BMI: Am I Normal?
Most of you are probably more familiar with BMI, which stands for Body Mass Index. This number is a reflection of two primary factors, height and weight. The scale for results is: Below 18.5 is underweight; 18.5-24.9 is normal; 25.0-29.9 is overweight; and 30.0 or more is obese. Here's another interesting fact for you...being underweight increases morbidity equal to being overweight and/or obese! So, being super model thin can actual be a major risk factor for your health and total life expectancy. Super skinny is super old school. Being in the "normal" range is the best indication for good overall health. What BMI tells you in laymen terms is whether you are at risk for heart disease or diabetes. Research shows a correlation between BMI and these factors specifically. It is a snapshot of your overall "health". Now you may be asking, "When should I use BMI?". Great question! BMI is a great tool and starting point when you are first getting starting with a training program. The flaw with BMI is that as you continue to progress in your training, it becomes less relevant to you. This is where body fat percentage takes center stage.
Body Fat %: The REAL skinny
Being "normal" according to your BMI is one thing, but being lean and mean and ready for the rest of your long, long, life is another. More studies are confirming the importance of body fat percentage as a more accurate assessment of overall health. This is especially true for athletes and those that are continuing to replace fat with lean muscle. Why is muscle described as lean? Well, mostly because when you build muscle and replace fat, you decrease space in your body by roughly 18%! A pound of muscle weighs the same as a pound of fat, but takes up WAY less space. So for those of you seeing inches come off instead of pounds, that is why...and it is a VERY good thing. That is why most trainers will tell you not to be "scale happy" during the first 12-16 weeks of a training program. They will ask you how your clothes are fitting, how well you are sleeping and if your energy levels are effected. All of these are benefits of focusing on inches lost rather than weight lost. It is not uncommon for a muscular person to have a high reading for BMI, yet to be considered lean when looking at body fat percentage. It is also not uncommon to have a normal BMI, but high body fat percentage. Two women could be the same height and weight, making their BMI's equal. One, however could be significantly leaner, having more muscle and less fat, making her the healthier of the two. This is referred to as "skinny fat". The person who weighs the same, but carries more fat is still at risk!
The scale for body fat percentage is women: 10-12% is essential fat; 14-20% is athlete category; 21-24% is fit; 25-31 is acceptable; and 32% or more is obese. For men: 2-4% is essential fat; 6-13% is athlete category; 14-25% is acceptable; and 25% or more is obese. Essential fat is the fat your body needs to run properly. You will also notice that women are, and should be, heavier than their male counterparts. What it measures is the actual amount of fat in the body. Remember, you can be skinny, and still be fat.
Which one should I use?
If you are just starting out and are within 3-6 months of starting a new program, use BMI. Beyond this as training progresses, you should turn to body fat percentage. Both are useful as risk indicators and have a place throughout your training.
Keep pushing yourselves! And don't be skinny fat...be simply PHAT, fly, rock'n, lean, mean....you get the point.
Love,
Lydia
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