Tag Archive for: BMI

Essential Tests: Bones and Body Fat

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After Saturday’s Memo, the logical question is: “How do I really know if I’m overfat?” This weeks Memos are going to be about tests. No, you don’t have to study for these tests. I’m talking about medical tests to talk about with your healthcare provider.

At this point, the best way to test for body fatness is using dual-energy X-ray absorptiometry (DEXA). This process uses low-beam radiation and can identify the three main tissues that make up our body: bone mass, lean mass, and fat mass. Yes, DEXA is the same technology that’s used to determine your bone mass to test for osteopenia and osteoporosis. Instead of just doing the wrist and pelvis, the entire body is scanned to determine body composition.

If you want to know your bone health and your body composition, check out the medical services in your area. There’s one hospital that offers DEXA for both purposes in Grand Rapids. If you’re over 40, it’s a great idea to do both tests. The bone scan will most likely be covered by insurance while you may have to pay for the body composition. The cost is about $100 in this area. If you want the most accurate method for bone mass and body composition, check out the DEXA availability in your area.

The goal is to use this information to improve your health. Reducing body fat and increasing bone mass both end up using a similar strategy: Eat less. Eat better. Move more. On Thursday another simple test that’s too often ignored.

What are you prepared to do today?

Dr. Chet-

 

Normal BMI but Still Too Fat

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Last week the health headlines shouted “Study Shows Over 90% of All Americans Are Overfat!” The rate of overweight as assessed by Body Mass Index (BMI) is already 70%; now scientists want to say even more people are too fat? What’s going on? I’ll explain what overfat means first and then tell you about the study behind it.

For the most part, the greater the BMI, the greater the risk for cardiovascular disease, prediabetes, and hypertension. For those of you who aren’t sure of your BMI, check out your BMI in the Health Info section of our website. And if you think you’re just big boned, we show you how to prove it.

But there are people who have a normal BMI under 25.0 but still may be overfat. Considering Waist Circumference in addition to BMI may help but that could still miss some people. How? They may have lost muscle mass; the subtle loss of lean muscle with a gain of fat could lead to overfatness. That increases their risk for the diseases I mentioned earlier.

Here’s the most common example of someone who has a normal BMI but is overfat: a very sedentary elderly person who looks slim, but has very little muscle. As the saying goes “use it or lose it” and they’ve lost it.

A clinician from Arizona has taken it upon himself to redefine the terminology associated with excess body fat. He claims that overfatness gets missed in too many people. The problem he sees is that people who could begin treatment with diet, exercise, and medication if necessary are being missed. He outlined his arguments in a paper published in January 2017 (1), but it was his paper published in July that lead to headlines (2).

He and his co-authors examined the BMIs of people in countries all over the world. Using prior studies that estimated the number of normal-weight people who are overfat, ranging from 9.7% to 20%, he then applied that to the normal-weight populations (as assessed by BMI) in the top 30 developed countries in the world. That’s how they derived the headlines of over 90% overfat—not just in the U.S. but also New Zealand, Iceland, and Greece as well. To be fair, this applied only to males. Don’t rest on your laurels, ladies. All the same countries were greater than 80% for females.

 

The Problems

There are three with his approach in my opinion. First, adding another definition to replace BMI doesn’t really help people or their physicians as he implies. Confirming a person with normal BMI is overfat would require a more advanced exam or assessment of body fat. I’m not sure that’s practical.

Second, I looked at his work from every direction and couldn’t get the numbers to work. If 70% of Americans are overweight or obese and you add 20% of the remaining 30%, it adds up to 76% not 90%. Even if the numbers worked, the statistic would apply to a physician’s total number of patients. There would be no way to identify who is overfat without additional testing.

