Tag Archive for: BMI

BRI: It Just Doesn’t Matter

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Continuing our look at the BRI, the mathematician demonstrated that BRI is associated with body fat distribution. It makes sense; the waist measurement would provide an indication of fat around the waist. The next question is: would the BRI be a better predictor for cardiometabolic disorders than BMI?

BRI and Mortality

A group of researchers decided to use open-source data from the National Health and Nutrition Examination Survey database to examine the relationship between BRI and all-cause mortality. They coincided with the years that physical assessments were done including height and waist circumference; body weight was collected but not used in this instance. The time period began in 1999 and continued every two years through 2018.

There were two observations that were significant. First, in every demographic group, regardless of age, gender, or race/ethnicity, the BRI has increased during every examination period. As a country, the U.S. has gotten fatter. That matches every other measure such as body weight or BMI as well.

The second observation was that the hazard ratio (HR) increased as the BRI dropped below normal, then normalized when the normal BRI was reached, and the HR rose again as the BRI increased. Simply stated, there was an increased risk of mortality when people were too lean or too fat.

You may be wondering why I don’t give you a formula to do calculations for yourself. It’s very complicated and there are BRI calculators available on the website below. The main reason is that it just doesn’t matter—the BRI is no better at predicting mortality than the BMI. The researchers had the body weight data they needed to compare the BRI with the BMI directly. They just didn’t do it. However, looking at the mathematicians’ validation study, the categories of adiposity associated with BMI matches up quite well with the BRI and thus with body fatness. There’s no need for any more precision than is achieved with BMI.

The Bottom Line

It’s really the clinical use that seems to bother everyone, but with rare exceptions, the BMI gives an indication of body fatness. If physicians or other health care professionals cannot see the patient before them and realize they are too lean or too muscular to fit the typical interpretation of BMI, the fault lies with them, not the tool they are using.   

What are you prepared to do today?

        Dr. Chet

References:
1. JAMA. 2024; 332(16):1317-1318. 10.1001/jama.2024.20115
2. JAMA Netw Open. 2024; 7(6):e2415051. 10.1001/jamanetworkopen.2024.15051.
3. https://doi.org/10.1002/oby.20408
4. https://bri-calculator.com/#calculator

Body Roundness Index

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The Body Mass Index (BMI) has been used to provide an indication of whether someone is under weight, normal weight, overweight, or obese and the degree to which they are obese. There’s no measure of percentage of body fatness implied, but physicians and other medical professionals have used it for that purpose for a couple of decades. Why? It can be used to assess the potential risk of developing cardiovascular disease, pre-diabetes, and other metabolic conditions.

I happened upon a commentary in JAMA on the Body Roundness Index or BRI for short. It was published in response to a recent study published in a JAMA Network Open by researchers who examined the relationship between BRI and mortality.

Let’s start with this: what is the BRI? The BRI was developed by a mathematician. The reason was interesting; the developer told the commentator that the BMI is based on a “cylindrical” model but when she looked in the mirror, she felt she was more egg shaped. What she did, as a mathematician, was develop a model based on an “ellipse.” Why? She gave a couple of reasons.

The first reason is that BMI can misclassify individuals because it fails to distinguish between individual amounts of fat-free mass (FFM) and fat mass (FM). BMI also does not provide information about the distribution of body fat—specifically, visceral fat versus subcutaneous fat. She developed a mathematical model, to assess body fatness which would indicate where the fat is distributed. With some very complicated math, she developed the BRI. It uses only two measurements: height and waist circumference. The benefit of using the BRI is that it may be a better predictor of body fat than the BMI. Is it? We’ll check out the research study that began this examination of BRI on Saturday, because as Shaq famously said about getting in shape, “Round is a shape.”

The Insider Conference Call is tomorrow night. If you become an Insider by 8 p.m., you can participate in the call to get your questions answered.

What are you prepared to do today?

        Dr. Chet

References:
1. JAMA. 2024; 332(16):1317-1318. 10.1001/jama.2024.20115
2. JAMA Netw Open. 2024; 7(6):e2415051. 10.1001/jamanetworkopen.2024.15051.
3. https://doi.org/10.1002/oby.20408

Your BMI and Shrinkage

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I received several interesting questions regarding the loss of height and its impact on BMI: should you use your current height or your tallest height? I checked the research and found some interesting ideas, but there’s no direct answer.

