivation and patients not being able to keep up to something that's very stringent. Now, as far as diet plans, a lot of physicians are kind of standing behind the Mediterranean diet, because that really has withstood the test of time and is associated with lower rates of heart disease, hypertension, hyperlipidemia, and other cardiac problems. So that would really entail, lean protein and really very little red meat, mostly fish and some poultry and then a lot of vegetables and some fruits, complex whole grains, complex carbohydrates, and then also some dairy which has both calcium and protein in it. So that sort of a diet I think satisfies a lot of our nutritional needs and also includes healthy carbs. So, there isn't that sense of deprivation either. And it seems that, you know, following a mostly Mediterranean diet appears to be something that's really attainable for most people, and our western palate. So, that's something that if patients come to me asking, you know, “What diet should I follow?” Really the diet for you is the one that you can adhere to and attain without deprivation. But a good place to start, I think, would be the Mediterranean diet. And now you asked about exercise. I think, you know, as a country we've come through lots of iterations of exercise plans, just like we've come through lots of different diet crazes. So, there was a big cardio craze, Jazzercise and step aerobics and different types of exercise. Even Zumba and dance and other exercise programs that were really cardio focused. So cardiovascular exercise, which basically means moving the body to elevate the heart rate into a goal range, because that both helps cardiac health and endurance and also burns calories. So that was thought to be the end all be all for many years. It was thought to be the key to lasting weight loss and heart health. And there's definitely a place for cardiovascular exercise in all of our lives. However, more recent research really supports weight training and resistance training as being the key to a healthy metabolism, weight maintenance, and even bone health, which again is my area of expertise. So, what do I mean by weight training? That can be adapted for many different ages and physical capabilities. So, it does not mean going to the gym and pumping iron for everyone, though that is a great way to get resistance and weight training in. It could mean a chair exercise program using resistance bands or very light ankle and wrist weights. I have a lot of my older patients do a program like that. It could involve Pilates, either Mat Pilates in a studio or reformer machine. Resistance training could include TRX, which is another program that sort of utilizes resistance bands and weights. And it can even include just calisthenics. So, body weight exercises like pushups, pull-ups, sit-ups, planks and various exercises like that. Essentially what resistance training does is it engages our muscles, and over time we can increase muscle mass, muscle strength, and muscle endurance by doing consistent resistance exercise over the course of each week. And not only does that help increase your metabolic rate, it also helps reduce fall risk. It helps with sleep and mood, lots and lots of other health problems which are greatly reduced with weight training. And that would include all cardiac outcomes like heart attack, stroke, heart failure, and then even various cancers are -- the risk is reduced with regular, resistance training. So, it's something that I think everyone should incorporate, at every age, and that's just part of being healthy overall. And the research really does support weight training as the key to a healthy metabolism, maintaining weight loss and bone health.

TODD: How much does metabolism naturally slow down as you age?