Third, there’s another group that needs to be addressed, and that would be those who are overweight according to their BMI but are metabolically healthy. In fact, that’s a significant problem today. Even after losing over 30 pounds, my BMI is still in the overweight category. By every test of metabolic fitness—blood pressure, cholesterol, HbA1c, or insulin—I’m at no additional risk of heart disease, yet I’m still classified as “at risk” due to my BMI. I think that’s a greater issue and will be more so as healthcare gets debated. Is your BMI over 25? You’ll pay more, even if your test results are stellar.

 

The Bottom Line

I agree with the concept that the author put forth: there are people with normal BMIs that are overfat, and they’re at greater risk for CVD and metabolic diseases. But new definitions aren’t necessary. What is necessary is identifying who is at risk. That will only occur when doctor and patient meet face to face. When was your last doctor’s appointment?

What are you prepared to do today?

Dr. Chet

 

References:
1. Front. Public Health 4:279. doi: 10.3389/fpubh.2016.00279.
2. Front. Public Health 5:190. doi: 10.3389/fpubh.2017.00190.

 

The Data Must Make Sense

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The data has to make sense before you do any type of statistical analysis; that’s why I always look at the mean and standard deviations. Let me explain what I found that seemed a little off in the Fried Potato Study.

The authors divided the data into quintiles based on potato consumption from less then once per month to greater than three days per week. The researchers reported 19 variables from age to calorie intake to the percentages of various diagnosed diseases in each quintile of potato intake.

I focused on the caloric intake and the Body Mass Index in each category of potato intake. As potato intake increased, the caloric intake increased 600 calories per day—from 1,150 calories per day to 1,750 calories per day. Keep in mind there are 3,600 calories in a pound, so that’s over a pound a week. In every quintile, as the potato intake increased, so did the caloric intake. That could make sense although we don’t know if the additional calories all came from potatoes.

What didn’t make sense was that the BMI for each quintile was about the same: 28.5. That makes no sense at all. If the calories increased, the BMI had to increase for each quintile. It did not. Physical activity could not explain it because those in the highest caloric intake were less active than those with the lowest potato intake. It would be wonderful if calories didn’t add up and we could eat all we want without gaining a pound. I’m sad to say it doesn’t work that way.

While the study leaves that question unanswered and many more, it still isn’t the single biggest question of all. Can you guess what it is—even without reading the study?

What are you prepared to do today?

Dr. Chet

 

Reference: Am J Clin Nutr doi: 10.3945/ajcn.117.154872

 

BMI, WHR, and Lifestyle

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The study we’ve been examining is interesting on so many levels: large numbers of subjects; new statistical techniques due in large part to progress in computing capabilities; genetic analysis that allows for rapid analysis and identification of polymorphisms. It’s all very exciting. You’re probably anticipating a “but” coming and you’d be correct.

This study demonstrated that when using genetic information, WHR is a risk for CVD and type 2 diabetes even with a normal BMI. But there’s still at least two factors to consider that are dependent on each other.

First, just because someone has a mutated gene or genes, it doesn’t mean it will ever express itself, i.e., turn on. More than likely, the second factor has a role to play and that’s the lifestyle of the individual. Some studies refer to it as environment, but they’re intertwined. Where you live may limit or provide you with easy access to healthier foods. It may be easier to exercise in the suburbs than in a large city, or just the opposite given the park systems in different areas of the countries.

Then there’s the home environment: what foods you ate growing up and what your diet is now. All these can impact whether some genes may be expressed. Others may express themselves only when you get to a specific weight or fat intake. The variables are too numerous to consider.

I’m not attempting to confuse the issue. I just want you to know that while this study provides insight that we didn’t have before, you don’t have to be overly concerned. If you keep to a normal BMI and WHR, less than 0.9 for men and less than 0.8 for women, your risk for CVD and type 2 diabetes will not be high.

When all is said and done, it still comes down to three things. Eat less. Eat better. Move more.

What are you prepared to do today?

Dr. Chet

 

Reference: JAMA. 2017;317(6):626-634.

