A New Estimator of Whole Body Fat Percentage

While DEXA scans (Dual Energy X-ray Absorptiometry) are intended to measure bone mineral density, they also provide an accurate estimate of body fat percentage but not everyone wants to- or is able to go for  this kind of testing to determine how much body fat they have. While most gyms and many pharmacies often have handheld impedance body fat analyzers, these can be affected greatly by changes in body water status, as can high tech digital bathroom scales that have body fat analyzers built in.

Determining Body Fat Percentage based on BMI

Body Mass Index (BMI), which is body mass divided by the square of body height is often used to determine whether someone is normal weight, overweight or obese despite the fact that it is limited in its ability to estimate body fat percentage due to misclassification of body fat-defined obesity. For example, a BMI ≥30 which indicates obesity overlooks nearly 50% of women who have a body fat percentage > 35% which the cutoff for obesity. The US Third National Health and Nutrition Examination Survey estimated the diagnostic accuracy of BMI for body fat-defined obesity at 94% for women and 82% for men [1].

The body fat percentage chart below from the American Council on Exercise (ACE) is a commonly used by trainers and gyms to determine body fat percentage but is limited since it is based on BMI.

ACE body fat percentage chart

Determining Body Fat Percentage Based on Anthropometrics

There are a number of equations based on body measurements (anthropometrics) that have been proposed as alternatives to BMI to better estimate whole body fat percentage. Some require more than 10 different measurements, others require up to 4 different skin-fold measurements using calipers and even others are complex equations using multiple measurements. The common problem amongst all of the existing equations is a lack of simplicity, limiting their use in routine Dietetic or medical practice.

Determining Body Fat Percentage Using Relative Fat Mass (RFM)

A recently published study systematically explored more than 350 anthropometric measurements with the aim of identifying a simple linear equation that is more accurate than BMI at estimating whole body fat percentage in both men and women.

The equation is amazingly simple;

Relative Fat Mass (RFM): 64−(20í—(height/waist))+(12í—sex),where sex = 0 for men and 1 for women.

Click here for an article on how to accurately measure your waist circumference for use in this equation.

Compared with BMI, the Relative Fat Mass (RFM) equation was more accurate for body fat-defined obesity among both men and women over 20 years old and RFM was more accurate than BMI for those with a high body fat percentage and this accuracy held for those that were Mexican-Americans, European Americans and Africans-Americans.

Looking at the equations another way, Relative Fat Mass (RFM) in both metric and American measurements is;

Relative Fat Mass (RFM):

Men: 64 — (20 x height/waist circumference)
Women: 76 — (20 x height/waist circumference)

How to Interpret Relative Fat Mass Results

Based on the research of Gallagher et al and data from the World Health Organization, health body fat ranges have been determined as follows;

Body Fat Ranges for Standard Adults

A 41 year old male with an RFM of 32.2 would be considered at the low end of “obese”.

A 60 year old female with an RFM of 38.9 would be classified at the low end of “overfat”.

A 50 year old female with an RFM of 33.4 would be classified at the higher end of the “healthy” range.

Some Final Thoughts…

Obesity is an significant risk factor for multiple chronic diseases and conditions including Diabetes, coronary artery disease, hypertension (high blood pressure) and certain types of cancer [1].

This new and very simple equation accurately estimates whole body fat percentage enable individuals to easily calculate whether they are have increased weight to lose and will enable clinicians to help their patients achieve optimal weight and waist circumference.

If you want to learn how to eat well and lose weight and inches and achieve a healthy body weight and waist circumference, I can help. I offer a number of services and packages that can be taken in-person in my Coquitlam (British Columbia office) or via Distance Consultation (Skype, long distance telephone). You can click on the Services  to learn more or have a look around the Shop. Please feel free to send me a note using the Contact Me form on the tab above if you have questions and I will reply as soon as possible.

To your good health!

Joy

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Copyright ©2018  The LCHF-Dietitian (a division of BetterByDesign Nutrition Ltd.) 

LEGAL NOTICE: The contents of this blog, including text, images and cited statistics as well as all other material contained here (the ”content”) are for information purposes only.  The content is not intended to be a substitute for professional advice, medical diagnosis and/or treatment and is not suitable for self-administration without the knowledge of your physician and regular monitoring by your physician. Do not disregard medical advice and always consult your physician with any questions you may have regarding a medical condition or before implementing anything  you have read or heard in our content.

References

Woolcott OO, Bergman RN. Relative fat mass (RFM) as a new estimator of whole-body fat percentage ─ a cross-sectional study in American adult individuals, Scientific Reports; Volume 8, Article number: 10980 (2018), https://www.nature.com/articles/s41598-018-29362-1

Gallagher, D. et al. Healthy percentage body fat ranges: an approach for developing guidelines based on body mass index. Am J Clin
Nutr 72, 694—701 (2000).