DR. TABATABAI: It really is true that at various times in your lifespan you have varying caloric rates, and it has to do with growth. Throughout our life, our caloric needs do change and therefore our metabolic rate will also change. Most of us would agree that, you know, your body definitely changes, and weight loss and weight maintenance become more difficult as you get into your forties and fifties. Women especially feel this way, because the big physiologic change that's coming up around that time, so late forties to early fifties is menopause. So, estrogen is one of the hormones that does regulate metabolism to some extent and also regulates body composition. And so, with the onset of menopause, unless dietary habits are changed, meaning following a healthful diet and probably eating smaller portions as well as changing physical activity, so adding in more resistance training and also cardiovascular exercise, without those changes, most women will experience some amount of weight gain with the onset of menopause. And there's a term called “Menopause Middle,” quote/unquote where women feel like they're gaining more weight around their midsection. And that is actually true. It's been shown that there's more accumulation of fat in the waist area and midsection, and that's actually more detrimental because that visceral fat is linked to heart disease and other things. So, we definitely see that metabolic change in women. We also see changes in men. Now, men actually maintain testosterone throughout their life. The levels are not as high in later years as they are in the adolescent and I would say twenties, and early thirties. There's certainly a change in testosterone over the course of a man's life. And the key though is they don't have the equivalent of menopause in a male individual's life cycle. So, there's no sudden drop and complete elimination of testosterone at any point. And in fact, that would be very detrimental to the health of a male who went through that. So, we do see maintenance of testosterone throughout a man's life. You know, that is the reason, you know, that age old complaint that men can make a few small changes and lose 20 pounds, but women can diet and exercise really strenuously and only lose five. There's some truth to that because men have this maintenance of testosterone and therefore the ability to gain and maintain muscle mass and boost their metabolism through diet and exercise. That difference between men and women is very real. So, that's something to keep in mind. Now, men can absolutely gain weight with age as we often see, and that would really be because they haven't adapted their diet and exercise to you know, their changing bodies. But overall, I would say regardless, if we're looking at females or males, there is a reduction in metabolism as we get older. And our systems slow down and also processes like reproduction aren’t really happening for women, definitely not after the age of 50. Men can continue to father children well into their later years. But even that reproductive process is reduced. So, that change in metabolism sort of mirrors where we are in our lives really physiologically at that point. So, we need fewer calories because essentially our vital processes are becoming sort of pared down and reduced over time.


[Sound effect signaling brief pause in the interview]


ZACH: You may think that middle age weight gain is an inevitable result of your metabolism slowing down, but 2021 research debunked this idea. Researchers pooled data from 40 years of studies involving subjects around the world ranging in age from eight days to 95 years old. They discovered that metabolism does change with age, just not with the ages you might think. Specifically, the study found that metabolism can be viewed as four distinct life stages. Stage one, birth to 1-year-old. The peak is age one, when babies burn calories some 50% faster than adults. Stage two, one to 20, it gradually declines roughly 3% a year during those years. Stage three, 20 to 60. Contrary to perception, metabolism remains stable from early adulthood through middle age and even a little beyond. Stage four, 60 and on. Only then does a steady decline begin, though still less than 1% annually. But by their nineties, people need 26% fewer calories a day than people in midlife. Study authors were just as surprised by the findings as everyone else, not expecting daily calorie needs to decline in adolescence, stay the same during different stages of pregnancy, and remain steady in middle age. In any event, the bottom line is that while several factors might explain expanding waistlines that often emerge during our prime working years, the slowing metabolism isn't one of them.

[Sound effect to indicate resumption of interview]


TODD: So, talk about metabolic syndrome. That's when things kind of break down and go haywire?


DR. TABATABAI: That's a good way of putting it, to be honest. So, metabolic syndrome was really coined as a way to describe the intersection of a lot of negative cardiac risk factors. And these include elevated blood pressure, elevated blood sugar, increased abdominal circumference, and then, also cholesterol. So, either an elevation in LDL or having a low HDL, which is the protective type of cholesterol. So really dyslipidemia is a way to encompass that cholesterol disturbance. So, those factors when they come together is what we call metabolic syndrome. So patients who have metabolic syndrome are at significantly higher risk than an individual who doesn't have metabolic syndrome for heart attacks, stroke, various adverse cardiac outcomes, and ultimately life expectancy is linked to that as well. So, metabolic syndrome is really sort of -- it should be an alarm bell to the patient and also to the physician that risk factor modification is really important, and it has to be a multi-pronged approach for that person. So, not just a diet or exercise program or medication, it likely needs to be a combination of everything that we can do for that person because it is a very high-risk syndrome that needs to be addressed.


TODD: So, I noticed the American Heart Association recently put out a paper defining metabolic syndrome, specifically cardiovascular kidney metabolic syndrome they called it, as a stage condition. It wasn't that before, it was sort of more a description of a cluster of things that auger a bad outcome, but now it's actually seen more as a disease?


