“To fail to plan is to plan to fail.” -Benjamin Franklin

Some of you may have heard of SMART goal setting.

For those of you who haven’t, SMART is an acronym for specific, measurable, achievable, realistic, and timely. The idea, in a nutshell, is that all goals should be SMART if they are going to be of any use at all. There is no point setting a goal that lacks even one of these five components. In this post, I’m going to discuss how to calculate body fat percentage and how that relates to the “measurable” component.

First, let me say a few things about the “specific” component.

A fitness goal should be specific in order for it to be measurable. If your goal is to “lose weight”, that’s pretty much impossible to measure. My main fitness goal for 2010 was to drop my body fat percentage below 8% within 6 months and keep it there for the remainder of the year. Notice that I used body fat percentage, not weight, as my preferred unit of measurement. I believe body fat percentage is a superior indicator of overall body composition to weight. Someone can be very muscular and at a very low body fat percentage and still be considered “overweight” strictly on BMI, even though they look amazing. Conversely, an individual can be “skinny fat” with a reasonable weight, but very high body fat percentage that shows when they take their shirt off.

I strongly recommend using body fat percentage as your measure of body composition.

If your body fat percentage is on point, the weight will take care of itself. The drawback to using body fat percentage is that it is not the easiest thing to measure. To get a truly accurate measurement of body fat percentage, you need advanced procedures such as an MRI (magnetic resonance imaging) or DEXA (dual energy x-ray absorptiometry) which are expensive. I measure my body fat percentage weekly and I don’t know about you, but I’m not willing to shell out $50 – $100 per week to measure my body fat percentage.

What do I use?

I use an electronic body composition scale which measures body fat percentage through bioelectrical impedance analysis (BIA). BIA sends a small electric current through your body to gauge total body water which it uses to estimate body fat percentage. Don’t worry, it’s perfectly safe. The drawback: it’s not very accurate. BIA scales tend to understate body fat percentage. Still, I’m okay with this because I’m more interested in the trend over time than the actual number.

The trick is to keep as many variables constant as possible.

I try to weigh myself on the same day every week. This doesn’t always happen, but I do always weigh myself at approximately the same time of day (in the evening) after working out, showering, and urinating but before eating or drinking anything. When you are tracking measurements over time, it is very important to control these variables when using a BIA scale because it relies on total body water to measure body fat percentage. If I were to chug a couple of glasses of water and then weigh myself again, my body fat reading my jump up by 1% or so.

Again, I’m okay with this because I’m not a professional athlete or bodybuilder who needs to know an exact number. I really want to just make sure I’m in the right ballpark (definitely in the single digits, around 8% +/- 1-2%). The advantage of using a BIA scale is that it’s very inexpensive. This was a one-time cost of about $60. I bought mine a few years back and technology has improved since then, so today you can probably get a cheaper, more accurate one.

Now for the fun part: tracking your progress.

As I mentioned, I generally weigh myself once a week… actually, let’s say once every 5-9 days. If my control variables aren’t right for a weigh in (for example, if I forget to weigh myself before eating dinner), then I’ll wait until the next day. I’ve been doing this for over a year now and tracking my numbers in an Excel chart. I can’t stress how crucial it is to have some kind of visual reinforcement of your progress. For me, an Excel chart is the easiest way to do this. Below are my Excel charts for body fat percentage and weight. As I said, my focus was on body fat percentage. I didn’t really care much about weight. It was just something interesting to track and see how it changed over time as my body fat percentage changed. Notice a pattern?

I started tracking my body fat percentage and weight in September 2009 (the beginning of my “fitness journey”) and I don’t plan to stop… ever.

The constant visual display is perhaps the most powerful tool you can leverage. The reason for this is that it increases awareness and this is critical to achieving your goal and then staying on track. There is an unconscious connection with tracking your progress that gives you something concrete that’s always in the back of your mind. Trust me, it really works. Every time I calculate body fat percentage and look at my spreadsheet, I’m reminded not to let myself go because I don’t want my chart to get out of whack! So, I’m happy to say that I accomplished my body fat goal in 2010. In my next post, I’m going to talk about my new fitness goal for 2011.