Importance of Waist Circumference & Waist to Height Ratio

Most of us know that obesity is where a person has high levels of body fat, but at what point does overweight become obese? There are different ways of determining this and one way that many people are familiar with is the Body Mass Index.

Body Mass Index (BMI) classifies whether a person is overweight or obese by looking at their weight to height ratio. It is calculated by taking a person’s weight (in kilograms) and dividing it by their height (in meters squared).

BMI= weight (kg) / height (m) x height (m).

People are considered overweight if their BMI is between 25 and 29.9 and obese if it is above 30.

There are different levels of obesity, too. For Caucasians*:

Class I obesity is a BMI between 30 and 34.9.

Class II obesity is a BMI between 35 and 39.9.

Class III obesity (also called morbid obesity) is a BMI is greater than 40.

*There is a different scale for those of Asian and South Asian ancestry, which is approximately 5% lower.

Research has found that waist-to-height ratio is a much better predictor than Body Mass Index (BMI) of cardiovascular health risk such as heart attack and stroke, as well as a shorter lifespan due to other illnesses. 

A meta-analysis from 2012 pooled data from multiple studies, and examined Waist to Height Ratio (WHTR) in more than 300, 000 adults from several different ethnic groups and found that was a far better predictor of cardiovasular of metabolic risk factors in both men and women, than BMI [1].

A 2014 study found a correlation between Year of Life Lost (YLL) for different values of Waist to Height Ratio (WHtR) and found that YLL increased dramatically in both males and females when above 0.52 – a waist circumference of just over half one’s height [2].

Waist-to-Height Ratio Is More Predictive of Years of Life Lost than Body Mass Index [2]
These two studies found that the least amount of years of life lost is associated with a Waist to Height Ratio of 0.5. That is, our waist circumference should be less than half our height, even if our BMI is in the “normal range”*.

*Both males and female non-smokers have a slightly increased Years of Life Lost at waist circumference > 0.50, even when their BMI was in the normal range (18.5 to to 22) – which means that waist circumference is a more important predictor of shortened lifespan due to cardiovascular disease, than BMI.

Determining Waist to Height Ratio

If you’re a male and 5’10” tall (70″ tall), then to be in the lower risk category, your waist circumference should be 35 inches or less.

If you’re a female and 5’6″ tall (66″ tall), then your waist circumference should be 33 inches or less.

But where should we measure waist circumference?

Is it where we wear our pants? Is it at the smallest part of our belly, where it dips in? Is it where our navel (belly button) is? Each one of these will produce very different results.

Measuring Waist Circumference

For the purposes of calculating risk associated with carrying excess weight around the middle, waist circumference and hip circumference need to be taken at very specific locations, as described below.

Using a flexible seamstress tape measure, stand in front of a mirror so that you can see both the front and back of where you are placing the tape measure.

It is also important that your belly is completely relaxed when taking the measurement, not sucked in.  One way to do that is to taking a deep breath and let it out fully just as the measurement is taken.

Where to measure waist circumference

Take your waist circumference at the midpoint (i.e. half way) between your lowest rib and the top of your hip bone (called the ”iliac crest”) — being sure that the tape measure is perpendicular to the floor (i.e. not higher in the back or the front).

Looking at the graph above, one can see that for every little bit over 0.5, the risk rises steeply.

Where to Measure Hip Circumference?

Hip circumference is also needed for other assessors, including the waist to hip ratio. Measuring hips should be done at the widest part, making sure the tape measure is the same height in the front and the back.

How Much Should I Weigh?

People often ask me “how much should I weigh” – wanting me to provide them with a specific weight in pounds, or kilos. My usual answer is that when your waist circumference is half your height and your lab test results are optimal, everything else is aesthetics (what you look like). While I can provide a ball-park figure based on height and weight, how much people should weigh is better determined by them having the lowest risk of heart attack or stroke (cardiovascular disease) and the lowest amount of Years of Life Lost.

Health is not a number on the scale.  Its the measurement of the amount of fat in our abdomen, around our liver, kidneys, pancreas and heart.

If your waist circumference is greater than 0.5 you are at risk. If you have been diagnosed with type 2 diabetes or pre-diabetes, high blood pressure or high cholesterol, then this risk is compounded.  Add to that a family history of these metabolic diseases, and your risks are even higher.

While we can’t change our family history, we can change our diet and lifestyle and lower our risk.

