
Body roundness index: A new way to calculate body fat
Transcript
Host Amber Smith: Upstate Medical University in Syracuse, New York, invites you to be The Informed Patient, with the podcast that features experts from Central New York's only academic medical center. I'm your host, Amber Smith.
The body mass index has been criticized as too general and inaccurate. Now, doctors are considering the body roundness index. Here to explain is exercise physiologist Carol Sames. She's also an associate professor of physical therapy education at Upstate.
Welcome back to "The Informed Patient," Dr. Sames.
Carol Sames, PhD: Thanks so much, Amber. Glad to be here.
Host Amber Smith: Now, before we get into the body roundness index, what is the body mass index, or BMI, that people may have heard of?
Carol Sames, PhD: Well, it's just an index that was created back in the 1830s by a Belgian mathematician. And he created it because he wanted to try to calculate the average Caucasian man.
Host Amber Smith: OK, so it really doesn't apply to everyone.
Carol Sames, PhD: No, it doesn't.
Host Amber Smith: So the purpose was just to be able to gauge people's weight, or what?
Carol Sames, PhD: Well, to figure out what was average, and then from that, clearly, to identify what was not average in terms of height and weight. it really didn't have any significance.
But in the 1970s, a physiologist termed the body mass index as that term, because before then it wasn't known as a body mass index. And then this physiologist said, "Hey, I wonder if we could use it in looking at population health?" And so he started to do some research and of course it was done on Caucasian males, and it really didn't become popular until some of the research demonstrated that there could be an association with some negative health.
Host Amber Smith: The body mass index, as it is now, can it be used for women or non-Caucasian people, or does it work for tall people and short people the same?
Carol Sames, PhD: Well, that's the problem, because it was originally developed and tested on Caucasian males, so it wasn't ever designed for health screening. It doesn't take into account any racial, ethnic, age, sex, gender diversity differences, so that's a big problem.
And then the other big problem is that weight in and of itself, doesn't necessarily tell us about the composition of that weight. Really, the negative health outcomes are associated with fat, sometimes called adipose tissue, not muscle mass, so if we can't differentiate in somebody, you could have somebody who is very muscular and ends up with a higher BMI because they weigh more on the scale, but they're very muscular, so if you actually looked at their percentage of body fat, it's low. But they could get categorized as having a high BMI, which then might set off triggers, like say I am trying to apply for health insurance or life insurance. I mean, it's got some negative consequences there. They're two major inherent issues with BMI.
Host Amber Smith: So does a high BMI correlate with other health metrics -- blood pressure or blood work or anything?
Carol Sames, PhD: The answer is possibly yes and maybe no. So if we just take BMI as a number, and we don't look at the individual person, there could be a lot of error there.
Again, we could have somebody who's incredibly muscular, right? Or we could have somebody who maybe has body fat that they store more in their hips and thighs and buttock area, and that distribution of fat mass generally doesn't have all of the adverse consequences as fat mass that's more in the stomach area. It's called visceral fat, and that does have some negative health consequences.
So BMI is not differentiating where that fat is stored. So I say yes and no because if we know the person, and we can observe the person, and we could see their BMI, and maybe look at their waist and their hip measurements, we could see how their fat is distributed. If we looked at maybe some blood work, then maybe yes, we could say it is correlated. But just on an individual, person by person, there's a lot of variability involved there.
Host Amber Smith: Well, what can you tell us about the new metric, the BRI, the body roundness index?
Carol Sames, PhD: The BRI is quite interesting and, again, also created by a mathematician. And this one came out in 2013, and what it involves is height and waist measurement, so it's not looking at weight; it's looking at waist measurement. There are some calculators that will also put in a hip measurement, too, but her original one was just height and waist. And the reason that people are liking this BRI is that you can look at maybe how fat is distributed because you're getting this waist measurement.
So as waists get larger, that's telling me that I have more storage of fat in my stomach, abdominal area, and again, that fat, that type of what we call central body fat has been demonstrated to be associated with some negative health outcomes, so the development of Type 2 diabetes, hypertension, metabolic syndrome, stroke, cardiovascular disease, poor lipid profile or our cholesterol profile, than fat that's stored in my buttocks and my thighs and my hips. So there is a difference in that fat.