DR. TABATABAI: In terms of that syndrome, I think it actually adds to our understanding because the cardiovascular system and the renal system work so closely. And by renal, I mean kidney filtration of the blood. So, I think it really adds to our knowledge and how we're classifying these patients. I think there's definitely some synergy there, meaning the classic metabolic syndrome that sort of focused more on cholesterol, sugar, blood pressure, and then now we have the CKM or cardiovascular kidney metabolic syndrome as well with its own defined stages.  I think it just allows more patients to be recognized as needing help. So, in that way, it's definitely a positive thing. As endocrinologists, a lot of my colleagues treat diabetes, which comes along with heart disease and renal disease. So, there is definitely so much overlap between those systems. So, I think it's important that we sort of partner with our colleagues in the cardiovascular health area as well as nephrology to really come together for our patients. So, I think that's a very positive change.


TODD: So how many people have metabolic syndrome?


DR. TABATABAI: The number keeps rising every year. Some would estimate that up to a quarter to a third of U.S. adults actually have diagnosable metabolic syndrome. And I don't think that's an overstatement. I think that if we strictly apply those components of metabolic syndrome, that it's probably true that about one in three people would meet that criteria. The problem's definitely increasing, and the unifying factor really seems to be an increase in body mass. And so that happens because of an increase in caloric intake, a reduction in activity, and being more sedentary, and most often a combination of those factors. So, as we've seen the obesity epidemic, which really, you know, became a buzzword and a concern over two decades ago, as we've seen that just continue to worsen and spread across the country, metabolic syndrome just follows as a natural consequence of that uptick in obesity.


TODD: I was gonna ask, can you have metabolic syndrome or poor metabolic health and not be heavy, or is sort of heaviness what defines the condition?

DR. TABATABAI: So, that’s an excellent question. I think the vast majority of patients who have metabolic syndrome are at least overweight, if not in the obese category, which is BMI over 30. It’s important to note though that the waist circumference, there’s a reason that that’s in the metabolic syndrome components and not body weight. The reason for that is there are definitely ethnic groups including Asian, Hispanic, and other communities where BMI really doesn’t capture the extent of the metabolic risk. And by that I mean, Asian patients might actually be clinically obese even when their BMI is in the overweight range. And by that I mean, if you have a very, sort of petite body habitus individual and their ideal body weight is around 120 pounds, they could be 130 or 140 pounds and still have just a slightly elevated BMI or even a normal BMI. And that’s problematic because for that individual, looking at them from a genetic standpoint and just a hereditary  standpoint, their cardiovascular system, their metabolic system is not accustomed to having 15 to 20 pounds of excess adipose tissue. And so, if were to include BMI as factor, we would miss that entire chunk of the population. The waist circumference is a really great way to capture those individuals who tend to be overall more lean, but when they carry that extra weight in the midsection, we really see an increase in their cardiovascular risk. So, the South Asian community, which would include, India, Pakistan, Bangladesh, Sri Lanka, that's very, very true. So, these are individuals who are typically not gonna set off alarm bells in terms of their height and weight. They would appear to be lean, but they carry a lot of that excess weight or fat tissue in the waist area, and that visceral fat is problematic. So, having waist circumference I think was a really important way to make sure that we don't exclude groups who are high risk for cardiovascular disease.


TODD: Are there insights we've gained from research into metabolic health that can help people seeking to lose weight?


DR. TABATABAI: think the key is to recognize that there is no magic bullet. I would say that science is allowing us to find ways to assist our patients to do the right thing. And by right thing, I mean eat healthfully and increase physical activity. So, it always comes back to those two sort of cornerstones of healthy weight and weight management and metabolic health. So, I think new medications play a really important role for a large and growing number of patients in whom the classic diet and exercise really hasn't worked. And there's a lot of evidence to suggest that patients who have yo-yo dieted or haven't had success with lasting weight loss, that they would really benefit from having medication assistance in order for them to have sustained weight loss. And that's, I think, a reason that discussion about GLP 1 Agonists and other various medications that might assist with weight loss, that's an important conversation to have between the patient and their physician because not everyone is a good candidate. But I think there is no one size fits all. And what we're learning more and more is that we really need to help ourselves and help our families to eat well and move more.


