Body Weight, Bmi, Waist Size – Which is the Best Indicator of Health?

Body Weight, Bmi, Waist Size – Which is the Best Indicator of Health?

Body Weight, Bmi, Waist Size – Which is the Best Indicator of Health?

Do you step on the scale every day or every few days to track your weight?  If you see your weight falls into the “normal” range for your height, you might do a little happy dance and assume you’re healthy. In reality, body weight as measured by a standard bathroom scale, says little about your health.

We now know that a significant portion of the population, mostly people who don’t resistance train, suffer from “normal weight obesity.” As the name implies, normal weight obesity means your weight is where it should be for your height but your body fat percent is too high.

What’s disturbing about normal weight obesity is people who fall into this category have the same metabolic risk factors as those who are obese. In other words, the scale offers a false sense of security for people with normal weight obesity.

According to the Mayo Clinic, normal weight obesity increases the risk of many health problems obese people suffer from, including type 2 diabetes, high blood pressure, metabolic syndrome, and heart disease. So, a standard scale is actually a very poor measure of metabolic health.

So the scale’s not a reliable indicator of health. If that’s the case, is there a better measure you can use that doesn’t involve blood tests etc.?

Body Mass Index: A Metric That Still Falls Short

Body mass index, or BMI, is a measure health care professionals use to determine whether you need to lose a few pounds, gain a few pounds, or stay the same. What this measurement does is compare your body weight to your height, using a specific formula. This formula divides your weight in kilograms by the square of your height in meters. You can find body weight calculators that do the calculation for you online. A so-called “healthy” BMI falls in the 19 to 25 range.

Unfortunately, BMI has its limitations, particularly for athletic people and those who lift weights. Since BMI looks at your total body weight relative to height, it doesn’t take into account how much body fat versus muscle you carry on your frame. It also doesn’t consider how much bone mass you have. If you have larger bones, your BMI will be higher than someone who has small bones with the same height and amount of muscle and body fat.

If you weight train and have a significant amount of lean body mass, your BMI may fall into the overweight or obese range, despite the fact you’re in exceptional physical shape. In fact, some athletes are in the obese category by BMI measurement. Measuring BMI is least accurate as a health evaluation tool for people who exercise and for the elderly.

Another limitation of BMI is it doesn’t tell you anything about where fat lies on your body. Research shows carrying more body fat in certain areas, around your tummy and waistline, is riskier from a health standpoint than being hip or thigh heavy. BMI tells you nothing about body fat percentage OR fat distribution.

What if you have a normal BMI and a “muffin top” waistline? The reality: you’re at higher risk for metabolic problems, but it’s not apparent from your BMI.

Waist Circumference

No doubt you should follow your body weight, as limiting as it is, but a better indicator of your metabolic health is your waist size. That’s because waist size is a good indicator of how much visceral body fat you have. Visceral body fat is fat that lies deep in your abdominal cavity, unlike the superficial fat you can pinch between your fingers.

What’s so bad about visceral fat? It’s linked with a greater risk for heart disease and type 2 diabetes, even when you control for weight or body mass index. The arbitrary cut-off for an unhealthy weight size for females is 35 inches, but you really shouldn’t have a waist size larger than half your height. If you’re 5 feet tall, or 60 inches, your waist circumference should be no greater than 30 inches.

A number of studies show even in women with normal BMI and body weight, having a large waist circumference is a strong risk factor for heart disease. Plus, a study published in the Archives of Internal Medicine showed a link between an increased waist size and dying from all causes.

BMI AND Waist Circumference Are Better Than Only One

BMI is a quick measure your doctor might use to determine if you’re overweight or obese but it doesn’t necessarily tell the full story. Better to monitor a combination of BMI AND waist circumference over time. If your doctor doesn’t do it, you can check your own waist circumference at home.

To measure your waist circumference, wrap a tape measure around your waist at the level of your belly button. Don’t pull too hard on the tape measure but make sure there’s no slack. Also, don’t suck in your gut or hold your breath to make the measurement smaller. That’s cheating!

Once you have the measurement, recheck it every 6 months and make sure it isn’t changing. If you’d like a rough idea of your body fat percentage, you can use calipers to measure skinfold thickness. More accurate ways, which aren’t practical for home use, include underwater weighing, bioelectrical impedance, and dual energy x-ray absorption.

What about body fat scales? These scales use bioelectrical impedance to determine your body fat, although they’re not entirely accurate. Factors like your level of hydration, the temperature in the room, and even doing a workout prior to measurement can alter the results. They can be useful for tracking changes in your body fat if you step on a body fat scale at the same time each day, first thing in the morning is best.

 

References:

Mayo Clinic. “Obesity”

Ned Tijdschr Geneeskd. 2004 Nov 27;148(48):2379-82.

Int J Prev Med. 2015 Jan 15;6:5. doi: 10.4103/2008-7802.151434. eCollection 2015.

Harvard T.H. Chan School of Public Health. “Waist Size Matters”

Arch Intern Med. 2007;167:886-92.

Am J Clin Nutr March 2004 vol. 79 no. 3 379-384.

Br J Nutr. 2014 Nov 28;112(10):1735-44. doi: 10.1017/S0007114514002657. Epub 2014 Oct 10.

Today’s Dietitian. Vol. 16 No. 1 P. 30. January 2014.

Nutr J. 2008; 7: 26.

 

Related Articles By Cathe:

3 Tests that Outperform BMI for Monitoring Obesity & Health Risks

3 Reasons the Scale Says You’re Heavier that Have Nothing to Do with Body Fat

Normal Weight Obesity: Can You Be of Normal Weight and Still Be Obese?

What Is a Healthy Weight Anyway?

Body Weight Misperceptions: Not All Obese People Think They Weigh Too Much

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