While it may change slightly over time, your current height should be used to estimate BMI. You’re measuring shorter than you were when you were younger not because you’re stooping (or melting like the Wicked Witch of the West), but because the vertebrae lose bone mass and the disks between them lose fluid and get smaller. You’ve also probably lost muscle mass, but that can be regained; when bones and discs degrade, it’s not reversible as far as we know. That may mean that a person, including yours truly, has a lower target to get to normal weight for his current height.

A new theory of obesity on Saturday.

What are you prepared to do today?

        Dr. Chet

Reference: J Am Geriatr Soc. 2012. https://doi.org/10.1111/j.1532-5415.2011.03832.x

The Bottom Line on the Blue Zones

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The docuseries on Blue Zones demonstrated that it really isn’t complicated to live to 100: find a purpose, a reason to get up every morning, remain physically active, eat reasonably with a focus on plant-based sources for food, and develop a social group that can provide support through the various stages of life.

The docuseries ended with the writer working to create Blue Zones in different cities throughout the USA. That part is complicated because it involves community buy-in from government, health and healthcare officials, as well as professionals from nutrition, exercise, and community planning.

The Most Important Thing

After giving it a lot of thought, I’ve come to the conclusion that the most important thing that anyone can do to live well to 100 is this: get to a normal body weight and stay there. Not everyone who actually was 100 years and older was thin, but they had already made it to 100.

Getting to a normal weight reduces your risk of just about every degenerative disease and reduces the stress on your joints; Paula adds that it also greatly expands your clothing choices. You may never be able to do the splits like the man in the photo, but you’ll be able to do more than you do right now. Genetics is always there to blindside us, but even with that unknown, we can be in a better position by being a normal body weight and maintaining it.

The Blowback Was Instant

I spent last weekend with several thousand people, and I enjoyed every moment. I was asked many times what is the most important thing to be healthy, and my answer was always the same: find a healthier way to eat that you’re willing to stick to for the rest of your life, get to a normal weight, and stay there.

Some replied that “if I got to that weight, I’d look like a skeleton.” Then they would tell me what weight they think they can get to; I gave no quarter, no permission to say that’s good enough. How long that takes you to do could be one, three, maybe ten years. If you’re 43, that means you’ll be 53 and that’s just when everything begins to decline body-wise. You’ll be better able to handle it.

Here’s a simple way to start that you can begin this minute: cut out sugary and ultra-processed foods as much as you can. Then you can go on to find more vegetables you like, learn to cook with less fat, and so on, but you can say no to that donut or cookie right now.

What should you weigh? Here’s a link to the BMI chart at drchet.com. Note that there are guidelines to determine whether you’re big-boned or small-boned, and that affects your goal weight.

The Bottom Line

I would ask nothing of others that I wouldn’t do myself. Getting to a normal weight within a year is my goal; redistribution of that weight may take another couple of years. So what? I don’t know if I have the genes to live to 100, and I don’t know whether that’s my goal. I just want to be able to live like I want every day I’m alive.

No matter your age today, you can help yourself live well longer, and it starts by getting to that normal weight. I know you can do it.

What are you prepared to do today?

        Dr. Chet

Metabolically Healthy and Obese

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The researchers in Germany continued to determine which factors associated with being obese were the most predictive of mortality from any cause and from cardiovascular disease. While not explicitly stated, it seems to me that they attempted to use variables that were simple to assess. With that in mind, here are the variables which demonstrated whether someone was metabolically healthy or not, regardless if they were normal weight, overweight, or obese.

Criteria for Metabolic Health

  • Systolic blood pressure less than 130 and no use of blood pressure lowering medication
  • Waist-hip ratio less than 0.95 for women and less than 1.03 for men
  • No prevalent diabetes

These criteria are simple enough for most people to determine for themselves, no doctors necessary. People usually know whether they’re diabetic, and they also know whether they’re taking medication to lower their blood pressure. Most people have a home BP cuff to assess systolic blood pressure or have access to one in a store.

