Muscle for Life with Mike Matthews - The Truth About BMI Charts . . . (Isn’t What You Think)

Episode Date: June 19, 2020

“One of the most popular ways of telling if you're a healthy weight is bogus “BMI Is A Terrible Measure Of Health” “5 BMI Myths You Need To Stop Believing” These are the titles of several articles on BMI and BMI charts published in recent years. If you take their message at face value, then you’ll come to one conclusion: BMI is outdated, overrated, and inaccurate, and it’s time we retired it for good. In case you didn’t know, BMI stands for “body mass index,” and it measures the relationship between your height and weight. BMI has been used by doctors for decades to help determine whether someone should consider losing or gaining weight, but recently this idea has come under fire. Detractors say you can’t distill what it means to be healthy into a single number. Some go further and say being overweight isn’t unhealthy, so why bother measuring BMI or worrying about your weight? Others point out that BMI charts don’t work well for muscular people. Who’s right? The short story is twofold: 1) BMI charts are good at estimating the body fat percentage of large populations of people, and they do this quite well. 2) Although imperfect at estimating the body fat percentage of individuals, BMI charts are still decent barometers of whether or not you should lose weight. The long story? BMI charts are one of the best ways to get a quick bird’s-eye view of your body composition and overall health, but you should also rely on several other methods to get a more accurate estimate of your body fat percentage. Let’s start by looking at what BMI is. --- Timestamps: 2:08 - What is BMI?  3:26 - What are the problems with BMI measurements? 7:04 - What does BMI measure well?  9:34 - What is a healthy weight and body composition?  --- Mentioned on the show:  How to Calculate Your Body Fat Percentage: https://legionathletics.com/how-to-calculate-body-fat/ Legion VIP One-on-One Coaching: https://legionathletics.com/coaching/ --- Want to get my best advice on how to gain muscle and strength and lose fat faster? Sign up for my free newsletter! Click here: https://www.legionathletics.com/signup/

Oh, hi there. I'm Mike and this is my podcast Muscle for Life. Welcome to another episode. Thank you for being here. This episode is going to be about BMI, which is a beginner topic, but I wanted to put out an episode specifically on it because I still get questions mostly from beginners, but sometimes even from more experienced fitness folk about BMI versus body composition and body fat percentage and how they differ and which one you should be paying attention to and why. And BMI often gives people trouble because that's something that doctors have looked at and used for a long time. And in case you are not familiar with it, it stands for body mass index. And it is an indicator of how overweight you are because it is a relationship between your height and your weight. And there is a very simple chart,

again, that often doctors use to determine if someone should gain weight or lose weight. And the problem with BMI, and this is something I'm going to get into in this podcast, is it works pretty well at a population level. And it works fairly well with people who are sedentary and particularly people who are overweight and sedentary, but it is not very useful as a diagnostic tool with people who are into working out because it doesn't do a good job estimating body fat percentage and therefore giving you a view of body composition. And that's really what matters a lot more than body weight, right? Is what that weight is made up of. That said, BMI charts are still a decent barometer of whether someone should gain or lose weight if they're not far more muscular than the average person. And so that's a quick little summary of what we're going to be discussing on today's episode. All right. Now I mentioned this in the little intro blurb, but I'm just going to be discussing on today's episode. All right. Now I mentioned

this in the little intro blurb, but I'm just going to say it again in case you skipped that. BMI, what is it? Well, it stands for body mass index, and it is a measure of your body weight per unit of height. And how it's calculated is you divide your body weight in kilograms by your height in meters squared, gives you your BMI. And it's usually expressed in the context or shown in the context of a chart, right? And the chart usually divides people into four categories based on their BMI. You have underweight, which is a BMI of less than 18 and a half, 18.5. You have normal weight, which is a BMI of less than 18.5, 18.5. You have normal weight, which is a BMI of 18.5 to 24.9. You have overweight, which is a BMI of 25 to 29.9. And then you have obese, which is a BMI of 30 or greater. And that all sounds nice and useful, very neat, very practical. And it is at a population level. When you're looking at a lot of people, then if you

were to take their BMIs individually and then average it, that would give you a good idea of whether a population is generally underweight, normal weight, or overweight. It also can be useful with someone who is sedentary, who doesn't work out, and particularly someone who doesn't train their muscles, who has a normal amount of muscle mass or even less than a normal amount of muscle mass. However, there is a major problem with the BMI measurement and those categories. I, for example, according to my BMI score, am slightly overweight. I'm right at the top. I'm around 25. I'm right at the top of normal weight at the bottom of overweight. And some doctors, if they weren't looking at me, if they just saw that, they would say that I might want to lose a little bit of weight for my health. And that would be kind of ironic, of course,