Host Amber Smith: So with the BRI, the weight doesn't matter, then. They don't even calculate weight.
Carol Sames, PhD: Correct. They're not even using weight at all.
Host Amber Smith: So are medical offices using this yet?
Carol Sames, PhD: Well, it's interesting because in June of 2023, the American Medical Association suggested that BMI has many limitations, especially, again, at the individual level, and that other measurements of health risk could be better potentially or used in conjunction with BMI, such as waist circumference, this BRI, or actually looking at body composition or measuring that abdominal fat. So they're saying there's some issues with BMI, but to say that I've gone to my doctor, and they've done a BRI, that has not happened.
And I think the medical community tends to be a little slow to change, and there's so much research on BMI, and there's not as much on BRI, because it's newer.
Host Amber Smith: This is Upstate's "The Informed Patient" podcast. I'm your host, Amber Smith.
I'm talking with exercise physiologist Dr. Carol Sames, who's an associate professor of physical therapy education at Upstate.
How can people calculate their own BRI?
Carol Sames, PhD: If you Google and go to "BRI calculator," you can get a calculator that just plugs those numbers in. It's a pretty complicated math equation. So you just can plug in your height and waist, and it will spit out a number for you.
Host Amber Smith: So you need to have a measuring tape to measure your waist?
Carol Sames, PhD: Yes.
Host Amber Smith: You need to get an accurate height.
Carol Sames, PhD: Yes. Correct.
Host Amber Smith: When we talk about measuring the waist, so people don't get confused and measure their hips instead, is there an easy way to explain how to get a proper waist measurement?
Carol Sames, PhD: A waist (measurement) should be above the pelvis, like your hip bones. So you actually want to be above that, like up, and that's where you want to measure your natural waist. Usually that involves your belly button. For most people, it should involve the belly button. It should come across there.
Because for hips, you actually want to go across the biggest part, so we're really talking around the biggest part of your butt and around. So usually, for most people, that's almost down like where your pubis is, when you come around from the butt. That's going to be a little bit lower. But waist should be above your hip bones.
Host Amber Smith: So what is a healthy score?
Carol Sames, PhD: Because there's not a whole lot of research done with BRI, the estimate of what they would consider a good score is somewhere between 3.5 to 5.5. But again, because this is a newer index, the data is not there on a huge population level yet, so at least that's the estimate we have now, about 3.5 to 5.5.
Host Amber Smith: So do we know yet what a high score means if you're above 5.5 or if you're below 3.5?
Carol Sames, PhD: What the research has at least indicated so far is that if you have a score above 7, that is associated with higher early mortality, also mortality from certain cancers, heart disease. They're what has been demonstrated so far.
And then, a lower score is considered below 3. So a lot of times people think, "Well, a lower score would be better." And that's not true, and that's also not true with BMI. When you get low BMI scores, that can be very concerning, again, because you see a higher mortality with those lower scores, and a lot of the individuals that have those lower scores tend to be adults that are 65 and older, and that can occur because of malnutrition, just losing muscle mass or inactivity. And with older adults, we know that sarcopenia is a process that results in us losing muscle mass, and that means we get weaker. And then that means we have less power, so getting out of a chair, going upstairs, those activities require power.
And this occurs as we get older, even if I'm very physically active. Now, the amount of loss is less, but it occurs. It's a physiological process. And so, as you start to lose muscle mass, then that is going to clearly impact my ability to function, whether it just be doing things around the house, like activities of daily living. It also increases my risk of fear of falls and then falls. And they're certainly things we want to avoid as we get older. So, having a low BMI and a low BRI is not necessarily healthy and probably, again, at the individual level needs to be investigated.
Host Amber Smith: So for someone whose BRI is not around 5-ish or 5 or 6, say they want to reduce it to that or increase it to that, what is the best strategy for that?