TODD: Risk factors. I know you've kind of touched on this with women and certain ethnicities. Anything else come to mind?


DR. TABATABAI: So certainly, excess alcohol intake has been a big risk factor for metabolic syndrome and for other adverse health outcomes. So, limiting alcohol is important for a lot of reasons beyond just liver disease, cancer risk, bone health. Alcohol really seems to be linked to metabolic syndrome, and reducing alcohol intake almost always reduces metabolic syndrome as well. So, that's important to do. Smoking, of course, you know. Fortunately, it seems to be much, much less prevalent than it was in decades past, but there's still a significant amount of the population which does smoke cigarettes. And so, we, you know, continue to try to work on smoking cessation, to make sure that we're eliminating a major risk factor for metabolic syndrome and heart disease.


TODD: So, how inextricably linked to lifespan is metabolic health? Is the increasing incident of metabolic syndrome one of the reasons U.S. longevity is --  has stopped increasing in recent years or why it lags behind other industrialized countries?


DR. TABATABAI: I think there's a very strong theory there and there's a lot of evidence to support that line of thinking. And I do think that at a certain point there aren't any medications or any sort of medical interventions that can solve this problem. So, we now have created a society for ourselves that really does not include physical activity as sort of a paramount important factor in everyone's lives. Even just the way that our cities are developed and planned. We don't have town centers and small markets and ways for people to come together and walk to the places that they need to get to. So, you know, we're here in Houston, obviously, each individual and a family has their own car and, you know, we're, we literally have to drive, to even go, a mile down the road, you know, to the store. So unfortunately, I think just because of our society and the way that we're structured, we are really kind of resigned to this outcome unless we make major changes in our own habits and really try to change the way that we structure our day to include a lot of activity and other health behaviors that, you know, can really improve our health.


TODD: So, yeah, I usually try to wrap these up by asking if there’s any takeaway listeners should take from this conversation. That sounds like it’s probably it.

DR. TABATABAI: Pretty much. I think, you know, if any listeners out there, if you have not tried weightlifting or resistance training, there's definitely a way to do it safely at any age. And I have patients who are very concerned that they might hurt themselves or that they might get too bulky. A lot of my female patients worry about that, and I promise that female patients are really not able to bulk up. You know, hormonally we're protected from that. So, that doesn't need to be a concern. But if a physical therapy referral from your physician would help sort of assuage any worries about that, I would definitely encourage that. Especially for older patients, your physician can refer you to see a physical therapist to talk about core strengthening exercises, balance, incorporating weight training into your routine. And then, you know, for younger folks who maybe just wanna start slowly, you can head to a gym, maybe have some sessions with a trainer and then make weight training part of your regular routine for the long term. I think that's something that's very, very key, and the research is really supporting that.

TODD: Alright, very good. I appreciate you taking time to talk with us. It’s been illuminating.

DR. TABATABAI: Absolutely. Thank you so much for the opportunity.


[Sound effect signaling end of interview]


ZACH: So, Todd, are you gonna be thinking about your metabolism now more often.

TODD: Well, as long as I stay lean, I hope not to spend too much time thinking about it. But it did interest me that she puts such an emphasis on strength training or weightlifting.

ZACH: That was counter intuitive right? Because you hear about cardiovascular and you think running and treadmill. But no, she’s like, you know, “Do some resistance bands. Do some weights,” right?

TODD: Yeah. And I really lived through the years where the -- that she mentioned where cardio was such an emphasis. And I hear more now about strength training, but I always still thought it was kind of 50/ 50. But at least for metabolism, it sounds like weight training is much more important. So, I do weight training, so that's not something I have to start anew, but in my current living situation, I'm further from my gym than I used to be. So, I had actually cut back on lifting from four days a week to three.

ZACH: Hmm, first world problems there. Further from your gym...