Attaining a waist to height ratio of 0.5 is often associated with lower blood sugars, lower blood pressure and better cholesterol – even more so when the diet to achieve the weight loss is intentionally designed for these outcomes.

If you would like help getting on your own road to better health, please send me a note using the Contact Me form on this web page, and let me know how I can help.

To our good health,

Joy

You can follow me at:

https://twitter.com/lchfRD

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References

  1. Ashwell M, Gunn P, Gibson S (2012) Waist-to-height ratio is a better screening tool than waist circumference and BMI for adult cardiometabolic risk factors: systematic review and meta-analysis. Obes Rev 13: 275—286
  2. Ashwell M, Mayhew L, Richardson J, Rickayzen B (2014) Waist-to-Height Ratio Is More Predictive of Years of Life Lost than Body Mass Index. PLoS ONE 9(9)

Copyright ©2018  The LCHF-Dietitian (a division of BetterByDesign Nutrition Ltd.)

LEGAL NOTICE: The contents of this blog, including text, images and cited statistics as well as all other material contained here (the ”content”) are for information purposes only.  The content is not intended to be a substitute for professional advice, medical diagnosis and/or treatment and is not suitable for self-administration without the knowledge of your physician and regular monitoring by your physician. Do not disregard medical advice and always consult your physician with any questions you may have regarding a medical condition or before implementing anything  you have read or heard in our content.

What Regulates Body Weight?

Body weight is not under our control as much as we’d like to believe, but is a tightly regulated process that involves a variety hormones with some of the major ones being leptin (a hormone that regulates fat stores by  inhibiting hunger), ghrelin (a hormone that increase hunger when your stomach is empty) and insulin, which plays a very significant role in hunger, eating behavior and fat management. Insulin is one of the major controllers of the body’s “set point”.

What is “set point”?

Think of set point like the thermostat in your house; when the air gets too cold, the thermostat is engaged, and the furnace comes on and when the air gets a little too hot, the thermostat shuts the furnace off. Your body’s set point is maintained by a complex set of hormonal mechanisms that works to maintain your body at its current weight.  If you eat a lot more one day because it’s a special occasion, the next day you won’t feel as hungry as usual, and will eat less. When someone who normally eats a carbohydrate-based diet restricts calories, their body slows its metabolism and lowers the amount of energy (calories) it uses for vital bodily functions in order to ‘save’ the limited calories for use by their brain. In fact, the amount of energy used by your body at rest (called Basal Energy Expenditure) can decrease by as much as 30-50% in order to save those calories!

This saving of calories for essential functions is why when people who are used to eating carbs ‘fast’ or limit the number of calories they eat, they feel cold, tired and find it hard to focus.  This is the body ‘saving’ the few calories for essential body functions, such as for their brain and organs. This doesn’t happen to someone who is fat-adapted, because they use their own fat stores to maintain blood and brain glucose, and for other energy needs.

Equally part of maintaining the body’s set point, when an overweight person takes in too many calories, their body will try to get rid of them by increasing its Basal Energy Expenditure and speeding up breathing rate (respiration), increasing heart rate and generating more body heat.

So, whether we are overweight or underweight, the body will adjust its processes to maintain its set point’.

This is why the so-called calorie in, calorie out model, doesn’t work – because it is not simply a matter of “eating less and moving more“. When people who are carb-dependent restrict their calories, their metabolism slows and so they burn way less calories!

Calories in and calories out are not independent of each other but inter-dependent on each other; when one is lowered (calories in), so is the other (calories out, metabolism).  When one is increased (calories in), so is the other (calories out, respiration, heat generation).

It’s really not as simple as “eating less and moving more” to lose weight, because when we both restrict calories and increase our exercise, our body responds by increasing hungerincreasing craving (especially for foods such as simple carbs that can be broken down quickly for glucose for your blood) and by decreasing the amount of energy it uses. Using the thermostat analogy, our body turns the thermostat down.

Wouldn’t you think that if it were really as simple as “eating less and moving more” that more people would be slim!

Restricting calories doesn’t work for long term weight loss because the body compensates by lowering its energy expenditure. It’s not about how many calories we take in, but about what changes set point’.

It’s mainly about insulin. We have to reduce insulin.

Low-carbohydrate diets and increasing the amount of time between meals (called “intermittent fasting”) are two ways to lower insulin.

Lowering insulin, will in turn will lower blood sugar and when this lifestyle is maintained, over time, it has even shown by researchers to be able to reverse the symptoms of Diabetes. That doesn’t mean people aren’t Diabetic anymore – they are but the symptoms of Diabetes, namely high blood sugar (reflected in high fasting blood glucose and HbA1C) are in remission. Other added benefits include a lowering of blood pressure (which is closely tied to insulin), gradual, sustainable weight loss and a normalizing of triglycerides as well as some cholesterol markers.