The waist should be measured at its widest point and hip should be measured at the bony process of the femur. Divide the second number into the first, and that gives you the waist hip ratio.

The Results

The subjects who were considered metabolically healthy and obese had no greater risk of mortality from all causes or from cardiovascular disease then did normal weight, metabolically healthy subjects. This study examined only the death rate, not the rate of disease. Still, I think that if someone is working towards becoming a healthier version of themselves, intermediate goals can be very motivating.

I like this study for two reasons. First, it confirms what I thought for many years: people who are overweight or obese can be metabolically healthy. Second, it means that instead of trying to lose all the weight a person needs to lose, there can be intermediate steps on the way to becoming the best version of yourself; in fact, you don’t even need to be trying to lose weight to start being healthier.

The study also found that some people who were metabolically unhealthy and normal weight or slightly overweight were at higher risk for cardiovascular disease and total mortality. Could it be that the reason for the reduced risk was exercise? It was not considered, but it would be interesting to see further analysis on the data to determine if fitness was a contributing factor in metabolic health.

The Bottom Line

This study provides a basis for assessing risk of mortality on more than just BMI. What it shows is that even though you may be carrying too much weight, that doesn’t mean that you’re automatically at risk for death due to cardiovascular disease or other causes. I believe regular exercise is critical to achieve metabolic health and thus reduce your mortality risk, so that’s your first step to becoming and staying metabolically healthy.

What are you prepared to do today?

        Dr. Chet

Reference: JAMA Net Open. doi:10.1001/jamanetworkopen.2021.8505

Can You Be Obese and Healthy?

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The research question that was most interesting to me as a graduate student was this: could you be overweight, even obese, and still be healthy? That question still interests me today, and for good reason: 70% of the U.S. population is overweight or obese, and we’ve just passed 40% of the entire population falling into the obese category. And it’s not just the U.S.; we’ve exported our poor fitness and diet habits around the world.

Research done decades ago from by Cooper Institute, most often under the direction of Steven Blair, demonstrated that you could be fat and fit. Their research showed that people who were obese, meaning they had a BMI greater than or equal to 30.0, were no more at risk for death from cardiovascular disease or all-cause mortality if they were in the high fitness category.

That’s not the same question as this: could you be metabolically healthy and at no more risk for death from cardiovascular disease or all-cause mortality than someone with a normal BMI (18.5-24.9 kg/m2)? Researchers from Germany decided to examine that question. They used data collected from the National Health and Nutrition Education Survey III, which included over 12,000 subjects, and the U.K. Biobank, which contained over 374,000 subjects. Then they examined the statistical relationship between many different variables such as triglycerides, total cholesterol, hemoglobin A1C, C-reactive protein, systolic blood pressure, and on and on. Once they had a series of statistical relationships between obesity and mortality, then they sought to derive as simple an algorithm as they could to develop a profile of someone who would be metabolically healthy and obese. I’ll tell you more about that in Saturday’s memo.

Meanwhile, have you examined that map that was part of the CDC atrial fibrillation primer? Here’s what I saw: I’ll call it the I-75 Corridor of A-fib. Starting in Flint, MI, if you follow the pattern of the deepest red, it follows I-75 through Detroit to Toledo, OH, then Cincinnati, OH, and all the way down through Georgia to Florida. That’s the I-75 Corridor of A-Fib. What does it mean? Nothing, as far as I know; it doesn’t correspond to race or income or temperature. It’s an observation, nothing more, but maybe some epidemiologist or statistician somewhere will look into in more deeply.

What are you prepared to do today?

        Dr. Chet

Reference: JAMA Net Open. doi:10.1001/jamanetworkopen.2021.8505

COVID-19 and Obesity

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Obesity may be a contributing factor to the severity of symptoms for those who get COVID-19. The best explanation I’ve found why that may be true is in a paper in Nature Reviews Endocrinology published in April. There are several reasons in addition to the cardiovascular and endocrinological co-morbidities associated with obesity.