TODD: Yes.

ZACH: …than you used to be.

TODD: Yes.


True. So, maybe I need to go back to, you know, managing to get there so I do four a week. Although, that’s still...

ZACH:  I mean, four a week, that’s great man.

TODD: Yeah, that’s twice what the recommended -- the guidelines say that you should do weight training -- resistance training or weight training two days a week. So, I’m doing it more than that.

ZACH: What do you find more difficult, like traditional weights or the resistance bands?

TODD: I’ve never done resistance bands.

ZACH: Oh, those are so hard. Those are the worst things. ‘Cause you look at ‘em and you’re like, “Oh, I can do -- I can do 30 of these.” And you’re like -- you get about ten in and you’re like, “Oh, my God.” It depends on the strength of them of course, but I find those equally exhausting.

TODD: Yeah, I’ve never tried them. I’ll need to, I think.

ZACH: Well, on that fourth day, when you get back in rotation, try the resistance bands.

TODD: That’s a good idea.

ZACH: Another thing she mentioned is a recurring theme here on all of our On Health podcasts, apparently, the Mediterranean diet, Todd.

TODD: Yeah, everybody seems to love the Mediterranean diet for any condition it seems.

ZACH: Yeah.


TODD: Whether it’s Alzheim -- you know, warding off Alzheimer’s or if it’s keeping your metabolism in check.

ZACH: Yeah, so, if you’re gonna change your diet, it sounds like that might be the one to do.

TODD: But -- and also, not too much alcohol, Zach.

ZACH: Yes.

TODD: But she was good saying you could have some. It was part of your diet. But don’t have too much. One more buzzkill…


…about alcohol.

ZACH: You know, of all our, “Hey, this might be a health problem, and here’s solutions to it,” I thought this is a fairly positive conversation of like, takeaways, like, “Oh, yeah, I could do all those things.”

TODD: Yeah, she had a -- she was very good about saying you could still live your life.

ZACH: Well, she specifically said like, the best diet for you is the one that you can maintain.

TODD: Right.

ZACH: Right? Because a lot of things you can jump onto and maybe do it for, oh yeah, a week, two weeks, a month, a couple months. But you’re gonna burn out of that eventually if it’s such a radical shift. And so, just finding something that’s manageable for you is always the most recommended one.

TODD: Yes. Yes. I agree completely. I thought it was interesting, her talk about -- she kind of casts some doubt on the value of BMI.

ZACH: Hmm, yeah. BMI, not necessarily a predictor of good metabolism, good health. It’s tricky to -- you know, places that hand out these BMI calculators and like, “Okay, if I’m this height and I weigh this much then I should be good,” right? But not necessarily.

TODD: No, I'm fat by BMI standards. I think if you're in good shape, have some muscle, you often can veer off the BMI standard. Some overweight people's BMI cannot be that bad, and some athletic people's can be too high.


ZACH: Yeah. I mean, there's a lot of counterintuitive stuff about metabolism. Even when they talked about you think, “Oh, well, if I don't eat, then my body will, you know, correct.” And actually eating can kick off your metabolism. I mean it's -- I've heard it recommended like, “Hey, when you get up in the morning, you know, if you feel like you wanna skip breakfast, you should actually just eat an apple or eat something simple to kind of kickstart that metabolism because that can get it going.” 'Cause if you don't, that can actually have the opposite effect sometimes for -- that you're looking for.


TODD: Yeah. I thought that was interesting when she talked about that not eating actually reduces your metabolism, which is not what you -- what people wanna lose weight want to have happen.

ZACH: Exactly. So, definitely worth looking into the medical facts of all this because -- common sense to me says a lot of opposites of what we learned in this conversation, so.

TODD: Yes, yes.

ZACH: Alright, well that's gonna do it for this episode of On Health with Houston Methodist. Please share, like, and subscribe wherever you get your podcasts. We drop episodes on Tuesday mornings. So, until then, stay tuned and stay healthy.

[Music ends signaling end of episode]

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