When people are ‘fat-adapted’, they have a ready supply of fuel for their bodies (their own fat stores!), and so their metabolism doesn’t slow down when they eat this way. Their bodies continue to burn calories at the usual rate!

Furthermore, they aren’t cold, tired and hungry because they have excess fat stores to serve as a constant supply of fuel for their brain, blood and muscles. Fat is broken down for ketone bodies which can be used for most body processes, and the essential glucose needed by our blood and brain is easily synthesized by the breaking down of fats. 

Want to know more about how I can help you?

Why not send me a note using the Contact Us form above and I will reply shortly.

To our good health!

Joy

You can follow me at:

 https://twitter.com/lchfRD

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Note: Everyone’s results following a LCHF lifestyle will differ as there is no one-size-fits-all approach and everybody’s nutritional needs and health status is different. If you want to adopt this kind of lifestyle, please discuss it with your doctor, first.

Copyright ©2017 The LCHF-Dietitian (a division of BetterByDesign Nutrition Ltd.) 

LEGAL NOTICE: The contents of this blog, including text, images and cited statistics as well as all other material contained here (the ”content”) are for information purposes only.  The content is not intended to be a substitute for professional advice, medical diagnosis and/or treatment and is not suitable for self-administration without the knowledge of your physician and regular monitoring by your physician. Do not disregard medical advice and always consult your physician with any questions you may have regarding a medical condition or before implementing anything  you have read or heard in our content.

The Limitations of Common Ways of Determining Weight Loss

People who are eating differently in an effort to lose weight often hop on the scale daily to see how they’re doing. What they fail to consider is that an average adult’s body weight can fluctuate by as much as 4  1/2 pounds per day — solely as a result of changes in the amount of water they are retaining or excreting.

The Limitations of Using a Scale to Determine Fat Loss

An 80 kg person has, on average 48 liters of water in their body. The problem with using body weight as an assessor of fat loss is that the human body does not precisely regulate body water content.

Above 49 liters of water, the kidneys of an 80 kg person will clear the excess water by causing the person to urinate more and below 47 liters of water, the 80 kg person will feel thirsty and increase their fluid intake. People’s “weight” is affected by this change in body water content of ~2 liters per day — which weighs approximately 2 kg or 4.4 pounds! Put another way, each day our “weight” can fluctuate by this amount solely due to the difference in retained or excreted water.

Since there is no way to measure this daily change in water weight in non-clinical settings, the standard scale is a very imprecise way to measure fat loss over the short-term.

Waist Circumference

Many people know that carrying excess weight around the middle increases one’s risk of cardiovascular disease, including heart attack so they measure their waist circumference frequently. Even if waist circumference is measured halfway between the lower rib and the top of the hip bone, with a fully relaxed abdomen, their are limitations to using this as a short term measure of weight loss.

The Limitations of Using a Tape Measure to Determine Fat Loss

Since the average person’s body weight fluctuates by as much as ~4 1/2 pounds per day due only to changes in body water, a tape measure fails to capture decreases in waist circumference stemming from the kidneys excreting water.

That said, waist circumference is helpful as a long-term indicator of weight loss, just not a short-term one.

Body Fat Percent

Some people have bathroom scales that have body fat analyzers built in and think that what it is measuring is the amount of fat they are carrying, however a number of factors can influence this reading.

The Limitations of Using a Body Fat Analyzer to Determine Fat Loss

Body Fat Analyzers use electrical impedance to determine fat percentage, and this measurement is affected by a number of conditions, including environmental (room) temperature, a person’s hydration status, as well as emotional stress. Since hydration status can fluctuate by ~4 pounds per day, a body fat analyzer is no more accurate as a short-term measure than a standard bathroom scale, without it.

How to assess short-term weight loss

How one’s own clothes fit and comparative ‘before’ and ‘after’ photos are a much better short-term assessor of fat loss than a scale, a tape measure and a body fat analyzer. Since body water fluctuates considerably on a low carb high fat diet due to changes in sodium levels, I recommend that people eating a low carb high fat diet weigh themselves once every two weeks on the same day of the week, at the same time of day and measure their waist circumference at the same time. If they have a scale that assesses body fat percent once every two weeks is sufficient for taking these measurements.

None of these will provide much information on actual fat loss over the short term…so why rely on them for that, but they will be helpful measurement over the longer term.