 

Waist-Hip Ratio vs. BMI

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In Tuesday’s message, I said researchers used a unique approach to answering the question of whether waist-hip ratio (WHR) is associated with cardiovascular disease and type 2 diabetes regardless of BMI. They found 48 genes which were associated WHR, a unique approach using the genetic information with Mendelian randomization of epidemiological data. If that isn’t a brain-full, I don’t know what is. Let me see if I can break it down for you.

As I’ve said many times before, epidemiological data cannot show cause and effect; they’re just observations. By using the genetic information related to WHR, researchers can analyze the data by statistically removing the effect of BMI. Because the genetic traits follow some randomization based on Mendel’s genetic work, if the WHR is still associated with the increased risks of disease, that means that where you carry your body fat is important, whether your BMI says you’re overweight or not.

They found that WHR is an independent risk factor for CVD and type 2 diabetes, confirming that the location of your body fat is important regardless of your BMI. That may be why people with a high BMI but low WHR have normal blood pressure and cholesterol levels while others with a normal BMI but a high WHR may have high numbers.

What are you prepared to do today?

Dr. Chet

 

Reference: JAMA. 2017;317(6):626-634.

 

Redefining the Risks of Extra Weight

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Studies show that 70% of the population is overweight; by definition, that means that their body mass index (BMI) is greater than 25 or more. But are all overweight people at the same risk? Just because you’re overweight, are you automatically at greater risk for cardiovascular disease and type 2 diabetes?

That’s what a group of researchers in the U.S. attempted to find out. They had the benefit of access to the U.K. Biobank, an independently funded databank that has collected biometric data on over 500,000 subjects in the U.K. and contains accurate measures of BMI as well as the waist-hip ratio (WHR) on all subjects. They also had one more thing: the genetic information on a large sub-group of subjects. They identified 48 genes that seemed to be associated with WHR and used a unique approach to tease out the effects of WHR from BMI. I’ll cover that the rest of the week.

In the meantime, check out your BMI and measure your waist and hip to calculate your WHR. Measure your waist about an inch below your belly-button and your hips at the widest point; divide waist by hips and you have your ratio.

What are you prepared to do today?

Dr. Chet

 

Reference: JAMA. 2017;317(6):626-634.

 

Obesity: A Global Problem

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The overwhelming conclusion by the Global BMI Mortality Collaboration is that the rate of mortality linked with the degree of obesity follows the same pattern in the entire world with one exception: South Asia. If you look at the graphs of the mortality rate per BMI category, they’re virtually identical in North America, Europe, Australia, New Zealand, and East Asia. One of the reasons that South Asia might be different was that only three studies were included in the analysis.

We are not alone in our fight to lose weight and get healthier. Actually, that’s a completely different . . .

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Death by Obesity

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The Global BMI Mortality Collaboration examined the mortality of being overweight and obese in most parts of the world. They purposefully did not include people in the meta-analysis who had ever smoked or had a chronic disease when the study began; that makes sense because both can affect mortality within the five-year span they were examining. The range of the subjects was 20 to 89 years old and a BMI greater than 15.0.

They performed a hazard ratio analysis of the combined data, which examines the rate of an event (in this case death) within each weight . . .

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The World’s State of Obesity

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A week ago, I talked to a reader and visitor to my website who continues to check her BMI occasionally to see where she stands; she still hasn’t made it to the normal range but continues to try. I understand—I’m not there yet either. But there’s good reason to keep trying based on a recently published study.

The Global BMI Mortality Collaboration decided to examine the deaths from overweight and obesity in the entire world. Sometimes we think that the U.S. is the only overweight nation in the . . .

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Health Habits: Just Do Better

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Let’s finish up our look at the recent paper that concluded we’re doing poorly when it comes to our health habits (1). If you thought smoking and exercise were underwhelming, today we’ll look at diet and body fat.

When it comes to following the U.S. Department of Agriculture Dietary Guidelines, just under 38% hit that goal. I’ve talked about this a lot over the years, and this isn’t a debate over what constitutes a good diet. While we are doing somewhat better, adults do not eat enough vegetables, fruits, or beans, and we still . . .

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