My company hosted a health fair on Monday. Various different insurance companies, eye doctors, dental providers, etc. came to one of our offices to tell us about how great their services are. I'm sure they're all great, but that's not why I'm telling you about this health fair. I'm sharing this not-so-juicy tidbit because of the comparison of Body Mass Index (BMI) against body fat percentage. BMI is calculated based on your height and weight. Your body fact percentage can be measured with the use of a Bioelectrical Impedance Analysis (BIA) - something like this. The long and short of it is that an electrical current is sent through your body via two conductors. The resistance of this circuit provides an indication of the amount of fat between the conductors. Fat is a poor conductor of electricity, whereas muscle is a good conductor due to the water and electrolytes found in the muscles. Okay, so you've got some of the theory now. And if you've used one of the hand-held or scale BIA monitors, you've seen your % body fat. What does this mean? Well, there's different standards, but here's the breakdown I received at the health fair.
Though I don't really want to share this value, I will... just to make a point. My percent body fat was 30.7%, which is within the healthy range. However, my BMI is 29.2, which is on the overweight/leaning toward obese side.
My conversation with the woman who gave me the BIA test went a bit like this:
Health Professional: Oh, 30.7% - that's good. You're healthy. Oh, but your BMI is 29.2, that's right at the edge of the critical range. You really need to watch that. You should make sure you're staying active.
Me: Well, I exercise 30-90 minutes almost every day, and I watch my food intake and follow clean eating guidelines. What else should I be doing?
Health Professional: Oh, um, just keep doing what you're doing. Once you hit 30 years old, your metabolism starts to decrease.
Me: Oh, thanks. So I'm great as I am, even though you told me I'm almost obese? (Okay. So, I didn't actually say that, but I thought it. There were probably some mean names thrown in there, too.)
Seriously though... I'd really like to know how I'm considered healthy with one standard, yet border-line obese with another. I feel healthy. I can handle 90 minutes of moderate to intense exercise on a fairly regular basis, and I seem to be able to move around just fine, minus some joint pain. Hey. I'm not perfect. I still have weight I think I should lose to reduce said joint pain. So I'm going with the decision that BMI is BS!
Still not convinced? I decided to play around with the numbers to see how the healthy range of each scale measured up to each other (at least for my fat-free body mass). The table below is what I calculated for my body. I've highlighted the cells in green that fall within the "healthy" range for each method.
Body fat percentage and BMI are completely exclusive of each other for me. To be considered healthy according to my BMI, I'd need to become a professional athlete... or completely starve myself, like seriously stop eating period, maybe throw in a daily laxative for good measure, and stop moving altogether. I obviously can't keep working or strengthening my muscles, because I would need to lose muscle mass to get to the low end of the BMI scale. I should also point out that essential fat for women is 10-13% (for men it's 2-5%), so if you take that into consideration, my 10-13% body fat range corresponds to 22.5-23.3 BMI. This leaves me with the BMI range of 23.4 to 24.9, that could maybe be achievable without completely disregarding the % body fat... that is if I were an athlete.
Anyways, I get really up-in-arms about this because I've had doctors fret about my BMI and tell me that I should aim for a weight that is unattainable for my body type/composition. I had a doctor in the past tell me that I could stop losing weight once I hit a weight that corresponded to roughly a BMI of 20. Hello 0% body fat, good-bye curves, but more importantly, good-bye health, energy, and exercise. I feel very grateful that my dad is an exercise physiologist and physical activity epidemiologist. Who knows how different I would have been if I blindly attempted such ridiculous weight-loss goals. I'd probably be constantly depressed and food-obsessed. I'd be constantly thinking about food and how hungry I am because I'd be practically starving myself, yet I'd be depressed because I would never be able to reach these goals.
In summary... I'm choosing to ignore BMI from here on out. Instead I will listen to my body and use my eyes to assess how I think I look. I may supplement this with sporadic body fat percentage measurements if I feel like it. BMI is BS! Thanks for listening.
Note: Please remember that the numbers I provided here apply to me and my body. If you're truly serious about weight loss and your percent body fat, I suggest talking to a health professional and/or a nutritionist. While the BIAs that you can buy on Amazon or at fitness stores can give you an estimate of your body fat, it is not the most accurate method of measurement out there. For example, underwater weighing (hydrostatic weighing) measures the displacement of water volume when your body is submerged in water and measures the change in weight. This method is more accurate than the hand-held monitor. Just so you know...