Sodium and Body Water Content

As mentioned in a previous article, by eating only when hungry and only until no longer hungry, insulin levels have the opportunity to fall to baseline – something they do naturally after not eating for 12 hours.

On days where the time until eating is extended by a few hours (i.e. “intermittent fasting”), insulin levels stay low for an even longer period of time.  In response, our kidneys excrete sodium in a process called naturesis.

Failing to supplement sodium while eating low-carb high fat can result in intense headaches – and if sodium remains low, potassium will also be excreted to keep the necessary sodium-potassium balance. This drop in potassium often results in irregular heart beats, known as arrhythmia.

Phinney and Volek (The Art and Science of Low Carbohydrate Living) recommend that if one is eating less than 60 gms of carbs per day, that 2-3 grams of sodium should be added to the diet (provided the person is not taking any diuretics or other blood pressure medication).

A half a teaspoon of table salt or sea salt provides 1000 mg or 1 gram of sodium.

Final Thoughts

Since hopping on the scale daily or even several times a week won’t provide any useful information, nor will measuring our waist circumference or using a body fat analyzer too often – why do it? Part of ‘getting healthy’ ought to include having a healthy body self image – something that won’t be nurtured by obsessing about such “numbers”.

Short-term measures of success

Short-term success is best measured visually – with comparative photos taken from the same distance away, from the same relative height and wearing the same clothing.

How one’s clothes are fitting is another way.

A person who is insulin resistant or Type 2 Diabetic should be seeing both their fasting blood glucose and post-prandial (2 hours after a meal) glucose levels gradually coming down. If they aren’t then they should schedule an appointment with their Dietitian to find out why that is.

Medium-term measures of success

Medium-term measures of success in eating low carb high fat can be measured both subjectively and objectively. Subjective measures include weighing oneself and taking one’s own waist circumference once every two weeks. Objective measures include having your Dietitian weigh you on a clinical scale, having her assess your waist circumference and body fat percentage using both a device that measures electrical impedance, as well as using good old-fashioned calipers, that measure subcutaneous (under the skin) fat, in 3 or four specific locations on the body.

A person with high blood pressure should be seeing both systolic (the first number) and diastolic (the second number) blood pressure coming down and Type 2 Diabetics or those with insulin resistance should be continuing to observe lower fasting blood glucose and post-prandial (2 hours after a meal) glucose levels.

Longer-term measures of success

After 6 or 8 months eating low carb high fat, both subjective and objective measures should be continuing to lower in a reasonably linear fashion. Of course there will be times where a ‘plateau’ is reached, but if that lasts more than two or three weeks, then its important to check in with your Dietitian to make sure the amount of carbs you think you are eating is what your Dietitian has been determined as being best for you.

A Type 2 Diabetic should be seeing both their fasting blood glucose and post-prandial (2 hours after a meal) glucose levels approaching more normal levels and both Type 2 Diabetics and those with insulin resistance (“pre-diabetes”) should have their HbA1C assessed at a lab every three months, as this provides insights into one’s 3-month average blood glucose level. Fasting blood glucose provides a ‘snap-shot’ of blood sugar in the morning after not eating, and should be done twice a year by a lab, especially if one is Diabetic. Comparing lab test results to previous lab test results is an objective indicator of the effect that eating low-carb high fat is having on specific markers and provides an opportunity to determine if the amount of carbs being eaten may still be too high.

The most accurate assessor is a 2 hour glucose tolerance test, however few doctors will requisition this after one is diagnosed as Type 2 Diabetic.

Finally, every year or so, it is helpful for those who have been diagnosed as Diabetic to have their fasting insulin, C-Protein and AM Cortisol levels assessed and compared to previous results. For these, your doctor may refer you to an Endocrinologist.

Remember, achieving health is a journey and takes time and like most journeys, it is best not done alone.

Have questions about how I can help or about the services I provide?

Please send me a note using the form on the “Contact Us” tab, above.

To your good health!

Joy

Note: Everyone’s results following a LCHF lifestyle will differ as there is no one-size-fits-all approach and everybody’s nutritional needs and health status is different. If you want to adopt this kind of lifestyle, please discuss it with your doctor, first.

Copyright ©2017 The LCHF-Dietitian (a division of BetterByDesign Nutrition Ltd.) 

LEGAL NOTICE: The contents of this blog, including text, images and cited statistics as well as all other material contained here (the ”content”) are for information purposes only.  The content is not intended to be a substitute for professional advice, medical diagnosis and/or treatment and is not suitable for self-administration without the knowledge of your physician and regular monitoring by your physician. Do not disregard medical advice and always consult your physician with any questions you may have regarding a medical condition or before implementing anything  you have read or heard in our content.


follow me at:
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