ShFit Talk #23 - BMI & Body Fat Percentage


So often when you decide to kick off your Fitness Journey, your GP, or Personal Trainer will often provide you with some starter info including your BMI and Body Fat percentage.


Your BMI number is a great starting point when it comes to understanding what a healthy weight would be for you but it is not the only deciding factor.


Usually BMI values that fall between 18.5 and 24.9 are considered normal. When the number falls between 25 and 30 one is considered overweight, and then when the number is greater than 30 one is considered obese. There are a number of health risks associated with BMIs that are more than 30 including heart disease, diabetes, high blood pressure, even stroke and some cancers.


Just as a BMI over 30 can lead to health issues, a BMI UNDER 18.5 is also considered unhealthy and can be an indicator of malnutrition or an eating disorder. Being underweight can also compromise the function of the immune system and lead to respiratory and digestive diseases, cancer, osteoporosis and more.


So clearly BMI can be an indicator but it does not provide the end all be all of a person's health risks. BMI does not take into account a number of factors such as bone or muscle mass. According to some research, more than half of Americans have a normal BMI but a high body fat percentage, this is known as normal weight obesity. A person who has normal weight obesity is just as unhealthy as someone with a high BMI. Researchers are currently working to determine what percentage of body fat counts as obesity when your weight is normal, and whether guidelines should be different depending on things like your age and sex.


Just as you can have a normal weight and still be “obese”, it can go both ways, for example, many of us live an active lifestyle. We make sure to get our cardio in and spend time at the gym lifting weights and doing resistance training, because of this you may actually have a healthy body fat percentage, but your BMI may be in the “obese” range. BMI is a tricky little thing.


Race can also play a role when only using BMI to determine health risks, for example people with Asian descent, like my significant other, actually have an increased risk of health problems at a LOWER BMI than other races. South Asians, in particular, have especially high levels of body fat and are more prone to developing abdominal obesity, which may account for their very high risk of type 2 diabetes and cardiovascular disease.


In 2004, WHO reviewed the evidence regarding Asians' higher risk of weight-related diseases at lower BMIs but declined to change the overall standards for Asians claiming more research needed to be done. However since then and with new research changes are happening, China and Japan for example have re-define overweight as a BMI of 24 (instead of 25) or higher and obesity a BMI of 28 or higher (instead of the WHO standard of 30). India has re-defined overweight as 23 or higher, and obesity as 27 or higher.


So I keep mentioning Body Fat. Body Fat is becoming a way of providing a better picture of a person's risk to weight related diseases then BMI. Body Fat Percentage actually distinguishes the Fat from the Muscles and calculates how much FAT is in the body providing a more accurate number. When we take a highly trained athlete or lets say a UFC fighter and compare the BMI and Body Fat, we might find the athlete is overweight according to BMI but actually healthy and not overweight when calculating BodyFat.


According to the American Council on Exercises


Women

  • Essential Fat: 0-12 percent

  • Athletes: 14-20 percent

  • Fitness: 21-24 percent

  • Acceptable: 25-31 percent

  • Obese: 32 percent+

Men

  • Essential Fat: 2-4 percent

  • Athletes: 6-13 percent

  • Fitness: 14-17 percent

  • Acceptable: 18-25 percent

  • Obese: 26 percent+


Essential Fat is what you think it is, essential stuff. It is the fat in the marrow of bones, in the heart, lungs, liver, spleen, kidneys, intestines, muscles, and lipid-rich tissues all throughout the central nervous system. Essential fat are necessary for normal bodily functioning.


The rest of the fat that we don’t need, but for some reason seems to be there, is called non-essential fat. This extra or excess fat is used for storage, insulation and to protect vital organs. Non-essential fat might be stored around organs known as visceral fat or it might be stored throughout the body underneath the skin known as subcutaneous fat. The more of the non-essential fat we have the higher our Body Fat Percentage.


So how do you calculate Body Fat Percentage? To get the best results it is suggested you weigh yourself first thing in the morning, before you even eat or drink. Then take a waist circumference measurement around the largest part of your belly, usually that is the belly button. Be sure not to suck in or hold your breath when measuring. Men are simple, just waist and you're good. Women…..a little harder. Women have the pleasure of also Measuring the smallest part of the wrist, largest part of the hips (usually where that butt be poppen out) and the widest part of your arm below your elbow. Lucky Ladies. Sigh.


After you get allllllllll those numbers, you can plug them into a body fat calculator. Active.com has a good one. https://www.active.com/fitness/calculators/bodyfat


So I know that Body Fat Percentage sounds like the Winner right, compared to BMI but Body Fat Percentage as with everything has its downsides. Determining a person’s body fat percentage are not all equal, and the most accurate methods are not readily available to everyone. The two most common methods that you see at the gym or people using at home are the skin fold measurement and bioelectrical impedance analysis.


The skin fold measurement involves using a device called a caliper to lightly pinch the skin and underlying fat in several places. This quick and simple method of estimating body fat requires a high level of skill to get accurate results. The bioelectrical impedance analysis is very common in the gyms, we used to use them at my old job. BIA uses a weak electric current that flows through the body and the voltage is measured in order to calculate the resistance of the body.


The accuracy of each of these vary and the error rates can be as high as % percent in some cases! 8% that can put you from acceptable to obese real quick. Other more accurate methods, such as X-ray analysis and water displacement, are much more complicated and not as readily available.


The one thing that is clear is that if we do have a high body fat, we want to reduce it. The most basic solution is: burn more calories than you eat - your body will burn the fat. That sounds super easy but it is not just that, it is a lifestyle change/adjustment. You have to take your diet into consideration while incorporating cardio and resistance training into your life.


It is important to remember that fat does play an important role in living a healthy lifestyle but it is important to keep those non-essential fats at a healthy level for a long and happy life.


So Lets review.

BMI is a quick and easy way to get a general idea of a personal risk to weight related diseases, If you workout regularly, like we do, we should calculate our body fat percentage periodically to get a more accurate picture of your health and fitness.


Remember it is important to work with your GP if you have concerts or need help in determining if you are at risk of any health related problems. If you want to know what your happy healthy weight should be. If you are pregnant or just struggling with weight loss or weight gain and especially if you are considering any weight loss surgery. Depending on what your needs and goals are your GP can help you….cuz well they did go to college, then medical school, then residency, then get licensed, then worked in the field for years and years and years hell it takes like 11-14 years just to become a doctor in the USA soooo yeah they got the answers for your questions and they are here to help. :-)



BMI Chart



Body Fat Calculator:

https://www.calculator.net/body-fat-calculator.html


https://www.verywellfit.com/how-to-use-body-fat-percentage-calculator-3858855






References:

https://goshenhealth.com/blog-articles/february-2017/bmi-vs-body-fat-which-number-is-more-important#:~:text=Body%20fat%20percentage%20distinguishes%20fat,is%20a%20more%20accurate%20number.


https://diet.mayoclinic.org/diet/eat/what-is-your-bmi?xid=nl_MayoClinicDiet_20160426


https://www.mayoclinic.org/diseases-conditions/obesity/expert-answers/normal-weight-obesity/faq-20058313


https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3726536/


https://www.hsph.harvard.edu/obesity-prevention-source/ethnic-differences-in-bmi-and-disease-risk/



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