Just a reminder, by definition obesity is a Body Mass Index (BMI) greater than or equal to 30.0 kg/meters squared; it’s a measure of surface area. You can check yours at the Health Info page on the Dr. Chet website; it also includes the info to determine if you’re really big boned, because that has an impact.

The increased risks associated with obesity are driven by the respiratory system:

  • Impaired respiratory mechanisms
  • Increased airway resistance
  • Impaired gas exchange
  • Low lung volume
  • Low muscle strength

In effect, the greater the obesity, the more difficult it is to breathe deeply and when deep breaths are taken, the resistance within the airway and the actual exchange of oxygen and carbon dioxide are impaired. If required, intubation is more difficult. The greater the degree of obesity, the more difficult it is to provide regular patient care if someone is hospitalized with the virus. Add to all that the co-morbidities of the cardiovascular and endocrinological systems, and it makes recovery very difficult. More research is needed, but it’s a serious issue in a country where over 40% of all adults are obese.

I’ll wrap this up on Saturday with some thoughts about what we don’t know that could be impacting the development of treatments for the COVID-19 virus.

Facebook Messenger

I try to make myself as accessible as possible, and Insiders and Members have quicker access. My website contains a way to email me if you have a question. One way I’m no longer going to accept questions is via Facebook Messenger, so please use one of the other avenues.

What are you prepared to do today?

        Dr. Chet

Reference: Nature Reviews Endocrinology volume 16, pages341–342. (2020)

What’s Your Body Mass Index?

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You may be tempted to measure how you’re doing on the way to your health goals with body composition read-outs on scales and other outputs related to body fat analytics, but how accurate are they? If the device used is one that has you stand on a scale or hang on to handles of some sort, the accuracy of those numbers is very limited.

Those devices are based on impedance technology—the resistance of a very small current passed through your body. It actually can be very accurate when it comes to total body water, something very important for people with congestive heart failure. Everything else is based on algorithms that assume specific characteristics of the body. Those may be valid assumptions, but the variability is too great person to person. How do I know that? I worked on the impedance device as a grad student, so I know it well.

If you really want to track how you’re doing related to fatness, use the Body Mass Index. Every health insurance company uses that as a metric to assess your fatness.

“But I have bigger bones!” you say. Or maybe the weight recommended for you seems too high. In fact you may have a larger or smaller frame than average, and I explain how to know for sure with an easy measurement in the Health Info section titled Body Mass Index. Check it out today for an in-depth look at BMI.

What are you prepared to do today?

        Dr. Chet

Life Expectancy Is More Than Living Longer

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What’s more important to you: living longer or living better with the years you have? Think about it as you read this Memo and I’ll come back to that later.

The Upside of the Study

There were three important lifestyle variables that clearly stood out (1). The more exercise you get, the better off you are. Of those who got perfect 5s, they averaged over an hour per day of exercise. Second, the lower the BMI, the better; researchers didn’t track who might have lost weight over the years to get in the lowest BMI category, but it’s clear that carrying fewer pounds helps.

Finally, the Alternate Healthy Eating Index (AHEI) is a score of the quality of the diet, not the quantity. The highest quintile was below 60 out of 100 possible points. That means you don’t have to eat perfectly; just eat your vegetables and fruit and fewer refined carbohydrates and sugars, and you’ll see benefits.

The Downside of the Study

The subjects were overwhelmingly white and they were nurses and doctors for the most part. Whether that translates to other races and professions, we just don’t know.

The biggest issue for me is the Food Frequency Questionnaire used in the original studies as well as the AHEI scores. Trying to remember what you’ve eaten in so many categories over a year never made sense to me; there’s just too much potential for error. There were also differences in AHEI scores between the Nurses Study (all women) and the Health Professionals Follow-Up Study (all men). The men had an AHEI of 59 while the women in the nurses study had an AHEI of 37.5 in the groups assigned a 5. That makes no sense to me. I know the FFQ were slightly different, but the way the data are extracted to arrive at the AHEI score should have accounted for that. Are men so much better with the quality of their diet? Not buying it.

Supplements

Here’s something I found interesting. The use of a baby aspirin went up as the overall scores went up. In contrast, multivitamin use went up as the overall scores went down. To me, that means that healthcare professionals in all professions know that taking a baby aspirin is good for you. It also means that the poorer the diet, the more people try to compensate with supplements. The goal should be to complement a good diet with a multi, not try to make up for a poor one.