because I'm 6'2", I'm 190, 191 pounds, and I'm about 9% body fat right now. So of course, I don't need to lose weight to get healthy. In fact, if I were to try to lose much more body fat, I'd actually start getting down into a range that would be unhealthy to maintain at least. It is not healthy to maintain, let's say, 6% or 7% body fat. At least for most guys, that is going to entail negative side effects that are associated with just low body fat levels and stuff that you can't get around because of the lowered amount of leptin, which is a hormone that's produced by body fat that tells your body that it has plenty of energy, that energy is abundant and that it can expend energy freely and it can run its metabolism at maximum speed. And if you want to learn more about that, head over to legionathletics.com and search for healthy

body fat percentage. And you'll find an article that I wrote on this topic. What are healthy body fat percentages for men and women? I may have done a podcast on this as well. I would think that I have, but I can't say for sure. And so getting back to BMI and the problem here and why, according to BMI, I am slightly overweight is it's not taking into account body composition. It's not taking into account how much of my weight is muscle versus body fat. And that's why, according to BMI, I am overweight, right? Because it only takes into account weight and height, not body fat percentage or body composition. It just looks at my weight and it looks at my height and basically says, well, in an average dude who's not into weightlifting, this would be overweight. He would have to be carrying around

a lot of fat to have a BMI of 25, or at least an above average amount of fat to have a BMI of 25. And yes, that would be correct if I weren't into training my muscles, but I am. That's why I have a podcast called Muscle for Life. BMI though can also incorrectly categorize people as normal or overweight when they're actually obese. For example, a 2010 meta-analysis conducted by scientists at the Mayo Clinic looked at the BMIs of 32,000 people whose body fat percentage was measured. And what they found is half of the people who are considered normal weight or overweight, according to the BMI measurement, were actually obese based on their actual body fat percentage, which would be 25% or higher in men would be considered obese. That's the low end of obesity and 35% body fat and higher for women. That's where obesity begins for women. And the reason for

this finding is many of these people were skinny fat. Many of them were under-muscled. They had quite a bit less muscle than average and quite a bit more fat than average. Of course, bringing their body fat percentage high enough to qualify them to be called obese, but not their body weight according to BMI. Now, where BMI works well on an individual level is estimating obesity. And that's because when you gain enough body fat, BMI does actually predict your body fat percentage pretty well, and in most people, well enough to classify them accurately as obese, regardless of how much or how little they're carrying. Because of course, pretty much all people who are obese, there are the outliers. Maybe there are some powerlifters out there who would be technically obese because

of their body fat level, but are powerlifters and are super jacked. The vast, vast majority of obese people are not super jacked. They're just very overweight. And in case you're wondering if you could gain enough muscle and be fairly lean to register as obese in the BMI scale, no, not naturally. You'd have to be on drugs. You'd have to be on a lot of drugs to gain that much muscle. Now, another common claim is that big boned people or people with very dense bones can end up in higher BMI categories than they should be. And while it's true that some people do have heavier bones than others, the differences are too small to have any significant impact on BMI because your skeleton really contributes only about 15% of your total body weight. Another criticism often leveled at

BMI is that the categories aren't useful for women because they carry around more essential fat than men. And while that's true, it's not a big enough difference to invalidate BMI. And neither is the fact that it was created a long time ago. It actually was created back in the 1800s. That doesn't mean that it's not useful because human proportions and basic mathematics have not changed in the last couple of hundred years. Many people like to attack BMI just because it's a number they don't like, right? If their BMI says they are obese, they are almost certainly obese, or maybe they use a lot of steroids, and they don't like that. And unless you lift weights and unless you are more muscular than the average person,

if BMI says that you are overweight, you are probably overweight and it would probably serve you well to lose some weight. And if BMI says you're underweight, it probably would serve you well to gain some weight. And ideally in the way of muscle gain, not just put on fat, that is not going to be as beneficial as getting into weightlifting and getting to a normal weight that way. Now, all that said, there is a better way to know if you are at a healthy weight and more importantly, a healthy body composition, right? Because that really is the key. Remember the study that I referenced earlier where it was looking at people