Carol Sames, PhD: So the first thing I would say is you always want to go to your doctor, right? You really do need to know, "Where are my blood values here? Are my lipids starting to increase? What is my fasting blood sugar?" Those kinds of things.
But after that, if a person has not been active. Activity is just such a wonderful thing. And not just activity, but something that involves strength training, and it doesn't have to involve weights. You've got a body, and that body can move, and you can increase strength just by using your body and a wall or a chair.
And then something that is continuous. So something like walking, something that is just a continuous activity. Because what that's going to do is, it's going to increase your muscle mass, which certainly then is a good thing, and it can help to reduce fat mass.
One of the things we don't realize is that as we get older, fat actually starts to go into our muscle. It infiltrates the muscle, and so the muscle clearly is not as strong. And when we start to have fat in muscle, that also causes a cascade of other issues. So being active, and again, any activity, for any amount of time, is always better than nothing.
And then, I always think it's good to investigate, "What is my nutritional status?" In many cases, people can keep a diary, but there are times when maybe I'd want to have a discussion with my physician about, "Should I go see a registered dietitian, somebody that can help me?" Maybe as I look at my nutrition, I don't have enough protein, and I'm going to need protein to increase muscle. Or maybe I'm not drinking enough water, right? All those things that can occur. Or maybe I have a lot of really fast, broken-down carbohydrates; I'm eating more processed types of foods.
Sleep: How am I sleeping? When we don't have consistent, good sleep, we get an increase in inflammation. And the problem with inflammation is it affects all body systems. So, am I sleeping regularly? Am I getting enough sleep for myself? And, again, that's where a visit to the physician could be helpful.
What about chronic stress? All of us are dealing with different stressors. Is it something that is impacting my health? Because that can also cause me to deposit more of that bad abdominal fat. Chronic stress, lack of sleep, even in the presence of me being active, so there's a lot of different things. It's not just one choice I make, it's really more a number of choices that I choose to make.
Host Amber Smith: Since we're talking about the abdominal fat, I thought you were going to say, abdominal exercises -- sit-ups and planks and other things like that. Will those help? Will those help a person slim down so that their number is better?
Carol Sames, PhD: So again, it's always going to depend on how much energy I'm taking in, right? But you can't spot-reduce. I wish we could. I wish that we could do lots of sit-ups and planks, and miraculously, my waist gets smaller.
But generally speaking, in terms of losing fat, we lose it in the reverse of where we gained it. So if you gained more of your weight in your stomach area first, that's going to be the last place that it generally will come off.
It would be great if spot reduction worked, but it doesn't.
What sometimes people do is, if they do start to do a lot of core exercises, they may notice that they feel taut, or stronger, and that's the muscle there, but that doesn't necessarily mean that I've lost the fat mass that is there, but it's still good. Core exercises are really important. You need to have a strong core in order to have strong arms and legs.
Host Amber Smith: Now, these new weight-loss medications, Ozempic and Wegovy and the others, if you're on those and you're naturally losing weight on those, are you going to lose it in your abdomen?
Is it going to help you get a better BRI number?
Carol Sames, PhD: Well, they have been quite effective for most people, again, if we talk about population here. But there are some concerns because people can have issues, stomach issues. The other concern is that when people stop taking the medication, people have noticed a rebound in terms of weight gain. That's why I think it's really important that, if I am going to take one of these medications, that I'm also exercising, right? Because now I'm trying to establish a routine of regular physical activity so that I don't have that rebound effect.
We need muscle to move, so at the end of the day, I could lose a lot of weight but be incredibly weak, and that doesn't bode well for anyone. So, muscle is power, right? We need to have muscle, everyone, regardless of age.
Host Amber Smith: Well, Dr. Sames, thank you so much for taking time to tell us about the body roundness index.
Carol Sames, PhD: My pleasure.
Host Amber Smith: My guest has been Carol Sames. She's an exercise physiologist and associate professor of physical therapy education at Upstate.
"The Informed Patient" is a podcast covering health, science and medicine, brought to you by Upstate Medical University in Syracuse, New York, and produced by Jim Howe, with sound engineering by Bill Broeckel and graphic design by Dan Cameron.
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