Amount of Time Living with Disease

I asked you a question at the beginning of this memo: what’s more important to you: living longer or living better? Right now, the average number of years spent living with some form of disease is almost 12 years (2). Not every condition is as debilitating as others, but would you rather live longer no matter what your health is or would you rather live well right up to the day you check out? Only you can answer that one. The study didn’t examine quality of life so we don’t know how the subjects did.

Here’s my guess: I would wager that the more healthy lifestyle variables you can add to your life, the longer and better you will live. Eat less. Eat better. Move more. It all starts with those six words.

What are you prepared to do today?

Dr. Chet

 

References:
1. https://doi.org/10.1161/CIRCULATIONAHA.117.032047.
2. https://ourworldindata.org/life-expectancy.

 

The Truth Behind the Obesity Paradox

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In my opinion, the short answer to the obesity paradox is that it doesn’t really exist. But what fun would that be? That doesn’t teach you anything. Let’s take a look at the problems with the research that contributed to this paradox.
 

Study One: Dialysis, BMI, and Mortality

A study of dialysis patients led to the first observation that people with higher BMIs lived longer (1). After tracking over 1,300 subjects on dialysis for a year, researchers found that those who were overweight had a decreased risk of dying and had fewer hospital stays when compared to those who were underweight. This may have been the study that yielded the name The Obesity Paradox. The problem? The study lasted only one year. Trying to generalize what will happen to all overweight and obese people on dialysis from a study that lasted only one year and at only a single location isn’t realistic. It raises an intriguing question, but we’ll need a much more extensive study to really make a solid prediction.
 

Study Two: The Rotterdam Study

I described this study on Thursday (2). While the study appeared to show a protective benefit from being overweight or obese, the subjects were elderly with an average age of 77 at the study’s beginning. One risk factor that you cannot change is age: the older you are, the more likely you are to die. But that’s not the whole story. We can probably say that older people may live longer with a little extra weight, but to extend that prediction to all age groups isn’t valid.
 

Study Three: BMI and Mortality

While this study claimed to analyze the data on over two million people, it was still a meta-analysis (3), which doesn’t yield cause and effect, just a statistical association. Further, they used studies of varying lengths without necessarily knowing exact causes of deaths. They also did not have precise BMIs on everyone; some studies included metrics such as BMI under 27.5 and over 27.5. They tried to include the highest number of subjects, but the quality of data varied and that made it a mess. Researchers chose too many different types of studies in the meta-analysis, and it just doesn’t work. I wouldn’t bet my life on it.
 

Study Four: A Broader Look

The real problem with every approach is the lack of acknowledgement that people with advanced disease may have lost weight before they were included in the study; diseases such as heart failure, diabetes, or renal disease will often lead to weight loss. Those who were heavier when disease hit had the benefit of extra energy stored as fat to deal with the disease, and that could explain the outcomes of those studies. It had nothing to do with being obese; it was a matter of timing.

A study published last month appears to confirm that (4). Researchers in the Cardiovascular Disease Lifetime Risk Pooling Project obtained data from 10 different longitudinal studies, including individual-level data and accurate mortality data. They found that as BMI increased, the death rate from all forms of CVD increased. For those who carried extra weight while younger, CVD occurred earlier, making it more likely they would die before their time.
 

The Bottom Line

As I said, there really is no obesity paradox. Being overweight or obese carries with it risks of degenerative disease. Some people may have better genes and may gain protection for a few years. But in the end, being overweight or obese carries a higher risk of various diseases than the limited protection from an advanced disease you may gain by carrying extra weight. So my advice is the same as it always was: if you’re overweight, your best bet for a long, healthy life is to lose it.

What are you prepared to do today?

Dr. Chet

 

References:
1. Kidney International, Vol. 55 (1999), pp. 1560–1567.
2. European Heart Journal (2001) 22, 1318–1327.
3. JAMA. 2013; 309(1): 71–82.
4. JAMA Cardiol. doi:10.1001/jamacardio.2018.0022.