who were obese and that starts at 25% body fat in men and 35% body fat in women. And once you get into that range and higher, once you get up to that level of body fatness, your risk of disease and dysfunction rises markedly. And so really what we want to do is we want to have a healthy body composition. And for that, we can track body fat percentage, for example, which you can get very meticulous with, but it's not really necessary. Honestly, for our purposes here, you can just go by the mirror. And so if you head over to legionathletics.com and you search for body fat percentage, you'll find a long article I wrote that also has a calculator to help you figure out your body fat percentage more accurately if you want to take

some caliber measurements. But if you don't, there are some pictures in the article that show you what certain levels of body fat look like in both men and women. And the men and women in the pictures are fit. There are people who are into working out because most of the people reading the article are also into working out. So it wouldn't be exactly relevant to show 15% body fat in a guy with no muscle if most of the guys who are going to be reading the article and looking at the image are going to have some muscle. And that's going to be the case, though, I'm assuming with most of you lovely people listening to me right now, most of you are into working out and you might not be jacked, but you're more fit than the average person. And so the images will probably work more or less. That's it. That's all you'll really need is compare the

image to where you're at. And you'll be like, oh, cool. I'm in the range of this to this. And as far as a healthy body fat level in men, let's say that the sweet spot is probably between 10 and 15%. You could be a bit higher and be healthy. You could be 16, 17, maybe even upper of 20%, but a sweet spot is 10 to 15%. 10 being the low end of it. Well, obviously the low end, but it's the more difficult to maintain end of that spectrum. It is not very hard for most guys to hang out around 15%, but to maintain a legitimate 10% requires really what it comes down to is you have to be pretty OCD about your calories, about your energy balance. It is, and I'm speaking from personal experience here because I've maintained that level of body fat

for long periods of time. What helps a lot is doing a fair amount of cardio, a couple of hours of cardio per week to get that energy expenditure up and following a meal plan pretty consistently, really. And it doesn't mean you have to be weighing and measuring everything you eat, every meal, but you really do have to know where your calories are at. Let's say within the range of about 10%, that's your margin for error. And I should also mention that you also can't do too much in the way of quote unquote cheating. You can't have too many blowout meals or days where you're just eating one, two, 3,000 calories above maintenance. You have to keep your calories in a steady range seven days a week, and you have to keep your

energy expenditure up. That's what it comes down to if you want to stay lean for long periods of time. And in women, we're talking about a healthy body fat percentage of 20 to 25% is a sweet spot. Again, women can be healthy at slightly higher levels, but once you get into the 30 plus range, you're now entering the unhealthy range of body fatness. And in women, 20% is a very athletic look. Most women I've worked with over the years, that's really what they're looking for in terms of a physique. They want to gain probably 15-ish pounds of muscle in the right places on their body, and they want to be around 20% body fat. And that's where they look lean and toned and defined, but they still look like women.

They have curves, and they don't have too much vascularity around their body, and they look like athletes. And that's really the key point I want you to take away from this episode is focus on improving your body composition, maintaining a healthy and aesthetic body composition, and don't worry about where that lands your BMI. If you maintain your body composition, if you get it to where you want it to be and assume that's a healthy place and then stay there, you don't have to care what your BMI is. And if you want to learn more about that,

about improving your body composition, and if you're not sure how to go from where you're at to where you want to be, there are a couple of articles over at legionathletics.com that I would recommend. One would be my article on recomposition. So if you just search for recomposition, which is a fancy term for gaining muscle and losing fat at the same time. That will probably be helpful for you. And you may want to check out my article on skinny fat if you feel you are skinny fat, and you can just search for skinny fat over at the website and you'll find that as well. All right. Well, that's it for today's episode. I hope you found it interesting and helpful. And if you did, and you don't mind

doing me a favor, could you please leave a quick review for the podcast on iTunes or wherever you are listening from? Because those reviews not only convince people that they should check out the show, they also increase the search visibility and help more people find their way to me and to the podcast and learn how to build their best body ever as well. And of course, if you want to be notified when the next episode goes live, then simply subscribe to the podcast and whatever app you're using to listen and you will not miss out on any of the new stuff that I have coming. to listen and you will not miss out on any of the new stuff that I have coming. And last, if you didn't like something about the show, then definitely shoot me an email at mike at muscle for life.com and share your thoughts. Let me know how you think I could do this better. I read every email myself and I'm always looking for constructive feedback. All right. thanks again for listening to this episode and I hope to hear from you soon.